Post by zdenekkrejci on Issues with Modbus Slave with Raspberry Pi ^{CODESYS Forge talk (Post)}
Did you find out what was wrong? I have the same issue
Last updated: 2025-03-09

Post by eschwellinger on ModbusTCP RaspberryPi zu Fronius Wechselrichter ^{CODESYS Forge talk (Post)}
Schreibe den Slavename(der vom Gerätebaum) in ein Watchfenster dann siehst du Instanz des Modbus Slave Fb's und hast dadurch Diagnose Info
Last updated: 2025-07-04

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 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 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 hwopereis on How to use Application Trigger in Modbus TCP Server ^{CODESYS Forge talk (Post)}
I'm now circumventing the problem by creating a separate TCP client for all Write actions. Upon registering a changed variable, I enable this client, until the change is processed.
Last updated: 2024-07-01

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 husarz17 on How change Unity-ID in TCP Modbus Slave ^{CODESYS Forge talk (Post)}
My codesys is 3.5.21.30. I am using function ModbusServer from library ModbusTCP_Slave. The reason is that I need share 9000 Holding registers. By standard configuration it is only 4096. fbMbTcpDevice: ModbusTCP_Slave.ModbusServer; fbMbTcpDevice( wPort := 502, pInputData := ADR(awInputReg), pOutputData := ADR(awHoldingReg), uiInputDataSize := 10, uiOutputDataSize := 9000, xEnable := TRUE, tTimeout := 10000, InterfaceName := "eth0", xBusy => xBusy, xError => xError, byClientConnections => byConnections ); Ethernet port is cofigured: Network interface: eth0 IP address: 10.10.22.55 Subnet maskL 255.255.255.0 Default gateway: 0.0.0.0 And it only works when I am reading registers with ID 255 by Modbus Poll. Any other IDs don't work. The actual TCP client device try to read registers with ID 1 and I can't change it... Thanks in advance for your help!
Last updated: 2026-04-01

Post by jacobwago on v3.5 SP19 - Modbus TCP Devices - Channel Limit? ^{CODESYS Forge talk (Post)}
Hello All, The solution is updating SP19 Modbus version from 4.3.0.0 to 4.4.0.0 (see attached image for bug fix). Thank you,
Last updated: 2024-09-30

Post by timvh on Modbus TCP & RTU with Control for Linux SL ^{CODESYS Forge talk (Post)}
Most likely your IP address is set to 172.... because you use a VPN connection to your device. Probably best to use the other Ethernet interface for your modbus communication.
Last updated: 2024-10-24

Post by cmason on v3.5 SP19 - Modbus TCP Devices - Channel Limit? ^{CODESYS Forge talk (Post)}
There still is no solution to this. I am running Modbus version 4.4.0.0 and it still wont let me add more than 10 channels. Does anyone have a solution for this?
Last updated: 2025-09-05

Post by cmason on v3.5 SP19 - Modbus TCP Devices - Channel Limit? ^{CODESYS Forge talk (Post)}
There still is no solution to this. I am running Modbus version 4.4.0.0 and it still wont let me add more than 10 channels. Does anyone have a solution for this?
Last updated: 2025-09-05

Post by gorditron on Modbus Slave RTU in der Applikation abschalten ^{CODESYS Forge talk (Post)}
Hallo, gibt es eine Möglichkeit die Modbus Slaves (ModbusSlaveComPort) innerhalb der Applikation über ein Variable zu aktivieren oder zu deaktivieren? Bilder als Datei Danke!
Last updated: 2023-11-09

Modbus Worte in Real umwandeln ^{CODESYS Forge talk (Thread)}
Modbus Worte in Real umwandeln
Last updated: 2017-01-01

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Last updated: 2010-08-01

Codesys V3 and Enron Modbus ^{CODESYS Forge talk (Thread)}
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Last updated: 2022-11-09

Modbus RTU Master on Windows SoftPLC ^{CODESYS Forge talk (Thread)}
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Last updated: 2021-06-22

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Last updated: 2023-12-05

Change modbus server parameters from program ^{CODESYS Forge talk (Thread)}
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Last updated: 2024-07-16

Change modbus server parameters from program ^{CODESYS Forge talk (Thread)}
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Last updated: 2025-03-17

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Last updated: 2025-09-04

Modbus zwischen 750-841 und Raspberry ^{CODESYS Forge talk (Thread)}
Modbus zwischen 750-841 und Raspberry
Last updated: 2016-01-04

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