Post by dawidr on Timeout Error in Modbus Communication with WAGO PFC200 and iEM2050 Meter using 750-652 Module ^{CODESYS Forge talk (Post)}
Last updated: 2024-04-07

Post by csanderson on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
I am also having this same issue after upgrading to 3.5.20.0. Any help Codesys?
Last updated: 2024-04-17

Post by santana on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
I'm having this same issue. I upgraded to 3.5.20.0 from 3.5.19.20. Now I have the precompile errors shown above.
Last updated: 2024-04-17

Post by eschwellinger on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
error need to be solved by CODESYS. hopefully next release
Last updated: 2024-05-01

Post by zer0g on Modbus Client Request Not Processed ^{CODESYS Forge talk (Post)}
Hi, Thank you for your suggestion but the problem is fixed after I disabled and enabled the network adapter from Windows settings.
Last updated: 2024-05-30

Post by eschwellinger on Modbus TLS Kommunikation ^{CODESYS Forge talk (Post)}
hi, das geht leider nicht mit aktivierter Verschlüsselung , sorry - denke aktuell bleibt dir nur auf Slave Seite die Verschlüsselung zu deaktivieren.
Last updated: 2025-11-09

Post by dafalin-codesys on Transparent wireless serial bridge for Modbus RTU – experience with LoRa/WiFi RS-485 link to CODESYS runtime ^{CODESYS Forge talk (Post)}
Last updated: 2026-03-18

Post by nehaltrivedi96 on Modbus connection via Qronox PCD3 M6893 ^{CODESYS Forge talk (Post)}
Thank you for your suggestions, based on it I will modify the code
Last updated: 2026-02-18

Post by danp1406 on Question about Demo License limitations for Modbus TCP communication and Fieldbus Instances ^{CODESYS Forge talk (Post)}
Hello everyone, I am currently working with CODESYS Virtual Control for Linux running in Docker on a Debian virtual machine. I am deploying my application using Deploy Control SL, and in my project I am using the ModbusFB library to implement Modbus TCP communication. My setup is the following: I am trying to establish a Modbus TCP connection between a virtual PLC (CODESYS acting as Modbus TCP Client/Master) and a Siemens S7-1200 PLC acting as a Modbus TCP Server. From the Debian VM, I can successfully ping the S7-1200 and verify that port 502 is open using tools like nc. Network-wise, everything appears to be correct. However, when running the application in CODESYS, I receive messages such as “Demo mode for Modbus/TCP Master started. Will expire and stop!” and socket errors like “ClientSocket.UpdateStatus socket error 111 disconnecting.” The ClientTCP block from the ModbusFB library attempts to connect, but the connection does not remain stable. My main question is whether the CODESYS demo license explicitly limits or interrupts Modbus TCP Master communication. Is it expected that in demo mode the runtime will automatically close sockets after some time or prevent stable Modbus TCP connections? I would like to confirm whether this behavior is normal when using ModbusFB in demo mode, or if I should continue troubleshooting the configuration. Additionally, I would like clarification regarding the “fieldbus instances” mentioned in CODESYS licensing options (for example, 2, 4, or 16 instances). What exactly is considered one fieldbus instance? Does one Modbus TCP Client block count as one instance? Does each active connection to a different device count separately? Do Modbus TCP Master and Server count independently toward the total number of instances? Finally, I would appreciate clarification on any other practical limitations of demo mode when using industrial communication libraries such as ModbusFB. Are there limits on the number of connections, number of requests, or communication duration? I am trying to determine whether demo mode is sufficient for testing a virtual PLC communicating with a Siemens S7-1200 over Modbus TCP, or whether a full license is required even for this kind of validation scenario. Thank you in advance for any guidance.
Last updated: 2026-02-25

Post by ahuckphin on Issues with Modbus Slave with Raspberry Pi ^{CODESYS Forge talk (Post)}
codesyscontrol_user.cfg [SysCom] Linux.Devicefile.1 = /dev/ttyUSB0 portnum:=COM.SysCom.SYS_COMPORT1; **parameters are used in the python-script ** method: "rtu" port: "COM8" baudrate: 9600 stopbits: 1 bytesize: 8 parity: 'N' timeout: 1 register address for humidity: 0x000 register address for temperature: 0x001 unit ID: 1 **parameteized in the modbus-master-comport ** see attached files
Last updated: 2024-07-11

Post by nltheves on Raspberry PI4 Serial Port ^{CODESYS Forge talk (Post)}
Hi Ricardo. I was having the same problem with Codesys and a Raspberry Pi 2W while using the GPIO uart. Your post helped me a lot. Thanks! But could not understand why MODBUS parity bit makes Codesys MODBUS COM driver stopping to work after first request transmission. Did you see this @eschwellinger ? Regards, Nelson
Last updated: 2024-07-18

Post by oymyakon on Modbus Lockup ^{CODESYS Forge talk (Post)}
Hi i have a project where i am communicating with many modbus devices using TCP to serial. This is all working extremely well except when i turn one of the remote devices off. If i leave the auto reconnect on it still doesn't talk to the rmianing devices and if i turn Auto reconnect off it locks up. Any help would be appreciated. Paul.
Last updated: 2024-08-07

Post by oymyakon on Modbus Lockup ^{CODESYS Forge talk (Post)}
Hi i have a project where i am communicating with many modbus devices using TCP to serial. This is all working extremely well except when i turn one of the remote devices off. If i leave the auto reconnect on it still doesn't talk to the rmianing devices and if i turn Auto reconnect off it locks up. Any help would be appreciated. Paul.
Last updated: 2024-08-07

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 sking on ModbusTCP/slave ^{CODESYS Forge talk (Post)}
i can not find the solution, i have 2 modbus tcp slave and i want to know how to do when one is activated the other one is desactivated. that means when i run the project, with a bouton click on my web visu i can choose wich modbus slave i want to activate. can someone have a solution plz ? thank you :)
Last updated: 2025-04-01

Post by sandro66 on Application-based license Modbus Channels ^{CODESYS Forge talk (Post)}
Hi, I imported an old project created with version 3.51.20.50 into the new version 3.51.21.20. I'm using ModbusFB.ClientTCP v4.5.0.0. Strangely, I can no longer download the project due to a licensing issue I didn't have before. The number of Modbus channels has gone from 1 to 54!, and there's no license that would work. Can anyone tell me where I'm going wrong? Thanks Sandro
Last updated: 2025-08-27

Post by nano on Modbus TCP/IP slave communication errow ^{CODESYS Forge talk (Post)}
please tell us the exact error message from diagnostic. U can view it at devicetree in the node-element diagnostic from modbus-configuration. u also can activate the function auto-reconnect in master and increase a little bit the timeout and the repetition to male thw communication a little bit more robust
Last updated: 2024-02-04

Post by nulltrace on Modbus TCP Server connection is ESTABLISHED but all holding registers are value 0? ^{CODESYS Forge talk (Post)}
your case looks different, the first one was an codesys modbus tcp-slave, your's an Master-Application with gateway. I dont know this Unit, but i would say, from Point of Codesys it looks wrong configured. Just give us more detailed configuration and the please make a sketch of the topology you're trying to realise.
Last updated: 1 day ago

Post by squiggleypuff on Can't Add New Version of Modbus TCP Master ^{CODESYS Forge talk (Post)}
I'm having a tough time trying to get Modbus working on a Festo CPX-E PLC; it throws these pre-compiler errors as soon as I add in my Modbus TCP Master 3.5.12.30 to my project: I'm confused about the C0046 error, as I have IODrvModbusTCP 4.3.0.0 Library installed. So I thought maybe I needed to use the newest Modbus TCP Master 4.3.0.0, which is in my device repository: However, whenever I go to add this underneath the Ethernet adapter (which is version 4.2.0.0), the only TCP Master version available is the old 3.5.12.30 one, even if I have Display all versions checked.: I even went so far as to delete the old version, but then there were no options to add a Modbus TCP Master under my Ethernet adapter. What needs to be done to use the newest Modbus TCP Master? Or are these pre-compiler errors unrelated and I'm missing something? Any help greatly appreciated.
Last updated: 2024-04-04

Post by ewi04 on Git - User identification data is lost when codesys is closed ^{CODESYS Forge talk (Post)}
Hallo, it's not a big problem, but it is a bit annoying. The git user identification data is lost when codesys is closed. So I have to enter the information again and again. Is there a way to save the data? Environment: Codesys V3.5 SP19 Patch 4 (64Bit), Git 1.3.0.0 Thanks
Last updated: 2023-11-22

Post by fazlinda on AWS IoT core CODESYS ^{CODESYS Forge talk (Post)}
Hi, Im having a problem sending a data from my structure text code from codesys to aws. Instead of receiving {state {reported {data: 123}}} It display {state {reported {data: 123}}}\x00 \x00 \x00 \x00 \x00 \x00 \x00 Please help me solve this issues. how to remove \x00 ?
Last updated: 2023-12-06

Post by fazlinda on AWS IoT core CODESYS ^{CODESYS Forge talk (Post)}
Hi, Im having a problem sending a data from my structure text code from codesys to aws. Instead of receiving {state {reported {data: 123}}} It display {state {reported {data: 123}}}\x00 \x00 \x00 \x00 \x00 \x00 \x00 Please help me solve this issues. how to remove \x00 ?
Last updated: 2023-12-06

Post by fazlinda on AWS IoT core CODESYS ^{CODESYS Forge talk (Post)}
Hi, Im having a problem sending a data from my structure text code from codesys to aws. Instead of receiving {state {reported {data: 123}}} It display {state {reported {data: 123}}}\x00 \x00 \x00 \x00 \x00 \x00 \x00 Please help me solve this issues. how to remove \x00 ?
Last updated: 2023-12-06

Post by fazlinda on AWS IoT core CODESYS ^{CODESYS Forge talk (Post)}
Hi, Im having a problem sending a data from my structure text code from codesys to aws. Instead of receiving {state {reported {data: 123}}} It display {state {reported {data: 123}}}\x00 \x00 \x00 \x00 \x00 \x00 \x00 Please help me solve this issues. how to remove \x00 ?
Last updated: 2023-12-06

Post by fazlinda on AWS IoT core CODESYS ^{CODESYS Forge talk (Post)}
Hi, Im having a problem sending a data from my structure text code from codesys to aws. Instead of receiving {state {reported {data: 123}}} It display {state {reported {data: 123}}}\x00 \x00 \x00 \x00 \x00 \x00 \x00 Please help me solve this issues. how to remove \x00 ?
Last updated: 2023-12-06

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