Post by esmith on OPTO22 Groov Epic PR2 Modbus Comms Dropping out every 2 hours and 4 Mins ^{CODESYS Forge talk (Post)}
I think I am having a similar issue. Have you found out what was causing this problem?
Last updated: 2024-09-10

Post by ben1 on How to write multiple coils (Modbus FC15) ^{CODESYS Forge talk (Post)}
Yeah that is odd - sometimes you have to do what you have to do unfortunately. Have you tried sending consecutive bits in the word instead - ie. instead of [0].0. [1].0, [2].0 etc, send [0].0,[0].1, [0].2 etc. ?
Last updated: 2024-11-17

Post by ph0010421 on Dynamically enabling/disabling Modbus slave devices in runtime (performance issue with timeouts) ^{CODESYS Forge talk (Post)}
Hello If you uncheck 'Auto restart Communication', it will try once and never again. You can manually reset the slave if needed : Slave.xReset (or something similar) Or I have a ModbusRTU library if you want to try it.
Last updated: 2025-08-12

Post by marekxc on Little endian to Float from Modbus RTU ^{CODESYS Forge talk (Post)}
Maybe try going back to step one and: Var Reg1: WORD; Reg2: WORD; Reg12: DWORD; Value: REAL; end_var // program Reg1:= 4096; Reg2:= 14884; Reg12:= (reg2 * 65536) + reg1; Value:= DWORD_TO_REAL(Reg12);
Last updated: 2023-12-28

Post by dim54 on MBChannel ^{CODESYS Forge talk (Post)}
Hello! I am interested in the Modbus Slave channel parameter uiReadLength to use in the ST-program (see picture). How to read the value of uiReadLength in a ST-program? Only Edwin the Great and Terrible can answer this question.
Last updated: 2024-01-22

Post by timvh on Timeout Error in Modbus Communication with WAGO PFC200 and iEM2050 Meter using 750-652 Module ^{CODESYS Forge talk (Post)}
I'm not sure, but maybe you have to configure the 750-652 first with the WAGO-IO-CHECK software to set it in RS485 mode?
Last updated: 2024-02-27

Post by dawidr on Timeout Error in Modbus Communication with WAGO PFC200 and iEM2050 Meter using 750-652 Module ^{CODESYS Forge talk (Post)}
Did you manage to solve the problem with time out? I got the same issue and I've no idea what I'm doing wrong.
Last updated: 2024-04-07

Post by dawidr on Timeout Error in Modbus Communication with WAGO PFC200 and iEM2050 Meter using 750-652 Module ^{CODESYS Forge talk (Post)}
Did you manage to solve the problem with time out? I got the same issue and I've no idea what I'm doing wrong.
Last updated: 2024-04-07

Post by marcolim on Slow modbus digital input response ^{CODESYS Forge talk (Post)}
Hi francoinf, I've the similar problem and similar configuration. I did with an Arduino Board loaded by a ModbusRTUServer application on it. What I've notice is the slowly acquisition when release the digital signal (e.g. pin2) when it gets off. Anyone have suggestion?! Thanks
Last updated: 2024-04-13

Post by marcolim on Slow modbus digital input response ^{CODESYS Forge talk (Post)}
[Update]. My issue's solved, I applied the resistors in Pull-down configuration on each digital input. In thus configuration never happened "floating or delaying" acquisition on SoftPLC/Arduino Board.
Last updated: 2024-04-15

Post by timvh on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
Most likely related to the Device Diagnostics functionality. Double click on your device (PLC), go to the tab "PLC settings". Enable the advanced option "Enable diagnosis for devices". Build your application again.
Last updated: 2024-04-15

Post by mbmik on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
Thanks alot for your time and help! I quickly tested the suggestion, as it makes a lot of sense. Unfortunately the erros still appear as before. The settings was already set before, and i tried turning it off.. no effect..
Last updated: 2024-04-16

Post by hyet on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
Currently seeing the same issue here, with a project moved from 3.5.19. Diving into it too to see if i can find the cause
Last updated: 2024-05-01

Post by guilhermeleao on How to communicate 2 pcs that are using CODESYS ^{CODESYS Forge talk (Post)}
I need to connect 2 computers on the same network that are running codesys, so that they can receive and change variable values from each other. This connection must preferably be made using Modbus.
Last updated: 2024-05-06

Post by zer0g on Modbus Client Request Not Processed ^{CODESYS Forge talk (Post)}
Hi, I have the same problem as the guys above. Any solution or hint in the right direction is appreciated. Codesys version 3.5.19.2, Lib version: 4.4.0.0. Thank you!
Last updated: 2024-05-29

Post by salvatorethomas on Port instantiation of serial interface in WAGO PLC using Modb_L05.lib in CoDeSys v2.3 ^{CODESYS Forge talk (Post)}
Hi — good description of the problem. A few suggestions / questions that might help narrow this down: Since your first serial port (COM2) works fine but the second (COM4 + MODBUS_EXT_MASTER) never opens, check whether the two ports are truly independent — some WAGO modules share internal resources, so COM4 might conflict with other functions or modules. Make sure that the physical wiring and module configuration for the second port (baud rate, flow control, RS-485 vs RS-422, etc.) exactly match what the library expects — a mismatch in flow control or wiring could prevent port opening even if the LED signals seem OK. Try using a plain SERIAL_INTERFACE on COM4 first (like you did for COM2) without Modbus logic — if that opens, you know the hardware + port config is fine, so the issue is more likely with modb_L05.lib. If the port opens but Modbus still fails, enable debug/logging (if available) to inspect whether the port opening fails or the subsequent Modbus negotiation fails. If you like — I can share a minimal example project I used with WAGO + COM4 + Modbus that worked; you could adapt that to test your setup. Wacky Flip
Last updated: 2025-12-01

Post by risele on Modbus connection via Qronox PCD3 M6893 ^{CODESYS Forge talk (Post)}
First, if you don't need to change conversion rules in runtime, take a look at "Unit conversion" module (Application -> add object -> UnitConversion). You can specify there biderectional conversion with different units, limits and so on. Second, since MODBUS don't have "real" types but only general 16-bit registers and Real is 32-bit, generally you need a byte-was conversion Real <> two Words. Note, that depending on the devices on both sides, there are two options: Real-> Word1, Word2 or Real-> Word2, Word1, where Word1 is minor register in Modbus register pair and Word2 is major. You can use simple union: TYPE u_Real : UNION rVal:REAL; wVal:ARRAY[0..1] OF WORD; dwVAL:DWORD; //same as previous, may be easier to specify the MB register END_UNION END_TYPE and convert it as following: VAR myUnion:u_Real; rValue_TO_SEND:REAL; rValue_TO_GET:REAL; END_VAR myUnion.rVal:=rValue_TO_SEND; rValue_TO_GET:=myUnion.rVal; Note, that WORD-order should be properly set in MODBUS registers, otherwise you will get strange values. This tool is helpful: https://www.scadacore.com/tools/programming-calculators/online-hex-converter/ Alternative, you can use functions as REAL_TO_DW and DW_TO_REAL from OSCAT_BASIC, for example.
Last updated: 2026-02-19

Post by janderson on OPC UA Server limitations, large array crashes runtime ^{CODESYS Forge talk (Post)}
when using an array of structs, the runtime crashes. but when using an array of LREALS, it'll do 100k at least
Last updated: 2023-08-23

Post by eschwellinger on How to configure CODESYSControl_User.cfg in order to use a specific network card for OPCUA Server ^{CODESYS Forge talk (Post)}
check this faq section here: https://faq.codesys.com/plugins/servlet/mobile?contentId=102137886#content/view/102137886
Last updated: 2023-08-25

Post by eschwellinger on How to configure CODESYSControl_User.cfg in order to use a specific network card for OPCUA Server ^{CODESYS Forge talk (Post)}
Hi Rossano, thank you for the feedback, you are right this need to be changed in the faq section. Regards Edwin
Last updated: 2023-08-28

Post by yr00 on OPC UA datasource low read frequency ^{CODESYS Forge talk (Post)}
Hello everyone, I am trying to test the OPC UA client feature in Codesys. My setup is the following; I have a Codesys simulation/ visualization running on Control Win V3. My OPC UA server is hosted on a Siemens 1518 PLC using PLCSim Advanced. The setup is completely virtual so there are no really PLCs. Everything is on my laptop. Writing data from the Codesys simualtion to the server is very quick. I have a PLC program running on another 1500 PLC which reads data from simulation via the server, and changes in the simulation (e.g. button pressed) appear within hundreds of miliseconds if not tens of miliseconds in my PLC program. However, when it comes to reading data from the OPC UA Server by Codesys, it taks around 1-2s. I connected a UAExpert client and it gets update very quickly so I am fairly sure the problem is with Codesys. I have tried changing the update rate in datasource -> General and Diagnosis, but it doesn't seem to have an effect. Do you guys have any suggestion on what I can do?
Last updated: 2023-08-29

Post by janber0206 on RPI is license server down ^{CODESYS Forge talk (Post)}
I had the same problem. Problem solved: all licences purchased before October 2022 must be updated by Codesys. To do so, simply contact the support in the Codesys Store.
Last updated: 2023-10-30

Post by nizrahel on OpC UA server on Raspberry Pi 64 SL runtime ^{CODESYS Forge talk (Post)}
Hi all! I'm working on an home project using a Raspberry Pi 3 device with Codesys for Raspberry Pi 64 SL runtime. I would like to create the HMI interface with Siemens WinCC Unified (or Advanced) configuring the Raspberry as OPC UA server. I tryed everything, but I didn't find the way to let the OPC UA connection works using UaExpert. I tryed to use anonymous connection, authenticated connection and the ip address instead of the server name in the path connection. There is no way to connect to the OPC UA server and I was asking myself if this feature is really supported for the runtime version used. Another strange thing I noted, is that is not possible to quickly create an OPC UA certificate in the Security Screen, as show in any tutorials. I have correctly created the Symbol Configuration enabling the OPC UA feature. I attach to this topic some printscreen of the actual configuration (sorry for the italian language interface, but I didn't find the way to switch to english). Thank you very much in advance for your support and advices!
Last updated: 2023-12-03

Post by eschwellinger on OPCUA Ctrl-Node fehlt ^{CODESYS Forge talk (Post)}
..dann mal im WBM alles deaktivieren, da der OPC UA Server ja direkt im PFC200 SL RUntime integriert ist und nicht über die WBM Oberfläche zu konfigurieren ist.
Last updated: 2023-12-05

Post by shabroz-gill on Data Sources Manager causing exception due to float or double type in OPC server ^{CODESYS Forge talk (Post)}
Was this ever resolved? I see the same issue with the version 3.5.19.5
Last updated: 2024-07-01

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