Post by i-campbell on Publish a JSON payload via MQTT Publish (using IIot Libraries) ^{CODESYS Forge talk (Post)}
your are sending as a WSTRING which is UTF16, but your receiver is interpriting as UTF8. Change the receiver to use UTF16, or better change your sender to convert to UTF8. You publish the entire storage space (SIZEOF) Instead of the number of bytes of actual text (StrLenA) try using utf8JsonData : STRING(2000); JSON.Stu.ConvertUTF16toUTF8( ADR(wsJsonData), ADR(utf8JsonData), SIZEOF(utf8JsonData) ); and change your publish to mqttPublish( mqttClient:=mqttClient, pbPayload:=ADR(utf8JsonData), udiPayloadSize:=To_UDINT(JSON.Stu.StrLenA(ADR(utr8JsonData))), wsTopicName:=topic, mQTTPublishProperties:=mqttPublishProperties );
Last updated: 2024-04-10

Post by corriibme on Setting array values with JSON Utilities SL ^{CODESYS Forge talk (Post)}
I have been trying to set an array value to a JSON structure of this form: {"key": [1,2,3,4]} While I have been able to create the key and set its value to an empty array, I've not had any luck in putting any value in that array. objindex:= fb_JBuilder.SetKeyWithArray("Key6", diParentIndex := diRootIndex); objindex2:= fb_JBuilder.SetValue(value:= iValue2, diParentIndex:= objindex); iValue2: ARRAY[0..3] OF INT:= [1,2,3,4]; The two lines of code above produce {"key6": []} . The second line essentially has no effect.
Last updated: 2024-05-12

Post by akrawczyk on Dynamically enabling/disabling Modbus slave devices in runtime (performance issue with timeouts) ^{CODESYS Forge talk (Post)}
Hi everyone, I'm working on a CODESYS-based project running on a Weintek cMT2078X HMI with a built-in CODESYS runtime. The system communicates with multiple Modbus RTU slave devices, arranged in a cascade. The number of connected units can vary between 2 and 8, depending on the installation. Each slave has 17 Modbus channels, which are polled cyclically every 5 seconds. The issue is that when fewer devices are physically connected (e.g. only 3 out of 8), the Modbus master still attempts to communicate with all configured slaves. This leads to massive delays due to timeouts (currently 200ms per channel). For one disconnected device, that’s: 17 × 200ms = 3.4 seconds of delay per polling cycle, and this quickly multiplies with each additional missing slave. This behavior significantly degrades the system's performance and responsiveness. We attempted a workaround where we tried to trigger polling based on a variable in the PLC program, but this caused instability and even led to hardware hangs/freezes on the cMT2078X – likely due to clashes in how the Modbus polling engine and program logic interact at runtime. My main questions are: Is there a way in CODESYS to dynamically enable/disable Modbus slave devices at runtime, using a BOOL or INT variable (e.g. indicating number of active slaves)? Can devices or channels be conditionally polled or temporarily disabled without removing them from the device tree? Are there any best practices or examples for handling variable numbers of Modbus slaves in scalable systems like this? Would splitting communication across tasks or interfaces help reduce the impact of timeouts? Any advice, documentation references, or architectural suggestions would be extremely helpful. I'm looking for a robust way to dynamically scale slave polling without degrading system stability or performance. Thanks in advance!
Last updated: 2025-08-11

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 manuknecht on Maximum dynamic limits of MC_MoveLinearAbsolute and MC_MoveLinearRelative ^{CODESYS Forge talk (Post)}
Hello all I use an axis group with two linear axes in a kinematic system. Using MC_MoveLinearAbsolute and MC_MoveLinearRelative, I am trying to realise dynamic movements (set velocity: 1 m/s, set acceleration: 30 m/s^2) with the highest possible jerk, as I want to compare this with a movement with a trapezoidal velocity profile. However, my measurements show that the axes accelerate with a maximum jerk of approx. 800 m/s^3, even if the value in the function block was set to 10,000 m/s^3. I have already increased the dynamic limits of the two axes accordingly (Velocity: 5000 u/s, Acc-/Deceleration: 250'000 u/s^2, Jerk: 100'000'000 u/s^3, where 1 u = 1 mm), but this had no effect. I have checked the input parameters of the function blocks and the VelFactor, AccFactor and JerkFactor factors are all set to the maximum (value 1). Reducing the cycle time has resulted in a higher jerk, but as we are already working with a cycle time of 1 ms, there is nothing more that can be done here. The axes themselves are still a long way from drawing the maximum current, which is why I assume that this should not be a problem either. Are there other factors or parameters that influence the dynamic limits and therefore allow faster movements? The PLC I am using is a Raspberry Pi 4 and Codesys V3.5 SP20 with all libraries up to date. Thanks in advance Manuel
Last updated: 2024-05-08

Post by ivanh on kepware minimun privilege ^{CODESYS Forge talk (Post)}
Hello everyone, I’m integrating Codesys with Kepserver using the Kepware driver for Codesys, and I need to configure a user account with the minimum necessary privileges to read and write to the tags on the PLC, without using the internal OPC UA server of Codesys. However, despite not assigning the Modify permission, Kepware still allows writing to the tags. What are the minimum required permissions to ensure that writing is only allowed when necessary, and how can I prevent other permissions from being overridden? Any guidance would be greatly appreciated.
Last updated: 2024-08-12

Post by varshag on Trying to pull Logged In user details and certain other variable values and in turn log to a database ^{CODESYS Forge talk (Post)}
Hello All, I am new to Codesys and am trying to create a simple project which would let me log to a 6 column database table. I can use a push button on Visualization to initiate the logging. Column 1:Timestamp Column 2:Full name or Initials of Logged in operator Column 3,4,5,6: Certain variables Any help is highly appreciated. Thank you.
Last updated: 2024-11-07

Post by dogulas on Removing a symbol from the IEC Symbols Editor grid ^{CODESYS Forge talk (Post)}
In the CODESYS IDE I have several symbols defined and I have IEC Symbol Publishing installed. On the IEC Symbol Publishing window and under the IEC Symbols Editor tab, I have dragged symbols from the tree on the left to the grid on the right. All this works fine. Now I want to remove one of the symbols from the grid on the right and I cannot see any way to do this. How can I remove a symbol from the grid on the right once I've added it?
Last updated: 2025-02-07

Post by altus22 on RemoteTargetVisu creates Unresolved Reference ^{CODESYS Forge talk (Post)}
In order to set the placeholder to empty, open the Library Manager and click on Placeholders in the Library Manager ribbon. If you left click in the library column for CmpEventMgr Implementation, it will show you the available library versions for CmpEventMgr Implementation. To update the runtime, open the Project menu and select Project Environment. That window will show you the current version of CmpUserMgr Implementation and if there is a newer version available in the Recommended column.
Last updated: 2025-04-17

Post by griinde on display values with frames ^{CODESYS Forge talk (Post)}
i want to make a frame for use multiple places for showing pressure and temperature. ive tried to decleare a variable in the frame config, if i put a fixed value in the value text field it show correct until i simulate. and if i point to a variable i gvl it show the name of the variable, and when i simulate it shows rValue. is there a way to do what i want?
Last updated: 2025-08-16

Post by arvindkumar on Wago plc not going back to RUN Mode after Power failure ^{CODESYS Forge talk (Post)}
Hi im using wago pfc750-8207 plc and my programming software was codesys v2.3, im facing some issue in my plc after power failure my plc not going back to run mode sometimes, i did sourecode download, boot application created and still facing this issue, out of 10 power failure 8 times its going to run mode some time its missing to go run mode and only sys indication is in on condition Kindly please help me.
Last updated: 2023-12-15

Post by felipemsgarcia on Edge Gateway online, but PLC is not online ^{CODESYS Forge talk (Post)}
Hello, I couldn't figure what/where the issue was, so I deleted everything from automation server and reinstalled the edge gateway and did the process again. It worked for about a month and then it stopped working again. It presents the same symptom, edge gateway is online but I can't connect to the PLC. Any idea of what could be the issue? Thank you!
Last updated: 2024-01-09

Post by wind-11 on Problem with simulation Modbus ^{CODESYS Forge talk (Post)}
Hello everyone, I encountered a problem in the simulation while working. In a test project we set up a Modbus connection. We wanted to simulate this with test values. The connection also worked, but unfortunately the values are frozen and do not report any “current data”. (Picture attached) Since these are my first points of contact with Codesys and my colleague continues to work elsewhere, I was hoping that someone here might have an idea. Kind regards and thanks in advance.
Last updated: 2024-03-22

Post by yannickasselin on How to sort JSON object in codesys ^{CODESYS Forge talk (Post)}
Just adding: sSubscriberdata := ''; Right before your memcopy should fix the extra characters. It is because your are copying 36 characters into a string which can contain more than 36 characters and there is garbage left in the extra characters. Regarding the parsing of json, I usually build a structure that mirrors the json data and use the available methods in the IIoT library to parse the data and fill the structure.
Last updated: 2024-05-08

Post by ph0010421 on Windows 11 and SP17 ^{CODESYS Forge talk (Post)}
Hello New W11 machine. I've tried installing and the 'Codesys installer' appeared, which basically failed. This was the exe from the Store. I've now tried installing with an old copy of SP17, which didn't try and use the Codesys installer, but has hung at the 'Install all packages added to the setup' stage. Has the exe been updated to use the Codesys installer? What is the installer? Do we think it'll work on w11? thanks, Paul
Last updated: 2024-06-12

Post by ranadheer on Request to share documents about SoftPLC Extension SL ^{CODESYS Forge talk (Post)}
Hello Everyone Our team is planning to begin an industrial automation project and we are currently evaluating the use of SoftPLC Extension SL as a potential solution. As we are in the early stages and have yet to start the implementation, we kindly request access to official reference documents, technical manuals, and datasheets relating to SoftPLC Extension SL. Thank you very much for your assistance. We look forward to your response.
Last updated: 2025-10-18

Post by nehaltrivedi96 on Modbus connection via Qronox PCD3 M6893 ^{CODESYS Forge talk (Post)}
Hello, I am currently scaling 4-20mA signals and the scaled output (temperature) has to be sent via modbus protocol to a tool like doctor modbus or modbus poll. I have defined my inputs as real as and the output is also real, but to send this output via modbus it has to be of word. So how will i convert real into word and then send the generated output via modbus?
Last updated: 2026-02-18

Post by simotion on Pointer to Softmotion axis ^{CODESYS Forge talk (Post)}
In my projet I use Softmotion. There are several Softmotion axis (type SM_Drive_Virtual). In the Global Variable List I have an array of pointers to the adress of the Axis. Axis : ARRAY[1..iMaxCntAxes] OF POINTER TO AXIS_REF_SM3 := ADR(AX01_Axis), // [1 ADR(AX02_Axis), // [2] This works, but when compiling I get the message : . [WARNING] E3D: GVL Device: PLC Logic: Application: C0564: A reference to uninitialized variable AX01_Axis is used for initialization of Axis. Accessing the uninitialized variable may result in unexpected behavior. [WARNING] E3D: GVL Device: PLC Logic: Application: C0564: A reference to uninitialized variable AX02_Axis is used for initialization of Axis. Accessing the uninitialized variable may result in unexpected behavior. Is there a way when initializing to force the hardware (softmotion axis) to first initialize and then the Global Variable List?
Last updated: 2023-10-25

Post by fredruel on ModbusServer became unreachable if reach maximum of 16 byClientConnections ^{CODESYS Forge talk (Post)}
Hello Fraziersedge, the solution of Codesys might be to update your codesys to the lastest version but it was not possible for us. In our Codesys V3.5 SP9 patch 8 I was able to fix this bug. I change my ModbusTCP slave component version or one of the sub component version (ex: SysSocket). Look at the picture in attachement that's the receipe that have work for us. When I got the bug my version of ModbusTCP slave was 3.5.5.0 with SysSocket at 3.5.6.0 and I change to ModbusTCP slave 3.5.14.0 with same version 3.5.14.0 of SysSocket event if I still use codesys V3.5 SP9 patch 8.
Last updated: 2024-08-27

Post by sigurdrb on OPC server in "Communication manager" ^{CODESYS Forge talk (Post)}
Hi! I was thinking of switching the OPC server config from "Symbol Configuration" to the "Communication manager" in the device tree. I Have a lot of arrays of structs that I have previously declared in the "Persistent Variable" object in the device tree. It seems as it is not supported to directly expose persistant variables to the OPC server like the "older" way of doing it in the symbol config. Is this correct? Do you recommend to just do it the old fashioned way, or should I edit the structure of the global variable list / persistant data / OPC server and set up the OPC server from the "Communication manager" object?
Last updated: 2025-01-20

Post by pernockham on Trend legend naming and access/config to/of trend/legend-variables ^{CODESYS Forge talk (Post)}
Trying the web-version of trend-data. This seems to be a impressive tool, but I lack/cant find a number of what I would think are important parts. There does not seem to be a way to get away from the dot.notated variable naming in the legend.. A developer might want the dot-notation but an end-customer will surely not. For instance I want to display 12 temperatures, instead of t1, t2 etc.. they will be named. gvl_io.unit[1].trend.temps.t1_a gvl_io.unit[1].trend.temps.t1_b gvl_io.unit[1].trend.temps.t1_c gvl_io.unit[1].trend.temps.t2_a .. gvl_io.unit[1].trend.temps.t4_b.. gvl_io.unit[1].trend.temps.t4_c.. Quite a lot of unnecessary text/data taking space from the actual trend => Is there a way to access/interface the legend-data programmatically so I can change the presentation/naming?
Last updated: 2025-12-16

Post by gordonkeller360 on Escape character behavior for hex values in string -- what gives? ^{CODESYS Forge talk (Post)}
I have a program which sequentially places byte representations of characters from a string into an array. FUNCTION_BLOCK MoveBytesFromString VAR_IN_OUT abRxBuf: ARRAY [0..79] OF BYTE; END_VAR VAR testString : STRING := '$0A$R$L$TTesting,123...$94$86$0A'; iCount: DINT; END_VAR ---------------------------------------------------------------------------------------- // clear the buffer MEM.MemFill(ADR(abRxBuf), 80, 0); FOR iCount := 0 TO LEN(testString) - 1 DO // account for undesired null terminator of string abRxBuf[iCount] := testString[iCount]; END_FOR Escaped characters, like $T, $N, etc. work just fine, and so do their hex representation counterparts ($09, $0A, etc). However, when I put something like $94, I get a set of nonsense values... see image attached after one spin of the program. Could someone explain to me what is happening here? I'll continue to investigate...
Last updated: 2026-03-09

Post by manuknecht on Persistence Manager does not save alphabetically first value ^{CODESYS Forge talk (Post)}
I have several libraries which contain values that should be saved on a PLC. As apparently no Persistent Variable List is available within Libraries, I use the Persistence Manager to create a Persistence Channel in the Project which imports the library. I then specify the persistence channel in the library using the {attribute 'ac_persist':='PersistenceChannel_CT'} specifier. This generally works very well and gives me exactly the properties I require. However, it came to my attention that the (alphabetially) first value from the library is not saved in the created ASCII file. When checking the content of the Persistence Channel, it shows all the variables as defined in the library. But the created file does not contain the first value and it is not restored after restart or reset. (see attached picture) I disabled Periodic Saving and set xSaveOnChange to TRUE and so the file usually updates immediately after changing one of the values. When changing the first value, it does not update which is consistent with this value not being saved. I also created a sample project and library from scratch which shows the same issue both using a Raspberry Pi and using a Linux machine. Does someone know what the reason for this could be or did someone make similar experiences? Looking forward to hearing your suggestions. Thanks in advance and best wishes Manuel
Last updated: 2023-10-17

Post by abuckie on i2c master not running ^{CODESYS Forge talk (Post)}
Hello, I am trying to create an Ethernet/IP device that can read analog signals, do some basic logic on it and then hand communicate the results to an Ethernet/IP master. I am using the Raspberry Pi to experiment with this as I would ultimately like to drive a display as well. I have loaded up the runtime on the Pi and got the digital I/O working. I have an ADS1115 ADC to I2C board and I can't get it to work, I get a message telling me the i2c master is not running and I am not sure where to start with this. Is there a manual for running CODESYS on the Pi or something like that I am missing? I found this post and opening the project in CODESYS V3.5 SP21 it seems like tons of this wouldn't convert properly https://forge.codesys.com/forge/talk/Runtime/thread/f1400b71b6/ I have added in the library and device manually and copied the structured text program but lost at what to do if the core functionality of the master is not running. I appreciate any help, thanks.
Last updated: 2025-05-19

Post by farren on How to stay in a method until something is finished. ^{CODESYS Forge talk (Post)}
I know I'm thinking about this wrong -- too many decades of procedural and event-driven programming and only a few months of PLC ST programming...... I've created a visualization with a button that when pushed calls a method. I want the method to take a pressure reading, wait one minute and then take another pressure reading. I'm looking for leaks. I'm using TON for the delay. It seems like what is happening is that the method gets called once and it takes the first reading and starts the TON. But then execution continues, leaves that method call, and the second reading never happens. I can force the method to keep running until the whole thing is done with a While loop, but I understand that is considered BAD in PLC programming. If it push the button again to call the method again, it picks up where it left off and if the timer is complete then it runs the remaining code. How do I keep that method running until it is complete with just one call without using a while loop that ties up the PLC for a minute? Thanks! -Farren
Last updated: 2025-10-31

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