Post by totorovic on Hard shutdown: no code on device after power on ^{CODESYS Forge talk (Post)}
However, if faulty EtherCAT cables were the issue, why wouldn't the error occur during normal operation? Why would bad cables only cause problems during a hard shutdown? I don't have the answer to this question. One last question: When you encountered this behavior, did you see a similar error in your logs? i.e, an "AccessViolation" exception in the EtherCAT Task Yes. It was the exeption you can see in attached file.
Last updated: 2024-10-03

Post by sturmghost on Find visualization elements that require a lot of computing time ^{CODESYS Forge talk (Post)}
I found out that the Codesys simulation mode is not good to measure performance. As soon as I upload the code onto the hardware PLC I can see that my visu-task needs around 60 ms to complete. I'm wondering if there is a possibility to find out which visualization/visualization element takes a lot of computing time? Then I would look for ways to decrease the long computing time.
Last updated: 2024-01-22

Post by yofi on Raspberry Pi 4 POU not running ^{CODESYS Forge talk (Post)}
I have this error where the pou doesn't run even for simple programs like contact and a coil if i remove the pou from the task and put another one it works for one run then it stops working again in the photo we can see a contact is on but the coil connected to it is still not on and the device is in run mode I had this issue again and again any help
Last updated: 2024-06-02

Post by yofi on Raspberry Pi 4 POU not running ^{CODESYS Forge talk (Post)}
I have this error where the pou doesn't run even for simple programs like contact and a coil if i remove the pou from the task and put another one it works for one run then it stops working again in the photo we can see a contact is on but the coil connected to it is still not on and the device is in run mode I had this issue again and again any help
Last updated: 2024-06-02

Post by swe-hob on call of a method of a function block in another program ^{CODESYS Forge talk (Post)}
Hi, Let's assume following: PRG_1 fb_1 : fbExample1; fb_1.method_1 do something... PRG_2 fb_2 : fbExample2; fb_2.method_2 if xTest then PRG_1.fb_1.method_1(); end_if; Is there a reason why runtime hangs when I call the method_1 in PRG_1 from a method in PRG_2? Both programs run in the same task. No chance that any other program calls the method. What I practically do there is that in the program PRG_2 I add a structed object into a buffer. In PRG_1 I just process the items in the buffer.
Last updated: 2024-06-03

Post by swe-hob on call of a method of a function block in another program ^{CODESYS Forge talk (Post)}
Hi, Let's assume following: PRG_1 fb_1 : fbExample1; fb_1.method_1 do something... PRG_2 fb_2 : fbExample2; fb_2.method_2 if xTest then PRG_1.fb_1.method_1(); end_if; Is there a reason why runtime hangs when I call the method_1 in PRG_1 from a method in PRG_2? Both programs run in the same task. No chance that any other program calls the method. What I practically do there is that in the program PRG_2 I add a structed object into a buffer. In PRG_1 I just process the items in the buffer.
Last updated: 2024-06-03

Post by ben1 on How to stay in a method until something is finished. ^{CODESYS Forge talk (Post)}
Why must you use a method? Top of my head can't you just use the button to turn on a bit and use it in a normal task? Just turn a bit on with the button, and run a TON from it in code, and turn it back off with the ton. And then just log the pressure on both the rising & falling edge?
Last updated: 2025-11-03

Post by sheberle on ERROR: Calling the program "AlarmStorage_Prg" is not allowed from multiple tasks ^{CODESYS Forge talk (Post)}
Do you have any additional information about when the error occurs? I am trying to recreate this issue to find a workaround... Maybe you could also make the project available. You could add the following logfilter to the CODESYS configuration file: [CmpLog] Logger.0.Filter=0xFFFFFFFF Logger.0.Enable=1 Logger.0.MaxEntries=10000 Logger.0.MaxFileSize=1000000 SysSem.Filter=0xFFFFFFFF SysTask.Filter=0xFFFFFFFF I hope that the log filter will show us which task is responsible for this, so we can narrow it down a bit more.
Last updated: 2026-03-31

Post by jegerjon on Testing of Codesys program ^{CODESYS Forge talk (Post)}
I have a simulation function that toggle xSimActive. I map all IO variables to "IO GVLs" when xSimActive=0. I map IO corresponding SimIO GVL to "IO GVLs" when xSimActive=1. Then I write code for the simulation program that runs when xSimActive=1. Typically increase flow corresponding to pump speed, simulate tankfilling corresponding to flow and so on. I made a FC that require a correct code to activate simulation to avoid unintended activation by service dept. When comissioned remove any possibility to activate simulation. Super when officetesting and supporting service dept. + cheap as it requires no additional equipment, and it is easier to support customer later on in the life cycle as you can test proposed changes without setting up a testlab.
Last updated: 2023-12-07

Post by jegerjon on Testing of Codesys program ^{CODESYS Forge talk (Post)}
I have a simulation function that toggle xSimActive. I map all IO variables to "IO GVLs" when xSimActive=0. I map IO corresponding SimIO GVL to "IO GVLs" when xSimActive=1. Then I write code for the simulation program that runs when xSimActive=1. Typically increase flow corresponding to pump speed, simulate tankfilling corresponding to flow and so on. I made a FC that require a correct code to activate simulation to avoid unintended activation by service dept. When comissioned remove any possibility to activate simulation. Super when officetesting and supporting service dept. + cheap as it requires no additional equipment, and it is easier to support customer later on in the life cycle as you can test proposed changes without setting up a testlab.
Last updated: 2023-12-07

Post by mikek10 on HTTP Client TCP Init Error ^{CODESYS Forge talk (Post)}
Hi, I tried posting in the discussion for the HTTP Client example but perhaps that is not monitored? I have been using http client successfully for approximately 12 months, however in recent weeks I have begun to get TCP_INIT_ERROR when attempting to communicate. The only resolution seems to be power cycling and then the connection begins to work again for a time. I am not aware of any changes to code or libraries between working ok and now. Cold reset does not resolve, only power cycle. It seems the error from NBS.TCP_Client is 6002 which I think is invalid_addr However the address is the same when working and not working?
Last updated: 2024-07-04

Post by rcanfield on Code Coverage and Test Manager ^{CODESYS Forge talk (Post)}
I am exploring the possibility of measuring test coverage using the Test Manager and Profiler tools. It appears there are some significant limitations. Has anyone been successful trying to use these tools? Here are my observed limitations. Am I misunderstanding anything? * Profiler only works for one "run cycle". Even warm resets will clear the coverage calculations. Thus, all tests would have to manually reset values when complete to prevent contamination to other tests. * It is not possible to see which statements were/weren't executed. One would have to use the flow control tool which cannot be used in conjunction with the Profiler, and must be viewed in realtime. * The profiler control cannot be automated and therefore must be executed through a manual procedure. Thank you!
Last updated: 2024-07-11

Post by rcanfield on Code Coverage and Test Manager ^{CODESYS Forge talk (Post)}
I am exploring the possibility of measuring test coverage using the Test Manager and Profiler tools. It appears there are some significant limitations. Has anyone been successful trying to use these tools? Here are my observed limitations. Am I misunderstanding anything? * Profiler only works for one "run cycle". Even warm resets will clear the coverage calculations. Thus, all tests would have to manually reset values when complete to prevent contamination to other tests. * It is not possible to see which statements were/weren't executed. One would have to use the flow control tool which cannot be used in conjunction with the Profiler, and must be viewed in realtime. * The profiler control cannot be automated and therefore must be executed through a manual procedure. Thank you!
Last updated: 2024-07-11

Post by madskaizer on ModbusTCP Slave Device, maximum uiClientConnections? ^{CODESYS Forge talk (Post)}
I got a Wago PFC200V2, running Codesys 3.5.16.40, 100ms scan cycle, consumes about 20ms. It will randomly crash the runtime every 10 minutes to a few hours. We suspect an overloaded ModbusTCP Slave Device, as this is work done by a 3rd party contractor, but we can not find anything in the help files or documentation, that mentions a hard limit on maximum number of clients connections. This PLC currently has 44 client connections to the Slave Device and 29 slaves configured for its own Master Device. This topic metnions a hard limit of maximum 16 connections, but where is this written? https://forge.codesys.com/forge/talk/Engineering/thread/bd95b9d6d2/
Last updated: 2025-03-26

Post by pernockham on AC Persistence - values are not read from file during start? ^{CODESYS Forge talk (Post)}
I swear I tested this like 20 times yesterday without success. Repeated it today and it works. Maybe the system needed a "real" power reboot? To note. To make a manual edit of a variable I tried some different approaches this is what worked for me. "system/online edited" gvl_var.example_variable REAL:F16#2FFB334H-4 767.7 "manually edited" (with runtime stopped followed by a "cold start" to read from file) gvl_var.example_variable REAL:790.1 (the system will use the manual value but will not set an equivalent "hex" value until next online edit/write cycle)
Last updated: 2025-09-03

Post by cedriclee on RaspberryPI reconnection error ^{CODESYS Forge talk (Post)}
"Hello, I'm Cedric Lee, a PLC engineer based in Korea. I'm reaching out about an ongoing issue with the connection when attempting to control Beckhoff modules using Raspberry Pi with CODESYS for the first time. I use CODESYS to target the Raspberry Pi's IP, install version 4.10.0.0 of the CODESYS Runtime Package, and upon pressing Start in the Runtime, the target connects to the Raspberry Pi. However, within about a minute, an error window appears, stating 'no connection to the device. please rescan your network,' leading to the disconnection of the target. This cycle repeats. I've attached some pictures for your reference. I'm using CODESYS Development System V3, Raspberry Pi 4 Model B (installed as 64-bit), and Beckhoff EK1100 modules. If anyone has a solution to this issue, please help. Your assistance is greatly appreciated."
Last updated: 2024-01-11

Post by alexgooi on Update boot project default unchecked ^{CODESYS Forge talk (Post)}
Dear Forum, I'm currently switching to Codesys V3.5 SP19. When I want to do an online change, I get the option to update the boot project, in other (codesys based) packages this is checked on by default. In Codesys V3.5 SP19 (and maybe older versions) this is unchecked by default. We are doing a lot of remote updates with systems that almost never power cycle. In other words when this box is forgotten the system will run fine until a blackout. Is it possible to get it checked on by default? This question was asked before, but no answers where given. https://forge.codesys.com/forge/talk/Engineering/thread/ffb4ffa298/ Thank you in advance.
Last updated: 2024-02-09

Post by alessandro on SysMemCmp SysMemCpy ^{CODESYS Forge talk (Post)}
VAR Data1:ARRAY[1..10] OF SINT ; Data2:ARRAY[1..10] OF SINT ; Data3:ARRAY[1..10] OF SINT ; Data4:ARRAY[1..10] OF SINT ; ex_1 : BOOL ; ex_2 : BOOL ; enable : BOOL :=0 ; END_VAR // PROGRAM // The scope of this example is compare and copy the values of two ARRAY only if some value is different using SysMemCmp and SysMemCpy. // In this 2 example we don't use a FOR cicle for do this, and pBuffer1 and pBuffer2 is just a pointer to ARRAY. See details in Library util.SysMem of Codesys // The compare funcion util.SysMem.SysMemCmp is bidirectional if Data1 chanege respect Data2 ex_1 go to 1 and if Data2 change respect Data1 also // but the copy function util.SysMem.SysMemCpy work only from source ARRAY pSrc:=ADR(Data1) to destination ARRAY pDest:=ADR(Data2) // Example 1 Full ARRAY compare and copy // This compare 2 different equal ARRAY and if there is some difference ex_1 go to 1 and if you give enable he copy Data1 in Data2 ex_1 := TO_BOOL(util.SysMem.SysMemCmp(pBuffer1:=ADR(Data1), pBuffer2:=ADR(Data2), udiCount:=SIZEOF(Data1))); IF ex_1 AND enable THEN util.SysMem.SysMemCpy(pDest:=ADR(Data2), pSrc:=ADR(Data1), udiCount:=SIZEOF(Data1)); END_IF // Example 2 Only selected area of the ARRAY compare and copy // This compare 2 different equal ARRAY starting from position number [3] for 4 byte in this case start at position [3] and finish at position number [6] // and if there is some difference only in area [3..6] of the ARRAY ex_2 go to 1 if you give enalbe he copy Data3[3..6] in Data4[3..6] // if something change in other array position[0..2] or [7..10] are ingnored ex_2 := TO_BOOL(util.SysMem.SysMemCmp(pBuffer1:=ADR(Data3[3]), pBuffer2:=ADR(Data4[3]), udiCount:=4)); IF ex_2 AND enable THEN util.SysMem.SysMemCpy(pDest:=ADR(Data4[3]), pSrc:=ADR(Data3[3]), udiCount:=4); END_IF // Attention udiCount input is intended in <byte> in the example 1 I pass to udiCount:=SIZEOF(Data1) for compare and copy the intere ARRAY and // SIZEOF pass the size of intere ARRAY in byte to the function input, in this 2 examples I used variable type SINT each one occupie 1 byte and one position in the ARRAY // and in the example 2 I pass udiCount:=4 for compare and copy only 4 position of Data3/4[3..6] if you want to extend this example and use it for an ARRAY OF WORD // remember that each WORD will occupe 2 byte (16 bit) and you will have to pass udiCount:=SIZEOF(Data1) if you need to compare intere ARRAY example 1 // but need udiCount:=(42) for the example 2 because need to compare and copy 4 word each occupie 2 byte (16 bit). // For REAL (32 bit) need udiCount:=SIZEOF(44) for LREAL or (64 bit) need udiCount:=SIZEOF(416) // a good rule is calculate the dimension of the ARRAY in byte without empty space at the end, multiple of data type number for variable bigger then 8 bit // Example : If you want to create an ARRAY for 5 REAL (32 bit) each occupie 4 byte the correct size is ARRAY[0..19] OF REAL 54=20 position. // NOTE : In the example the position of compare function util.SysMem.SysMemCmp is first and the copy function util.SysMem.SysMemCpy inside the IF is after // in one cycle of the program the two array is compared and if there is some difference and enable are copied. // If you move util.SysMem.SysMemCmp after the IF cycle he will copare the ARRAY in the current cycle but the copy of the value will do in the next cycle.</byte>
Last updated: 2025-10-24

Post by markusef3 on Verhalten bei zu kurz gesetzter Task-Zyklus-Zeit ^{CODESYS Forge talk (Post)}
Hallo zusammen, ich habe eine Frage bezüglich dem Verhalten der Tasks. In der Hilfe und hier im Forum sowei im Internet konnte ich diesbezüglich leider nichts finden. Wie genau verhält sich Codesys wenn mehrere zyklische Task eingestellt sind und bei einem ab und zu die Abarbeitung des angehängten Programmes länger dauert als das Aufrufintervall eingestellt ist. D.H. der nächste Aufruf würde "theoretisch" erfolgen bevor alles im Program abgearbeitet ist. Z.B. Intervall ist 1ms, Abarbeitung dauert manchmel 1,1ms oder länger. (Watchdog ist zwar eingeschaltet, aber größer gewählt als das Zyklische Intervall zum Aufruf. Watchdog soll jetzt auch nicht das Thema sein). Was passiert in so einem Fall? - Wird das Programm zuerst zu Ende abgearbeitet und dann der nächste Aufruf gestartet? - Wird das Programm "mittendrin" unterbrochen und dann neu gestartet? - wie genau muss ich mir das vorstellen wenn dem so ist? - ...... - ...... Ich konnte überall nur Anleitungen finden wie die Tasks zu konfigurieren sind, jedoch nichts dazu was im oben genannten Fall genau passieren wird. Gruss Markus
Last updated: 2023-10-19

Post by amani on PN Controller auf Raspberry Pi 4 ^{CODESYS Forge talk (Post)}
Hallo zusammen, Ich mache +/- erste Schritte mit RaspberryPi und Codesys: tolle Sache! Ich habe Codesys V3.5 auf einem Raspberry Pi 4 am laufen. Ich würde damit gerne einen Profinet-Slave bedienen. Die Kommunikation läuft, nun habe ich das Problem dass ich nicht verstehe wie ich den PN-Task mit dem PLC task synchron halte: Ich muss dem Slave eine Parameter-ID übergeben und beim nächsten Zyklus die Antwort auslesen. Da es dann mehrere Parameter gibt die ich nur sequentiell auslesen kann benutze ich also einen Zähler der mir die ID's durchstept. Aktuell sieht es aus als ob dieser Zähler schneller inkrementiert als der Slave antwortet (ich habe z.Bsp. 5 Parameter, diese zeigen dann alle das gleiche oder springen zwischen den Parametern). Also kurz gesagt ich muss sicherstellen dass die Datenbytes vom Slave zur gesetzten Parameter-ID passen... Ich wäre froh um ein paar Tipps! Herzlichen Dank! Grüsse, Stephan A. Wicki
Last updated: 2025-02-26

Post by timl on BacNet "Unaufgelöste Referenz" ^{CODESYS Forge talk (Post)}
Hallo, ich habe Probleme beim nachbauen des BacNet2 Tutorials "Erste Schritte" aus der CODESYS Online Help. https://content.helpme-codesys.com/de/CODESYS%20BACnet/_bacnet_first_steps.html Das Anlegen des BacNet2 Servers und der danach folgenden BacNet Datenpunkte erfolgt ohne Probleme. Der Code lässt sich mit F11 auch Fehlerfrei generieren. Beim Download auf die SPS tritt dann der Fehler auf dem Bild auf. Anbei auch ein Bild des Logs nach dem Download. CODESYS BACnet 2.0.0.0 ist über den Installer runtergeladen. Device: CODESYS Control Win V3 x64 Version 3.5.19.40 CODESYS 3.5.19.40 Im Bibliotheksverwalter ist BACnet2 2.0.0.0 aufgeführt Die Konfigurationsdatei habe ich mit folgenden anpassungen abgespeichert: [ComponentManager] Component.1=CmpTargetVisuStub Component.2=CmpWebServer Component.3=CmpWebServerHandlerV3 Component.4=SysCpuMultiCore Component.5=SysReadWriteLock Component.6=SysCpuBreakpoints Component.7=SysPipeWindows ;Component.8=CmpHilscherCIFX ;Component.9=CmpPCANBasicDrv ;Component.10=CmpCANFoxDrv ;Component.11=CmpIxxatCANDrv ;Component.12=CmpBlkDrvCanServer ;Component.13=CmpBACnet Component.14=CmpBACnet2 [CmpBACnet2] ;configuration file of the BACnet stack IniFile=$PlcLogic$/bacstac2.ini ;task priority of the BACstack process task, default: TASKPRIO_NORMAL_END (159) TaskPrio=128 ;name of the named pipe for the communication with the BACstack AppName=/tmp/BACnetServer Habe ich etwas vergessen?
Last updated: 2024-02-16

Post by caprez95 on Trace Restart Visuelement ^{CODESYS Forge talk (Post)}
Hallo zusammen. Ich habe schon länger mit dem Problem zu kämpfen, dass ich einen Trend (Visuelement) nicht resetten (neustarten) kann. Ich habe es jetzt mit dem Beispiel hinbekommen, die Trace-Aufzeichnung über die CmpTraceMgr Bibliothek zu steuern. Aber wie bekomme ich diese Trace-Aufzeichnung in ein Visuelement? Der Code sieht wie folgt aus: // Configure trace IF xInit THEN // Create a trace packet PacketConfig.pszName := ADR('IECTraceConfiguration.Trace1'); // Name of trace PacketConfig.pszApplicationName := ADR('IECTraceConfiguration'); // Name of the application PacketConfig.pszIecTaskName := ADR('Task'); // Name of the task PacketConfig.pszComment := ADR('Demo packet'); PacketConfig.ulEveryNCycles := 1; PacketConfig.ulBufferEntries := 1000; PacketConfig.ulFlags := TRACE_PACKET_FLAGS.TRACE_PACKET_FLAGS_TIMESTAMP_MS AND TRACE_PACKET_FLAGS.TRACE_PACKET_FLAGS_AUTOSTART; IF (NOT fbTraceManager.CreatePacket(PacketConfig := PacketConfig, hPacket=>hPacket1)) THEN xError := TRUE; END_IF // Create a trace record RecordConfig.pszVariable := ADR('iSignal'); // This is the name of variable to record RecordConfig.tcClass := INT_TO_UDINT(TypeClass.TYPE_INT); // Type of the recording variable RecordConfig.ulSize := SIZEOF(iSignal); // Size of the recording variable pApp := AppFindApplicationByName('IECTraceConfiguration', 0); AppGetAreaOffsetByAddress(pApp, ADR(iSignal), ADR(RecordConfig.tvaAddress.taAddress.Area.usArea), ADR(RecordConfig.tvaAddress.taAddress.Area.ulOffset)); // Get and set area offsets RecordConfig.tvaAddress.ulAddressFlags := TRACE_VAR_ADDRESS_FLAGS_IEC OR TRACE_VAR_ADDRESS_FLAGS_AREA_OFFSET; RecordConfig.ulGraphColor := 16#FF00FF00; // green RecordConfig.ulGraphType := 1; // Line with points IF (NOT fbTraceManager.AddRecord(RecordConfig := RecordConfig, hPacket := hPacket1, hRecord => hRecord1)) THEN xError := TRUE; END_IF xInit := FALSE; END_IF // Starts the recording IF xStart THEN IF (NOT fbTraceManager.StartPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xStart := FALSE; END_IF // Stop the recording IF xStop THEN IF (NOT fbTraceManager.StopPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xStop := FALSE; END_IF // Reset the recording IF xReset THEN IF (NOT fbTraceManager.ResetPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xReset := FALSE; END_IF
Last updated: 2024-06-04

Post by caprez95 on Trace Restart Visuelement ^{CODESYS Forge talk (Post)}
Hello everyone. I've been struggling with the problem for a long time that I can't reset (restart) a trend (visual element). With the example I have now managed to control the trace recording via the CmpTraceMgr library. But how do I get this trace recording into a visual element? The code looks like this: // Configure trace IF xInit THEN // Create a trace packet PacketConfig.pszName := ADR('IECTraceConfiguration.Trace1'); // Name of trace PacketConfig.pszApplicationName := ADR('IECTraceConfiguration'); // Name of the application PacketConfig.pszIecTaskName := ADR('Task'); // Name of the task PacketConfig.pszComment := ADR('Demo packet'); PacketConfig.ulEveryNCycles := 1; PacketConfig.ulBufferEntries := 1000; PacketConfig.ulFlags := TRACE_PACKET_FLAGS.TRACE_PACKET_FLAGS_TIMESTAMP_MS AND TRACE_PACKET_FLAGS.TRACE_PACKET_FLAGS_AUTOSTART; IF (NOT fbTraceManager.CreatePacket(PacketConfig := PacketConfig, hPacket=>hPacket1)) THEN xError := TRUE; END_IF // Create a trace record RecordConfig.pszVariable := ADR('iSignal'); // This is the name of variable to record RecordConfig.tcClass := INT_TO_UDINT(TypeClass.TYPE_INT); // Type of the recording variable RecordConfig.ulSize := SIZEOF(iSignal); // Size of the recording variable pApp := AppFindApplicationByName('IECTraceConfiguration', 0); AppGetAreaOffsetByAddress(pApp, ADR(iSignal), ADR(RecordConfig.tvaAddress.taAddress.Area.usArea), ADR(RecordConfig.tvaAddress.taAddress.Area.ulOffset)); // Get and set area offsets RecordConfig.tvaAddress.ulAddressFlags := TRACE_VAR_ADDRESS_FLAGS_IEC OR TRACE_VAR_ADDRESS_FLAGS_AREA_OFFSET; RecordConfig.ulGraphColor := 16#FF00FF00; // green RecordConfig.ulGraphType := 1; // Line with points IF (NOT fbTraceManager.AddRecord(RecordConfig := RecordConfig, hPacket := hPacket1, hRecord => hRecord1)) THEN xError := TRUE; END_IF xInit := FALSE; END_IF // Starts the recording IF xStart THEN IF (NOT fbTraceManager.StartPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xStart := FALSE; END_IF // Stop the recording IF xStop THEN IF (NOT fbTraceManager.StopPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xStop := FALSE; END_IF // Reset the recording IF xReset THEN IF (NOT fbTraceManager.ResetPacket(hPacket := hPacket1)) THEN xError := TRUE; END_IF xReset := FALSE; END_IF
Last updated: 2024-06-04

Post by dnordenberg on BOOL variable in OPC UA and modbus simultaneously ^{CODESYS Forge talk (Post)}
How can I have an BOOL variable that is read/write in both modbus TCP server and from OPC UA at the same time? Variables with %MX.n %QX.n addressing which is used for BOOL/coils in modbus server is not allowed in OPC UA symbol list on Schneider M251 controllers. I have already asked on Schneiders forum but there are not a lot of codesys experts over there :( So OPC symbols can't have a address and the modbus TCP server needs a address. So how should I do it then? It seems like an impossible combination. Since I want read/write access from both ways I can't just simply make a second variable and assign it the value of another since it would be a one way assignment. I also tried using VAR_CONFIG which then makes the address syntax %Q or %M in my main variable list and that fools OPC UA Symbol Configuration to allow it and then I add the complete %MX.n address of it in the VAR_CONFIG list. This semi works, I can toggle the BOOL from modbus but the OPC UA symbol seems to be read only. It displays symbol status but nothing happens when I toogle it. I think I need another way to have the variables and symbols pointing to the same bits in memory... My plan B is to write a BOOL array compare FB that saves a history bit from previous cycle and if that does not match current status at next cycle for either the OPC symbol or the modbus variable then it copies the new status over to the other. Maybe ugly but it's like my last alternative. Kind regards David
Last updated: 2025-07-14

Post by duvanmoreno24 on Modbus writing on value change ^{CODESYS Forge talk (Post)}
Hi all, I want to know if someone has an idea of how I can write on value change in Modbus Codesys. I have a Wago PLC and I was used to work with E-cockpit which it was quite easy to do that without the necessity to trigger any value when there was a change in the variable ( I will put how easy is ). how you can see just changing the trigger in "On value Change" will do that channel writing automatically when It detects a change in those arrays. On the other hand, in Codesys if I enable the rising edge in Codesys It ask me to put a bool variable and if triggers is going to write that value. That is making me that I have to create a function or a logic to detect the change, the problem I have is that doing that is very tedious. I first approach I got it was to create a Function who returns a bool when the value change, but I tried to keep the old value but what is happening is that in Functions all the data is erased every cycle so I can not keep any Old value. so in the Main program the trigger is going to be TRUE all the time due, the old value is cero every cycle. The second approach I got it was using a function Block (POU_1) and it works but I dont want to instance that function for every Channel or value that I want to check if the value change, Basically if I have 200 values to write trhough modbus I have to create 200 instances of that function which I think it is not practicall at all. It should be a better way to implement this as e-Cockpit from Wago Does. However, I haven't been able to know how.
Last updated: 2024-03-26

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