Post by fredashbolt on Dynamically Update JSON Payload ^{CODESYS Forge talk (Post)}
I am trying to generate a JSON payload populated with a value that updates for use with a telemetry system, the payload is to be published by MQTT. I have established the MQTT client and can publish a working JSON payload but I can't get the payload to update as the value (iValue) changes. I am using a timer to trigger the .SetValue function periodically, but the JSON will only give the value as it is when it is first initialized using xFirst IF statement. Any suggestions? Thanks VAR pJsonData : POINTER TO JSON.JSONData := factory.Create(); fb_JBuilder : JSON.JSONBuilder; diRootIndex, diObject1Index : DINT; iValue : INT := 10 ; jsonArrayWriter : JSON.JSONByteArrayWriter; wsJsonData : WSTRING(1000); xFirst : BOOL := TRUE; utf8JsonData : STRING(2000); diTempVal : DINT ; PublishTimer : TON ; END_VAR IF xFirst = TRUE THEN fb_JBuilder ( pJsonData := pJsonData , diRootObj => diRootIndex ) ; diObject1Index := fb_Jbuilder.SetKeyWithObject ( "Device" , diParentIndex := diRootIndex ) ; diTempVal := fb_Jbuilder.SetKeyWithValue ( "Temp" , iValue , diParentIndex := diObject1Index ) ; xFirst := FALSE ; END_IF PublishTimer ( IN := PublishTimer.Q = 0 , PT := T#5S ) ; IF PublishTimer.Q THEN fb_JBuilder.SetValue ( iValue , diTempVal ) ; END_IF jsonArrayWriter( xExecute := PublishTimer.Q , pwData := ADR(wsJsonData), udiSize := SIZEOF(wsJsonData), jsonData := pJsonData^, xAsyncMode := FALSE ) ; JSON.Stu.ConvertUTF16toUTF8( ADR ( wsJsonData ) , ADR ( utf8JsonData ) , SIZEOF ( utf8JsonData ) , bStrictConversion := TRUE ) ;
Last updated: 2026-03-10

Post by nickpoon on SysProcessCreate stopped working after SP21? ^{CODESYS Forge talk (Post)}
I'm going through the process of updating the CODESYS Project a machine to 3.5 SP21 (old version was 3.5 SP20). One function that stopped working when upgrading was SysProcessCreate. I need to run a .exe file that is located in C:\Program Files\MQTTStream. Some initial searching suggested that there are new security rules that prevent the SoftPLC from reading/writing files to outside of its Device folder (located here - C:\Windows\System32\config\systemprofile\AppData\Roaming\CODESYS\CODESYSControlWinV3x64\24FD6770) Relocating files helped fix my JSON file reader/writer functions (which were failing previously), but not the case for SysProcessCreate. I've even attempted to just run window's cmd.exe and with: pszCommandLine = 'cd /d C:\Windows\System32\config\systemprofile\AppData\Roaming\CODESYS\CODESYSControlWinV3x64\24FD6770\PlcLogic\MQTTStream & sift-proxy.exe --grpc_uri="https://grpc-api.siftstack.com" --api_key="xxxxxxxxxxxxxxxxxxx" mqtt-client --broker_ip=10.0.10.101 --broker_port=1883 --config_file="mqtt_telemetry_config.json" --username Plantd --password 1234 --stream_metrics --storage_path="sift-proxy-logs"' I have not been able to find a lot of documentation on this, and I suspect the new update may have created a bug for SysProcessCreate. Any help would be greatly appreciated
Last updated: 2026-02-02

Post by konstantin on CAM Motion Recover after STO ^{CODESYS Forge talk (Post)}
Hello Mr. Seidel, both the master and the slave axis are modulo. Basically the situation is as follows: One master cycle is 100 units. Slave's modulo length is 2000 units. In the CAM table I defined 10 master cycles on X axis - 1000 units and on the Y axis is the slave - 2000 units. Then depending on the master position 0 to 1000 units the slave's position is plotted on the Y axis - 0 to 2000 units. For example, while the master is executing the 3rd cycle i.e. above 200 units, I trigger the STO function of the slave and it stops. The master executed his cycle but the slave was stopped during the execution. How can I set the slave to continue the CAM sequence from the point where it stopped i.e. third cycle of the master? When I reset the slave error and sync again, everyrhing starts from master's 0 position. Best Regards Konstantin Kolev
Last updated: 2026-02-13

Post by charleskirkland on Connect to Azure IoT Hub ^{CODESYS Forge talk (Post)}
It sounds like your TLS setup is basically correct, since the handshake works via OpenSSL, so the issue is likely on the CODESYS side rather than the certificates themselves. From what I’ve seen with the Azure IoT Hub Client SL library, you should double-check that the SAS token is actually being generated and passed correctly to the function blocks (especially wsDeviceSaS) and that the MQTT/HTTPS FB is really triggered cyclically-otherwise the controller won’t initiate the connection at all. Also, make sure DNS, time (NTP), and full certificate chain trust are properly configured on the controller, since IoT Hub authentication depends on them even when using SAS tokens. Another thing worth checking is the library/runtime version-there are reports that certain versions changed behavior and caused connection issues. I’d recommend starting with the official demo project (AzureMQTTDemo) and comparing it step by step with your setup to see what’s missing or not triggered. Speed Stars
Last updated: 2026-04-27

Post by timvh on USB Game Controller with Raspberry Pi ^{CODESYS Forge talk (Post)}
I'm not sure it will work, but you could try it with the CmpCharDevice library. You could create a function block that looks something like this: As input for the filename, you have to use your Linux device, e.g.: '/dev/input/event0' '/dev/input/by-path/platform-button@23-event' Off course you must also pass the pointer to the memory where the data can be written to and the size (count in number of bytes) of the buffer. FUNCTION_BLOCK FB_CharDevice VAR_INPUT szFilename: STRING; pbyBuffer : POINTER TO BYTE; udCount : UDINT; END_VAR VAR_OUTPUT iState : INT := 0; nrBytesRead : DINT; END_VAR VAR xInit : BOOL := TRUE; dFlags: DINT := CmpCharDevice.ACCESS_MODE.O_RDONLY + DINT#4000; // see details for flags: http://linux.die.net/man/2/open, + DINT#4000 is for non-blocking hDevice: CmpCharDevice.CmpCharDevice_Implementation.RTS_IEC_HANDLE := -1; Result : CmpCharDevice.CmpCharDevice_Implementation.RTS_IEC_RESULT; END_VAR IF xInit THEN hDevice := CmpCharDevice.CDOpen(szFilename, dFlags ,Result); // if it would not succeed, the result is -1 (Invalid handle) IF hDevice <> 16#FFFFFFFF AND Result = 0 THEN iState := 5; END_IF xInit := FALSE; END_IF IF iState = 5 THEN nrBytesRead := CmpCharDevice.CDRead(hDevice, pbyBuffer, udCount, Result); ELSE nrBytesRead := 0; END_IF Make sure you close the connection properly, maybe by overwriting the default FB_Exit method of the FB: // Clean up device IF hDevice <> 16#FFFFFFFF THEN __TRY CmpCharDevice.CDClose(hDevice,Result); __CATCH ; __ENDTRY iState := 0; END_IF
Last updated: 2026-05-01

Post by timo on String nach erlaubten/unerlaubten Zeichen durchsuchen ^{CODESYS Forge talk (Post)}
Hallo, Ich bastele gerade an einer möglichst einfachen Möglichkeit mit der ich prüfen kann ob ein String Sonderzeichen enthält. Mein Ansatz ist ein ST FB mit einer Case Schrittkette. Ich vergleiche jedes Zeichen des Strings mit allen Zeichen eines vorher definierten Strings erlaubter Zeichen, der A-Z, a-z und 0-9 enthält und ggf angepasst werden kann, wenn ich weitere Zeichen erlaube. Leider wird meine j Zählervariable nicht richtig ausgeführt. Hat da jemand eine Idee? Oder gibt es eine einfachere Lösung/einen fertigen FB den ich mir anschauen kann? FUNCTION_BLOCK Sonderzeichen_Check VAR_INPUT inputString : STRING; // Zu prüfender String startCheck : BOOL; // Startsignal END_VAR VAR_OUTPUT ok : BOOL; // TRUE, wenn keine ungültigen Zeichen END_VAR VAR i : INT := 1; // Input-String Zähler j : INT := 1; // erlaubte Zeichen Zähler allowedChars: STRING := 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'; // Erlaubte Zeichen currentChar : STRING[1]; // Aktuelles Zeichen step : INT := 0; // Schritt END_VAR CASE step OF 0: // Warten auf Start IF startCheck THEN step := 10; END_IF 10: // Initialisierungen i := 1; j := 1; ok := TRUE; // Standard: ok step := 20; 20: // Durchgehen des Eingangs-Strings IF i <= LEN(inputString) THEN currentChar := MID(inputString, i, 1); // Aktuelles Zeichen step := 30; ELSE step := 70; // Alle Zeichen ok END_IF 30: // Durchgehen der erlaubten Zeichen IF j <= LEN(allowedChars) THEN step := 40; // Zu Schritt 40 ELSE step := 60; // Ungültiges Zeichen END_IF 40: // Vergleich IF currentChar = MID(allowedChars, j, 1) THEN i := i + 1; // Nächstes Zeichen im Input step := 20; ELSE j := j + 1; // Nächstes erlaubtes Zeichen step := 30; END_IF 60: // Ungültiges Zeichen ok := FALSE; // Setze auf FALSE step := 0; 70: // Alle Zeichen ok step := 0; END_CASE
Last updated: 2025-01-20

Post by tcarlbom on Read tag values using external program ^{CODESYS Forge talk (Post)}
This is my first time posting in this forum and I am new to codesys. I am a fullstack developer and I am trying to figure out how the following. What would be the best approach to create a own/custom tag browser? Either directly in codesys ide or using a separate custom program (perhaps a winforms application). 1.a. Shall I parse the .project xml file to get a list of all tags in the project? 1b. Shall I use python scripting in codesys ide to get a list of tags? Once one have selected some tags. These tags shall be exposed to a python program which will be acting as a edge computer. It’s fine to be able to import a file. 2a. I found a library called codesys plchandler which (as I understand) acts a rest api server. Is this correct? If so, can I query the api from a custom python script, ie can query what tags exist in project and or read tag values? My research so far. From earlier projects I know that using opc ua would be perfect for this but from my opinion it’s bloating the plc since it’s resource intensive. So opc ua is not an option. Codesys automation server is neat. But I don’t want to rely on some cloud services and subscription based pricing. There seem to be several interesting codesys libraries like mqtt, tcp server and NVL sender which would help me expose plc tags. But all have a common problem. One have to manually write what tags which will be used in these function blocks. I want a similar experience like “selecting” tags in the opc ua or the codesys tracing, ie a tag browser.
Last updated: 2024-06-28

Post by youness on No source code available (cip object) ^{CODESYS Forge talk (Post)}
Hi yotaro, hope your problem was resolved. I had the same, but with an other library title. This exception is not detected during compilation, but rather at a given position in the program (when switching to a given visualization). Although the exception is generated at this point, it does not involve the visualization in question. This error is due to one of 3 reasons: 1) A division by zero somewhere: The program is able to detect divisions by zero at compile time. But in the case of a variable, which takes a valid value at init and changes to 0 at a later stage. 2) An invalid pointer: (either because it has a value of 0, or because it points outside the memory reserved for the program) is being dereferenced. Locate any pointers or interfaces you have in the code and check them - you should also be wary of mixing inline modifications and pointers. 3) Array overflow: Generally when a processing operation is executed outside the array's definition range. Example: a write loop with n iterations is executed on an array of dimmension n-1. On the other hand, the error message may not appear. In the latter case, the error may have fatal consequences, as the overflow has induced writing to potentially forbidden memory areas. This problem can be explained by the fact that it's not always the adjacent memory areas of PLC_PRG that are overwritten, but the memory areas that are randomly allocated to the array during compilation. In this case, however, there is no entry in the log, so you need to integrate the "Implicit Check function", which checks the line of code generating the error. To integrate this functions, click on Application --> POU for implicit controls Regards,
Last updated: 2024-07-16

Post by maldus512 on How to adapt Codesys Control SL to custom board ^{CODESYS Forge talk (Post)}
Hello everyone, I have been given the task to develop I/O drivers for a custom made, Linux based board to allow for Codesys applications to run and control the hardware. I have successfully installed Codesys Control SL for ARM/Linux and tested it with a simple demo application. Now I should start interfacing the runtime to the actual hardware; I should be able to interact with 2 RS485 serial ports, a few GPIOs and an I2C port, all of which already have the corresponding /dev/ interface in the Linux system. I am having trouble understanding how it should be approached. I have found sporadic references that fail to lead to a really comprehensive documentation. For example: The store page (https://store.codesys.com/en/codesys-control-for-linux-arm-sl-1.html#options) mentions a "runtime package" that should allow "Integration of existing C code" and "Usage of local I/Os", which seems exactly what I need to interact with custom peripherals. I have found no further reference to Codesys-C interpop. The Codesys Help page for the runtime package has a page on the "Development of Drivers" (https://content.helpme-codesys.com/en/CODESYS%20Control/rtsllinuxrbpdriverdevelopment.html) that suggests to either "Implement a function block" or "Implement I/O drivers". Those in turn lead to this page (https://forge.codesys.com/drv/io-drivers/doc/Generic/) which describes briefly an XML schema to describe new devices; unfortunately, it doesn't mention what to do with such a description (i.e. how does the runtime know about it) or how it is in any way connected to the actual hardware. Could anyone give me some pointers? I should also mention I have no prior experience with Codesys, so maybe I'm missing an obvious answer.
Last updated: 2024-08-09

Post by fmon on Modbus : dis- / re-connect cable: modbus does not re-start ^{CODESYS Forge talk (Post)}
Hello, I am using codesys Modbus TCP client (4.4.0.0) to communicate with a python modbus server (package pyModbusTCP). I first start my python server on the distant machine. After a fresh codesys compilation, a plc connection/transfer and a PLC run, the modbus connection is OK. Every time in this context the connection is created correctly. When I shut down the server, the modbus connection falls, that is normal. When I restart the python server, impossible to recreate the modbus connexion. With the client autoreconnection, I see on my server that the client tries to connect but unsuccesfully. I have the following message : DEBUG:pyModbusTCP.server:accept new connection from ClientInfo(address='192.168.1.20', port=33476) DEBUG:pyModbusTCP.server:Exception during request handling: NetworkError('recv return null') I tried to stop the codesys client and to restart it with these commands : Modbus_TCP_Client.xStop := True; // Or False Modbus_TCP_Client.Enable := True; // Or False Modbus_TCP_Server.Enable := True; // Or False I tried to confirm the error manually to force reconnection with: Modbus_TCP_Server_Motors.xConfirmError := TRUE; I tried also this command to STOP/RESET/START client and server (codesys side) but nothing happens : status_client := Modbus_TCP_Client.SetCommunicationState(eRequestedState := DED.DEVICE_TRANSITION_STATE.STOP); // .RESET & .START The answer of this function when executed is "status_client = NOT_SUPPORTED" It seems that is a socket problem, but I do not understand if it is on the client or server side. I tried a modbus simulator called "ananas.exe" and the result is the same. Impossible to get a modbus reconnection. What is different at the first connection and at a reconnection attempt ? Thanks for your help
Last updated: 2025-03-14

Post by fmon on Modbus TCP client reconnection problem ^{CODESYS Forge talk (Post)}
Hello, I am using codesys Modbus TCP client (4.4.0.0) to communicate with a python modbus server (package pyModbusTCP). I first start my python server on the distant machine. After a fresh codesys compilation, a plc connection/transfer and a PLC run, the modbus connection is OK. Every time in this context the connection is created correctly. When I shut down the server, the modbus connection falls, that is normal. When I restart the python server, impossible to recreate the modbus connexion. With the client autoreconnection, I see on my server that the client tries to connect but unsuccesfully. I have the following message : DEBUG:pyModbusTCP.server:accept new connection from ClientInfo(address='192.168.1.20', port=33476) DEBUG:pyModbusTCP.server:Exception during request handling: NetworkError('recv return null') I tried to stop the codesys client and to restart it with these commands : Modbus_TCP_Client.xStop := True; // Or False Modbus_TCP_Client.Enable := True; // Or False Modbus_TCP_Server.Enable := True; // Or False I tried to confirm the error manually to force reconnection with: Modbus_TCP_Server_Motors.xConfirmError := TRUE; I tried also this command to STOP/RESET/START client and server (codesys side) but nothing happens : status_client := Modbus_TCP_Client.SetCommunicationState(eRequestedState := DED.DEVICE_TRANSITION_STATE.STOP); // .RESET & .START The answer of this function when executed is "status_client = NOT_SUPPORTED". Is it normal ? It seems that is a socket problem, but I do not understand if it is on the client or server side. I tried a modbus simulator called "ananas.exe" and the result is the same. Impossible to get a modbus client reconnection. What is different at the first client connection and at a reconnection attempt ? Thanks for your help
Last updated: 2025-03-17

Post by otbeka on CAA File Handling: "Read only" error ^{CODESYS Forge talk (Post)}
Hi, On CODESYS V3.5.19.50 I am using the latest 3S File Access library (CAA File & CAA Types) to save and retrieve configuration data from the User Data section of an SD card, via file called config.txt. The application reads the file to memory once upon initialisation, and then the only other operation is overwriting the file with the updated configuration whenever the user changes the settings. An issue is ocurring, seemingly randomly, where the config.txt file, and all surrounding directories, cannot be written to by the unit, returning a READ_ONLY_CAA error upon file open. This sometimes does not clear even after power-cycling the PLC several times, yet checking the file permissions with ls -l shows normal read, write, and execute access. I am wondering if this is caused by the PLC itself or by an issue in my application. I have included my CAA File handler function block (SD_Card_Bin(FB).txt) and any associated types/calls below: TYPE ConfigData : STRUCT Config : ARRAY[0..256] OF STRING(64); NumberOfStrings : UDINT; END_STRUCT END_TYPE TYPE Buffer : STRUCT Data : ARRAY[0..SIZEOF(ConfigData)] OF BYTE; DataLength : UDINT; END_STRUCT END_TYPE A case within my MAIN PRG: mode.WriteConfigDataToFile: VisuElems.CURRENTVISU := 'Screen_Write'; IF xModeHasChanged THEN iErrorCount := 0; iRoute := 0; END_IF CASE iRoute OF 0: inBuffer := ConfigData_To_Buffer(GVL.UnitData); xConfigError := FALSE; xDataConfigured := FALSE; iRoute := 1; 1 : //Read Data from Card SD_Card_Bin.strFileName :=FileName; SD_Card_Bin.iFileOperation := 2; SD_Card_Bin(xExecute :=TRUE, WriteBuffer := inBuffer, xDone =>xDataConfigured, xError=>xConfigError, strErrorCodes=>strError); IF xDataConfigured THEN SD_Card_Bin(xExecute :=FALSE); IF xConfigError THEN iRoute := 32767; ELSE iRoute :=100; END_IF END_IF 100: // The end bCurMode := mode.DisplayProcessVariables; 32767: // Config error iErrorCount := iErrorCount + 1; IF iErrorCount > 2 THEN // Repeats 3 times, if no progress abandons and returns error bCurMode := mode.WriteError; ELSE iRoute := 0; // Try again END_IF END_CASE I'd like to rule out my application as the cause of this bug - help via comments or criticism would be greatly appreciated.
Last updated: 2025-03-19

Post by laurits on Max lines of code, codesys CNC ? ^{CODESYS Forge talk (Post)}
Hi, yes now its working, to get "QUEUE.bFull" to work, I've had to set the "QUEUE.nNumReservedEntries" to 3. (I tried different values here, only effect for larger values i can see is the the queue capacity gets smaller.) I've noticed the movement is slowing down when it reaches the end of the "fill Up", must be because of the "checkVelocity" can only see the current "QUEUE". Any way of solving this ? BUF : ARRAY[0..20000] OF SMC_GEOINFO; xp : ARRAY[1..100000] OF REAL; yp : ARRAY[1..100000] OF REAL; CASE iState OF 000: IF R_TRIG_bStart.Q THEN iState := iState + 1; END_IF bReady := FALSE; //initialize Queue GEO.dT1:=0; GEO.dT2:=1; GEO.dToolRadius := 0; GEO.dVel := 15000; GEO.dVelEnd := 15000; GEO.dAccel := 2000; GEO.dDecel := 2000; GEO.iObjNo := 0; GEO.piDestPos.dX := 0; GEO.piDestPos.dY := 0; QUEUE.bEndOfList := FALSE; QUEUE.nPastMarker := -1; QUEUE.nWritePos := 0; QUEUE.pbyBuffer := ADR(BUF[0]); n := 0; sMC_CheckVelocities(bExecute:= FALSE); SM3_CNC.SMC_SetQueueCapacity(ADR(QUEUE), SIZEOF(BUF)); QUEUE.nNumReservedEntries := 3; 001: FOR i := 1 TO SIZEOF(xp)/SIZEOF(xp[1]) DO xp[i] := UDINT_TO_REAL(i) * 0.01; yp[i] := UDINT_TO_REAL(i) * 0.01; END_FOR iState := iState + 1; 002: WHILE NOT QUEUE.bFull DO // when the Queue is full, wait until it has been processed by the following FBs n := n + 1; GEO.iSourceLine_No := n; GEO.piStartPos := GEO.piDestPos; // copy last destination GEO.iMoveType := LIN; // generate linear movement GEO.iObjNo := GEO.iObjNo + 1; // calculate number GEO.piDestPos.dX := xp[n]; // generate position GEO.piDestPos.dY := yp[n]; SMC_CalcLengthGeo(pg := ADR(GEO)); // calculate length of object with the help of the standard function SMC_AppendObj(poq:=ADR(QUEUE), pgi:=ADR(GEO)); //append object to queue IF n = UDINT_TO_DINT( SIZEOF(xp)/SIZEOF(xp[1])) THEN // all target positions processed QUEUE.bEndOfList := TRUE; iState := iState + 1; EXIT; END_IF END_WHILE sMC_CheckVelocities(bExecute:= TRUE, poqDataIn:= ADR(QUEUE)); bReady := TRUE; // Send message to smc_interpolator to start 003:
Last updated: 2025-06-04

Post by testlogic on Sending Sequential Modbus TCP Packets ^{CODESYS Forge talk (Post)}
I have a Modbus TCP slave device where I need to do sequential writes to the same register. The register I'm writing to is kind of like a command line, each packet is a command word encoded in Hexadecimal. I am having difficulty implementing this system in CoDeSys 3.5 SP19. I feel like the structure of the program should be something along the lines of (Pseudocode): ModbusTCPSend(Command Register, Command1) ModbusTCPSend(Command Register, Command2) ModbusTCPSend(Command Register, Command3) I have tried to implement this with a rising edge trigger wMot1OPCode := 16#E1; //Stop Motor & Kill Program xMot1SendOP := TRUE; //Send OP on rising edge xMot1SendOP := FALSE; //Reset wMot1OPCode := 16#9E; //Disable Motor xMot1SendOP :=TRUE; //Send OP on rising edge xMot1SendOP := FALSE; //Reset Where "wMot1OPCode" is the IO map for writing to the command register, and "xMot1SendOP" is the rising edge trigger for that modbus channel. However, this doesn't work. The device never responds to the modbus commands. It seems like the trigger variable is switched too quickly for modbus to send the packet. I know the modbus register is working, because I can set the channel to cyclic and the device will respond. However, I can't use this reliably because I need each command to be sent once, in order. Cyclic keeps re-sending the commands and seems like it could miss a command as well if one was sent in-between cycle time. I have also trying using the Application trigger as described by https://faq.codesys.com/pages/viewpage.action?pageId=24510480, but this is also not working for me. See attached picture for my FBD code. This seems like a simple function, I can't tell what I'm doing wrong here. Thanks for the help.
Last updated: 2024-03-06

Post by tk096 on High Cycle Times for SoftMotion_PlanningTask when using AxisGroup ^{CODESYS Forge talk (Post)}
Hi, under this circumstances the performance of a Raspberry Pi 4 should be sufficient to run a Softmotion robotics application. A closer look at the project would be required. Maybe you could contact the codesys support? Usually it is recommended to run the planning task cyclically every 2ms with task priority of 0 on a dedicated core. In the task configuration you can have a look at the average and maximum execution time of the planning task. You could use the function block SMC_TuneCPKernel (https://content.helpme-codesys.com/en/libs/SM3_Robotics/Current/SM3_Robotics/POUs/AdministrativeConfiguration/Computation/SMC_TuneCPKernel.html) to define suitable values for the parameters 'fSyncBufferDuration' and 'fPlanningInterval'. However, as previously mentioned, the performance of a Raspberry Pi 4 with realtime patch should be sufficient. The 'fPlanningInterval' parameter specifies the maximum planning step width in seconds. The cycle time of the planning task should not permanently exceed this value. A higher value reduces the computational effort, but can lead to a violation or no full utilization of the set limit values for velocity, acceleration and jerk. From a starting value of 0.016 seconds, the value should be increased gradually until the performance is acceptable. The parameter 'fSyncBufferDuration' specifies the size (in seconds) of the buffer between the planning and fieldbus task. The cycle time of the planning task must not exceed this value at peak times (this will lead to the error SMC_CP_QUEUE_UNDERRUN). A higher value can compensate for peaks in the cycle time of the planning task. At the same time, however, this also increases the latency for executing interrupts and aborting movements.
Last updated: 2024-03-22

Post by xcqt on Oop best practice ^{CODESYS Forge talk (Post)}
Hi all, I’m currently trying to improve my OOP structure in CODESYS and I’m looking for some input on how others approach this. I understand the basics like inheritance, interfaces, abstract FBs, methods, and properties, but I still struggle a bit with the overall architecture and what’s considered clean or scalable in bigger projects. As an example, I’m working on two different energy meter function blocks: FB_EnergyMeter_MQTT reads data from MQTT (strings) FB_EnergyMeter_Modbus reads data from Modbus (words) Both have their own Update() method and implement the same interface (something like IF_EnergyMeter). Later on, I’ll probably add more meter types, but they should all behave the same from the controller’s point of view. Now, there’s a FB_GridControl block that needs power data from these meters. I see two options here: Define the meter blocks inside FB_GridControl and call them directly (for example fbModbusMeter.UpdateModbus()). Keep the meter blocks outside and pass them into FB_GridControl as interface references, so the control block doesn’t know which specific type of meter it’s dealing with. Option 2 feels cleaner and more flexible to me, but I’m not entirely sure how to handle the data flow in that case. Should I pass the meter instance through an interface reference (REFERENCE TO IF_EnergyMeter)? Or is there a better way to link the external FBs to the control block? I’d like to hear how you structure this kind of setup or see an example from someone who has done something similar. EDIT: I think i need to do something like this fbModbusUpdateInput(wInput:= wWordValue); fbMqttUpdateInput(strInput:= strStringValue); IF bUseMqtt THEN Meter REF = fbMqttUpdateInput; ELSE Meter REF = fbModbusUpdateInput; END_IF fbControl.SetMeter(UsedMeter := Meter); Or am i thinking wrong? Thanks, Thomas
Last updated: 2025-10-16

Post by e13740e on Parameterized Property syntax for array element processing ^{CODESYS Forge talk (Post)}
Since parameterized (indexed) properties are not possible, I decided to use architectural approach "Indexing Property Adapter" to achieve the intended goal — avoiding code duplication for validated access to array elements. Essence: Create a Function Block Adapter (FB_PropertyAdapter) that encapsulates the logic for working with a single element of the target array (e.g., with one settings structure). Declare Properties inside the adapter block for accessing each individual field of the data structure. All validation logic is implemented within the Set accessors of these properties. Data Binding via VAR_IN_OUT: The adapter block receives a reference to a specific data element from the global array through its VAR_IN_OUT section, which ensures direct work with the original data without copying. Create an Array of Adapters: In the parent POU (e.g., FB_SettingsManager), an array of these adapter blocks is created — one for each element of the global array that needs to be managed. Initialize Bindings: In a FOR loop, each adapter instance from the array is given a reference to the corresponding data element. Result: This approach allows accessing the data via the index of the adapter array, and then through the property name, which simulates the behavior of an indexed property: MyAdapterArray[Index].MyProperty Thus, the validation and data access logic is written only once inside the adapter block and is then reused multiple times by creating instances of it in an array. This completely solves the problem of code duplication while providing a clean, scalable, and object-oriented architecture compatible with standard CODESYS features. Question closed.
Last updated: 2025-10-19

Post by bschraud on runtime received SIGABRT ^{CODESYS Forge talk (Post)}
Hallo, seit der Umstellung meines Projektes auf die aktuelle Codesys Version mit aktuellen Bibliotheken und Aktualisierung der Runtimer Version bekomme ich im Zeitraum 15min bis 1h nach Neustart des Target Systems folgende Fehlermeldung: runtime received SIGABRT - system may be in an inconsistent state Der Fehler kommt auch nach dem Start des Systems ohne eine Benutzeraktion zuverlässig, aber in unterschiedlichen Zeiträumern. Hier sind die Logs und Daten, die ich dazu ermitteln konnte: $ tail -f /var/opt/codesys/codesyscontrol.log 2025-04-03T06:54:37.659Z, 0x0000100c, 1, 0, 0, Visu_PRG: Creating Client for Extern-ID: 594337835 2025-04-03T06:54:37.660Z, 0x0000100c, 1, 0, 0, Visu_PRG: Creating Client successful for Extern-ID: 594337835 Returned IEC-ID: 0 2025-04-03T07:01:38.135Z, 0x00000103, 65544, 1, 0, runtime received SIGABRT - system may be in an inconsistent state * We recommend a reboot of the controller now! 2025-04-03T07:01:38.135Z, 0x00000111, 8, 260, 3, #### Exception: HANDLED EXCPT* <excpt>NonContinuable</excpt> in CH_COMM_CYCLE 2025-04-03T07:02:18.181Z, 0x00000103, 65544, 1, 0, runtime received SIGABRT - system may be in an inconsistent state * We recommend a reboot of the controller now! 2025-04-03T07:02:18.181Z, 0x00000111, 8, 260, 3, #### Exception: HANDLED EXCPT* <excpt>NonContinuable</excpt> in CH_COMM_CYCLE $ vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 1 0 0 271120 33976 342284 0 0 135 2 2387 4751 10 7 82 1 0 1 0 0 271024 33976 342380 0 0 0 0 10163 20427 10 9 81 0 0 1 0 0 271056 33976 342380 0 0 0 0 8455 16869 9 5 86 0 0 0 0 0 271040 33976 342380 0 0 0 0 8674 17484 9 4 87 0 0 0 0 0 271072 33976 342380 0 0 0 0 10070 20350 7 7 87 0 0 1 0 0 271040 33976 342380 0 0 0 0 10354 20802 10 6 84 0 0 0 0 0 271072 33976 342380 0 0 0 0 8401 16923 8 6 86 0 0 $ vcgencmd measure_temp temp=56.9'C $ uname -a Linux PAC4 5.10.103-v7+ #1529 SMP Tue Mar 8 12:21:37 GMT 2022 armv7l GNU/Linux CODESYS V3.5 SP21 Runtime: Codesys control for Raspberry Pi MC SL V 4.13.0.0 Hinweise auf ein instabiles OS oder instabile Netzwerkverbindungen konnte ich keine finden. In dmesg und im syslog gibt es keine Auffälligkeiten. Die anderen Posts zu diesem Thema wurden nicht beantwortet. Hat jemand einen Tip, wie man an das Problem herangehen kann? Vielen Dank
Last updated: 2025-04-03

Post by sahin6033 on DSE M840-001-02: DSEServiceTool transfers CodesysApp.pkg successfully, but device shows “No application loaded ^{CODESYS Forge talk (Post)}
Hi, I am trying to load a test application into a DSE M840-001-02 display, but after reboot the device still shows: “No application loaded” I would like to understand whether the problem is in my project, the package creation process, or firmware/runtime compatibility. Hardware Device: DSE M840-001-02 Firmware used: M840 MKII Firmware File v4.1.2 Software CODESYS V3.5 SP12 (32-bit) DSE CODESYS Package v1.5.44 DSEServiceTool What I did Created a new empty Standard Project Selected target/template: M840-02 V4.1 Used a minimal ST program only: PROGRAM PLC_PRG VAR xAlive : BOOL := TRUE; END_VAR Confirmed: project builds PLC_PRG is assigned to MainTask created Boot Application Generated CodesysApp.pkg Put the M840 into bootloader mode Sent the package using DSEServiceTool DSEServiceTool result Transfer completes successfully and I get: connection accepted 100% download package ACK <status>OK</status> ** Example log:** Searching for controllers.... sendPackageToController: waiting for incoming data connection... sendPackageToController: connection accepted... <status>Downloading</status> <percent>20</percent> <percent>40</percent> <percent>90</percent> <percent>100</percent> sendPackageToController: sent 112cb8 bytes OK Package ...\CodesysApp.pkg transferred to controller c0a80101 OK sendPackageToController: package ACK <status>OK</status> Actual result After reboot, the display still shows: “No application loaded” Additional issue I also saw earlier At one stage I also had these fatal errors in CODESYS: [FATAL ERROR] Unresolved reference: 'IOMGRLOCKENTER' [FATAL ERROR] Unresolved reference: 'IOMGRLOCKLEAVE' I checked library versions and adjusted them to: IoDrvBase = 3.5.5.0 IoStandard = 3.5.10.0 Also, I am using CODESYS SP12, which I understand is the correct version for DSE M840. My questions If DSEServiceTool shows Status OK and package ACK, but the device still says “No application loaded”, does that mean: the .pkg was transferred but not accepted as a valid application? the package was built incorrectly? the boot application / runtime / firmware versions are still mismatched? What is the correct procedure to generate CodesysApp.pkg for M840-02 V4.1? Is there any known compatibility issue between: DSE CODESYS Package 1.5.44 M840 MKII Firmware 4.1.2 CODESYS 3.5 SP12 Has anyone successfully loaded even a minimal empty test project into M840-001-02, and if so, what exact versions/process did you use? Any help would be appreciated.
Last updated: 2026-03-17

Post by dwpessoa on CNC Jumps G20 - SMC_NCInterpreter and long time to process ^{CODESYS Forge talk (Post)}
I am studying and developing a Softmotion+CNC system for a machine that executes multiple pieces. The G code program is written by the machine operator and each cycle execute 1 piece. The programs are large, exceeding 1000 lines and using up to 8 axes (X, Y, Z, A, B, C, P and Q). The machine needs to run cyclically, executing N pieces (selected by the Operator)... so I tested it using Looping and counters (G36 G37 and G20) and it worked, but it takes a long time to process, and the more pieces I need, the longer the processing time and this is totally impracticable. I found this solution which was very good, and for a few cycles it works well, but for 99999 pieces of a program with 1000 lines, it doesn't work very well... Another solution I tested is to maintain the interpolator with an automatic restart, that is, I load the program without looping (without G20) and give it another start as soon as it finishes. This partially resolved it, but there is still a delay in processing SMC_NCInterpreter in each restart :(. Another solution I thought of is to manually create the SMC_GEOINFO structure and then reuse it, avoinding the Interpreter, but reading the documentation and checking the structure filled by standard blocks, I noticed that there doesn't seem to be a "JUMP" function in the structure! In other words, the SMC_NCInterpreter actually keeps copying and copying the program section for each jump (G20)... If I repeat a 10-line program 1000 times, I will have a structure with more than 10000 lines... possibly this is the cause of take so long to process. Has anyone ever had a problem like this? I believe the same thing happens with typical applications with manipulator robots using Codesys in continuous cycles, and I would like to know if there is any solution, or even if I am misinterpreting the G20 question in SMC_GEOINFO. Thanks!
Last updated: 2023-09-20

Post by mgabryel on Problems with CAN 2.0 comunication on Wago PLC (Codesys 3.5) ^{CODESYS Forge talk (Post)}
Hello, I am trying to program CAN Bus comunication on WAGO PLC (more precisely on WAGO Touch Monitor model TP600). I am using for this purpose library "WagoAppCanLayer2" from Wago company. My IDE for programming this device is CODESYS V3.5 SP19 Patch 2 + (64-bit). My program is written in Structured text using function blocks from previously mentioned library. Here is code of this program: 1) Variables declarations: PROGRAM PLC_PRG VAR oOpenInterface : WagoAppCanLayer2.FbCanL2Open :=( udiBaudrate := 125000 ); xInterfaceIsOpen : BOOL; sInterfaceInfo : STRING; oReceive : WagoAppCanLayer2.FbCanRx29BitFrame :=( xBufferMode := FALSE, wCanId := 16#181 ); xRecv : BOOL; sReceiveInfo : STRING; oSend : WagoAppCanLayer2.FbCanTx29BitFrame :=( dwCanId := 16#100, //was 16#201 xRtrFrame := FALSE ); xSend : BOOL; sSendInfo : STRING; oCanDiag : WagoAppCanLayer2.FbCanErrorInfo; xRst : BOOL; aSendData : ARRAY [1..8] OF BYTE; bSendLen : BYTE; TON_0 : TON; TON_1 : TON; END_VAR 2) Program body: oOpenInterface( xEnable := NOT xInterfaceIsOpen, I_Port := IoConfig_Globals.WAGO_CAN_LAYER2_DEVICE ); sInterfaceInfo := oOpenInterface.oStatus.GetDescription(); xInterfaceIsOpen S= oOpenInterface.xValid AND NOT oOpenInterface.xError; oReceive( xEnable := xInterfaceIsOpen, I_Port := IoConfig_Globals.WAGO_CAN_LAYER2_DEVICE, xRxTrigger := xRecv ); sReceiveInfo := oReceive.oStatus.GetDescription(); IF NOT xRecv THEN IF oReceive.bRxNBytes > 0 THEN oReceive.aRxBuffer[1]; oReceive.aRxBuffer[2]; oReceive.aRxBuffer[3]; oReceive.aRxBuffer[4]; oReceive.aRxBuffer[5]; oReceive.aRxBuffer[6]; oReceive.aRxBuffer[7]; oReceive.aRxBuffer[8]; END_IF xRecv := TRUE; END_IF aSendData[1] := 224; aSendData[2] := 13; aSendData[3] := 14; aSendData[4] := 15; aSendData[5] := 222; aSendData[6] := 13; aSendData[7] := 14; aSendData[8] := 15; bSendLen := 8; TON_0(IN:= NOT TON_1.Q, PT:= T#2S , Q=>xSend, ET=> ); TON_1(IN:= TON_0.Q, PT:= T#2S , Q=>, ET=> ); oSend( xEnable := xInterfaceIsOpen, I_Port := IoConfig_Globals.WAGO_CAN_LAYER2_DEVICE, aTxBuffer := aSendData, bTxNBytes := bSendLen, xTxTrigger := xSend ); sSendInfo := oSend.oStatus.GetDescription(); oCanDiag( xEnable := TRUE, I_Port := IoConfig_Globals.WAGO_CAN_LAYER2_DEVICE, xTriggerResetCounter := xRst, xValid=> , xError=> , oStatus=> , wBusState=> , wBusDiag=> , uiRxOverflowsL2=> , uiTxOverflowsL2=> , uiRxOverflows=> , uiMsgTimeouts=> , uiBusOffs=> , uiBusWarnings=> ); Program first opens comunication on CAN 2 device and then periodically try send one CAN data frame. After starting program CAN 2 interface is properly open. The xSend variable is toggling with period 2s. When program sends data an "Tx overflow" error appears. When I am watching CAN_H line on DSub 9 socket i am not able to see proper CAN frames - see screenshot attached to this message. Could somebody help me determine what is wrong with this program. Best regards
Last updated: 2024-08-02

Post by gustavocsw on MQTT memory leak problem ^{CODESYS Forge talk (Post)}
Hello everyone, I'm using the IoT Library to implement the MQTT communication with my local broker server in order to publish and subscribe at specifics topics to share and consume information about my application. But, it seems that are occurring some memory leak problem in a "high" frequency (more than 10 Hz) subscribe process. I follow the same method as in IoT Lib exemples, and at first looks perfect but my PLC was rebooting frequently and when I check its memory usage that was increasing as fast as the subscribe massage was sent. I'm using a WEG PLC410 and a WEG PLC500, and this error occurred in both of them (including in CODESYS Control Win x64). The application sends to the system a message JSON with the float payload Ex. {"data" : 0.8500}, but this happens with a INT, or BOL as well. I use the follow code in my application to find the value: //FindFirstValueByKey VARs PROGRAM JSON_VELO VAR //------Setting the JSON Subscriber to Set the Relay Value jsonDataVelo : JSON.JSONData; jsonByteArrayReaderVelo : JSON.JSONByteArrayReader; xST1okVelo : BOOL; FindFirstValueByKeyVelo : JSON.FindFirstValueByKey; jsonElementVelo : JSON.JSONElement; xDoneReaderVelo : BOOL; xDoneFindVelo : BOOL; //STRING and WSTRING for Subscribe the massage sPayloadJsonVelo : STRING := 'opa'; psPayloadJsonVelo : POINTER TO BYTE := ADR(sPayloadJsonVelo); //wsPayloadJsonRelaySet : WSTRING := "opa"; wsPayloadJsonVelo : WSTRING := STRING_TO_WSTRING('opa'); pwsPayloadJsonVelo : POINTER TO WORD := ADR(wsPayloadJsonVelo); lrVelo : LREAL; xKeepAliveVelo : BOOL; xSetVelo : BOOL; RSSet : RS; LIMPAR : STRING; //Find the msg end sFindVelo : STRING := '}'; psFindVelo : POINTER TO STRING := ADR(sFindVelo); iLenVelo : INT; iSizeVelo : INT := 12; udiContMsg : UDINT; END_VAR // FindFirstValueByKey CODE // Relay Set configuration xSetVelo := MQTT_SUBSCRIBER.RSVelo.Q1; IF xSetVelo THEN xKeepAliveVelo := TRUE; END_IF IF xKeepAliveVelo THEN udiContMsg := udiContMsg + 1; iLenVelo := TO_INT(StrLenA(psPayloadJsonVelo)); iSizeVelo := iLenVelo - TO_INT(MQTT_SUBSCRIBER.udiPayloadSizeVelo); StrDeleteA(psPayloadJsonVelo,iSizeVelo,iLenVelo); wsPayloadJsonVelo := STRING_TO_WSTRING(sPayloadJsonVelo); pwsPayloadJsonVelo := ADR(wsPayloadJsonVelo); //MQTT.ConvertUTF8toUTF16(sourceStart:= ADR(sPayloadJsonVelo), targetStart:= ADR(wsPayloadJsonVelo), dwTargetBufferSize:= TAM, bStrictConversion:= 1); //Reset jsonByteArrayReader jsonByteArrayReaderVelo ( xExecute := TRUE, pwData := pwsPayloadJsonVelo, jsonData := jsonDataVelo, xDone => xDoneReaderVelo ); FindFirstValueByKeyVelo( xExecute := xDoneReaderVelo, wsKey := "data", diStartIndex:= 0, jsonData := jsonDataVelo, jsonElement => jsonElementVelo, xDone => xDoneFindVelo ); IF xDoneFindVelo THEN lrVelo := jsonElementVelo.value.lrValue; //Reset jsonByteArrayReader jsonByteArrayReaderVelo ( xExecute := FALSE, pwData := pwsPayloadJsonVelo, jsonData := jsonDataVelo, xDone => xDoneReaderVelo ); FindFirstValueByKeyVelo( xExecute := FALSE, wsKey := "data", diStartIndex:= 1, jsonData := jsonDataVelo, jsonElement => jsonElementVelo, xDone => xDoneFindVelo ); xKeepAliveVelo := FALSE; GVL.xSetVeloRead := TRUE; END_IF END_IF And this to subscribe at the topic: //SUBSCRIBE VAR: //----------------- Subscribe Velocity ----------------------- MQTTSubscribeVelo : MQTT.MQTTSubscribe;//Variable MQTTSubscriber block -X - function-X wsTopicSubscribeVelo : WSTRING(1024) := "CORE/odometry/GET/data/simp"; // Topic to publish a message sSubscribeMassageVelo : STRING; udiPayloadSizeVelo : UDINT; xSDoneVelo : BOOL; xSErrorVelo : BOOL; xReceiveVelo : BOOL; eSTypeVelo : MQTT.MQTT_ERROR; eSMQTTErrorVelo : MQTT.MQTT_ERROR; RSVelo : RS; udiCont : UDINT; //SUBSCRIBE CODE: MQTTSubscribeVelo( xEnable:= MQTT_CLIENT.xConnection_Broker AND NOT xSErrorVelo AND NOT JSON_VELO.xKeepAliveVelo, pbPayload:= JSON_VELO.psPayloadJsonVelo, udiMaxPayloadSize:= SIZEOF(JSON_VELO.sPayloadJsonVelo), udiPayloadSize => udiPayloadSizeVelo, mqttClient:= MQTT_CLIENT.ClientMQTT, wsTopicFilter:=wsTopicSubscribeVelo, xDone => xSDoneVelo, xError=> xSErrorVelo, xReceived => xReceiveVelo, eMQTTError=> eSMQTTErrorVelo ); RSVelo(SET := xReceiveVelo, RESET1 := JSON_VELO.xKeepAliveVelo);
Last updated: 2024-09-09

Post by george32 on Readable IO names ^{CODESYS Forge talk (Post)}
Hello Folks, I have a quite basic understanding of how PLC programming works. However I keep getting stuck on 1 problem I could not get my head around. The problem is as follow: I have a PLC with 60 IO (20 inputs, 40 outputs). Each IO is defined as a function block. Furthermore I have an external IO card connected trough a CanBus connection. This IO card has 4 analog input channels (USINT), 4 digital inputs (Bool) and 4, digital outputs (Bool) Because I have 2 different components which both has data have I made 4 arrays to store the data off every component in one variable. PLC_Input: Array [1..20] of BOOL; PLC_Output: Array [1..40] of BOOL IOCard_Input: Array [1..8] of BOOL IOCard_Output: Array [1..4] of BOOL Because the control and reading of the different in and outputs is done by a TCP connection I want to use some kind of enumeration or struct to give each index a name so that my main would be a little bit more readable instead of all the magic numbers. Also this would make my program more dynamic for the furter in case I need to changes some in the IO nummers. For example: pump is placed on the fysical terminal strip number place 54, which is the 3th output of the IO card in the program: if I am sending a message with value 54 I would like to control IOCard_Output[3]. If there is a solution or methode to get this done, I can eventually do the following in my main program: IOCard_Output[Pump]. I have tried the following: IOCard_Output[Pump - 51] with an enumration but this keeps raising an error I hope some of you could help me further with this problem. In gross lines: I want to couple all the different IO to a more readable name and this readable name should control the right Array index Thanks in advance, George
Last updated: 2024-09-26

Post by patrik on Wish: CODESYSControl.cfg - again ^{CODESYS Forge talk (Post)}
Really good post. I hope that it gets seen by CoDeSys staff. I often find the documentation lacking when it comes to using CoDeSys in more complex ways. If using standard "basic PLC functionality", then it's fine and functions are documented in a sufficient way. Once you go outside of that bubble then I find the documentation not enough. CODESYSControl.cfg is a good example of this. And why isn't more of this integrated in the IDE. like changing port of the webserver. Why is it hidden in this file and not accessible through the IDE. It feels like a layer of complexity purposely left in so you don't change it if you don't know what you are doing. Like the argument is if you have the know-how to find the file you have the know-how to edit it. I find the documentation lacking when it comes to more complex libraries too. Like the element collections library. there is parameters I still don't quite know what they do. I can't find any documentation about them. There is an example project to download from CoDeSys so you can see how you are supposed to set your factories up. I leave some parameters like it is in the example. Should I? I don't know. Does it work. Yes. But I could perhaps create memory leaks if I get something wrong and I don't see that until way later. In the create method of your element factory you have a function called __vfinit and you just have to accept that it works. Why can't I get insight in what it does through documentation? Don't CoDeSys want us to know how these work so we can't use them to accidentally break something? I find the error logging lacking too. I've had the CoDeSys service crash but it doesn't say why. I've seen windows noticing the crash but no error code was sent or error message. Also in my current issue where the application fails to start after power outage. I can see in the log that it fails to load retain in the application as one log entry and application failing to start as another. But why? Why does loading the retain fail? give me more information! Is it just a skill issue with me? I don't know. If it is then I'd still want CoDeSys to step up their game when it comes to documentation. I'm sorry if a lot of frustration comes though in this post. I really like the product and what I can do with it compared to other PLC brands.
Last updated: 2024-11-21

Post by solidlogicguy on Little endian to Float from Modbus RTU ^{CODESYS Forge talk (Post)}
Hello, I got a device from which I require to read values from I am using a WAGO PLC 750-8212 and I am communicating through Modbus Master FUNCTION BLOCK from library WagoAppPLCModbus in Codesys 3.5 to this device. I already receive data from the device that is a CVM to monitor voltage from a fuel cell. The technical support of the company that makes these devices says that the data is sent in little endian form. And I want to convert it to a float value. The tech support sent me the next instructions of how to do it but I am new using codesys, so any advice or help I will really appreciate so much. Message from tech support: The process is complicated, better to do it with already implemented library in the language/program you use. Basically the process should be next: To convert the two Modbus registers containing parts of a 32-bit float in little-endian byte order to a floating-point number using mathematical operations, you first need to combine the two 16-bit integers (assuming reg1 is the lower word and reg2 is the higher word) and then interpret the result according to the IEEE 754 standard. Given: - Register 192 (reg1) = 4096 - Register 193 (reg2) = 14884 Step 1: Combine the two registers. Since we are dealing with little-endian byte order, reg2 is the high word, and reg1 is the low word: combined = reg2 * 2^16 + reg1 combined = 14884 * 65536 + 4096 combined = 975175680 + 4096 combined = 975179776 Step 2: Convert the combined value to binary: combined_binary = '1110101101011100000000000000000' Step 3: Split the binary into IEEE 754 components: Sign bit (1 bit): 0 Exponent (8 bits): 11101011 Mantissa (23 bits): 01011100000000000000000 Step 4: Convert the binary exponent to decimal and subtract the bias (127 for 32-bit floats): exponent = int('11101011', 2) - 127 exponent = 235 - 127 exponent = 108 Step 5: Calculate the mantissa as a fraction: The mantissa in IEEE 754 format is the fractional part after the leading 1 (which is implicit). Therefore, we need to convert the binary mantissa to decimal and add the implicit leading 1: mantissa_fractional = 1 + int('01011100000000000000000', 2) / 2^23 mantissa_fractional = 1 + 18688 / 8388608 mantissa_fractional = 1 + 0.002227783203125 mantissa_fractional ≈ 1.002227783203125 Step 6: Combine the sign, exponent, and mantissa to get the float value: float_value = (-1)^0 * mantissa_fractional * 2^exponent float_value = 1 * 1.002227783203125 * 2^108 Because the exponent is quite large, the resulting float value is a very large number.
Last updated: 2023-12-15

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