Modbus comunication with a PC software ^{CODESYS Forge talk (Thread)}
Modbus comunication with a PC software
Last updated: 2022-06-20

CODESYS v3+ WAGO PFC200+ MODBUS RTU ^{CODESYS Forge talk (Thread)}
CODESYS v3+ WAGO PFC200+ MODBUS RTU
Last updated: 2017-11-03

Modbus Address Range Problem ^{CODESYS Forge talk (Thread)}
Modbus Address Range Problem
Last updated: 2015-09-17

CodeSys2.3, WAGO750-8202, ModBus ^{CODESYS Forge talk (Thread)}
CodeSys2.3, WAGO750-8202, ModBus
Last updated: 2023-06-30

Modbus Funktionen mit PLC Programm ^{CODESYS Forge talk (Thread)}
Modbus Funktionen mit PLC Programm
Last updated: 2007-09-12

Globale Variable über Modbus auslesen ^{CODESYS Forge talk (Thread)}
Globale Variable über Modbus auslesen
Last updated: 2009-05-28

cyclic connection to several modbus slaves ^{CODESYS Forge talk (Thread)}
cyclic connection to several modbus slaves
Last updated: 2016-07-13

Siemens V20 Frequenzumrichter über Modbus RTU ^{CODESYS Forge talk (Thread)}
Siemens V20 Frequenzumrichter über Modbus RTU
Last updated: 2024-03-21

Modbus writing on value change ^{CODESYS Forge talk (Thread)}
Modbus writing on value change
Last updated: 2024-04-03

Slow modbus digital input response ^{CODESYS Forge talk (Thread)}
Slow modbus digital input response
Last updated: 2024-04-15

IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Thread)}
IoDrvModbusTCP_Diag not defined when using MODBUS
Last updated: 2024-05-29

Modbus Client Request Not Processed ^{CODESYS Forge talk (Thread)}
Modbus Client Request Not Processed
Last updated: 2024-05-30

Modbus write via FB failure ^{CODESYS Forge talk (Thread)}
Modbus write via FB failure
Last updated: 2025-11-06

Modbus connection via Qronox PCD3 M6893 ^{CODESYS Forge talk (Thread)}
Modbus connection via Qronox PCD3 M6893
Last updated: 2026-02-19

PFC200 - WAGO 750-8202 - MODBUS RTU ^{CODESYS Forge talk (Thread)}
PFC200 - WAGO 750-8202 - MODBUS RTU
Last updated: 4 days ago

PFC200 - WAGO 750-8202 - MODBUS RTU ^{CODESYS Forge talk (Thread)}
PFC200 - WAGO 750-8202 - MODBUS RTU
Last updated: 4 days ago

Post by jacobwago on v3.5 SP19 - Modbus TCP Devices - Channel Limit? ^{CODESYS Forge talk (Post)}
Hello, I have experienced the same issue as described above but for the Modbus Serial configurator. Looking for a solution. In v3.5 SP19 Patch 7 the Modbus Serial Master Slave configurator has a "virtual" limit of 10 channels. In v3.5 SP18 Patch 5 this virtual limit does not exist. I can successfully copy back and forth from 18 to 19 with out any build error. However, this is not a good solution for our customers. What is even more confusing is that the IoDrvModbus library is the same version (4.3.0.0) for both SP18 and SP19. Please help in providing a fix to the virtual channel limit of 10 in SP19. Thanks,
Last updated: 2024-09-29

Post by timl on Application has invalid license metrics ^{CODESYS Forge talk (Post)}
Hallo, ich habe eine Control for Linux SL auf der ich einen TCP Modbus Master anlege, mit dem ich einen Slave auslesen möchte. Das Anlegen funktioniert soweit alles, sobald ich beim ModbusTCPSlaveE/A-Abbild in den Channel eine Variable einfüge, damit ich den Channel auslesen kann, kommt es beim übertragen auf die SPS zu einem Ausnahmefehler. Im Anhang noch eine Bilder der Fehlermeldung und der installierten Lizenzen. CODESYS Version ist V3.5 SP19 Patch 4 Meinem Verständnis nach ist die Modbus Lizenz mit in der Control Standard L inbegriffen und auch in der Lizensierten Softwaremetrik sehe ich keine überschreitung meiner Lizenzbegrenzungen. Daher verstehe ich nicht wieso ich diesen Fehler bekomme und eine auslesung via Modbus nicht möglich ist. Gruß Tim
Last updated: 2024-05-08

Post by nulltrace on How change Unity-ID in TCP Modbus Slave ^{CODESYS Forge talk (Post)}
Please explain how you configured that. Normaly, the Server should answer to all UID as long as gateway isn't activated. With activated gateway all UID will be forwarded to Serial-Interface, in taht case 255 has to be used for Gateway-Diagnostics. So that means, there is somethink wrong on your configuration. Which CDS-Version, Which Runtime-Version and so on are used.
Last updated: 2026-04-01

Post by timvh on Dynamically enabling/disabling Modbus slave devices in runtime (performance issue with timeouts) ^{CODESYS Forge talk (Post)}
As far as I remember, the Reconfigure functionality doesn't work for Modbus devices. But... Each Modbus device in your device tree has a name. You can set the property "Enable" of this device to FALSE to stop communicating with it. So if one of your Modbus Slave devices name is "MbSlave1" in the device tree, then in your code you can set the Enable to FALSE to let it stop communicating: MbSlave1.Enable := FALSE; Please let us know if this worked on your controller with your application and your CODESYS version. Alternatively you could use the ModbusFB library. See: https://forge.codesys.com/prj/codesys-example/modbus/home/Home/
Last updated: 2025-08-13

Post by iliyatsukerman on SoftMotion auf PFC200 ^{CODESYS Forge talk (Post)}
Hallo, Wir würden Ihre Unterstützung bei der Überprüfung der Kompatibilität der folgenden Konfiguration sehr schätzen: • PSTR-LO-16/400FEV ELMO • SCALANCE XC208 • WAGO PFC200 750-8213/40-010 • Die SPS (WAGO) wird gleichzeitig eingesetzt als: o EtherCAT-Master zur Kommunikation mit einem Elmo-Servoantrieb (EtherCAT-Slave, 4 Achsen – generisches CiA 402-Profil), und o Modbus-TCP-Server zur Kommunikation mit einem Siemens Modbus-TCP-Client, welcher zur Fernsteuerung des Elmo-Servoantriebs über die SPS dient. Bitte bestätigen Sie, ob die SPS in der Lage ist, diese Dualfunktion — als EtherCAT-Master und gleichzeitig als Modbus-TCP-Server — ohne Konflikte oder Performanceprobleme zu unterstützen. Insbesondere interessiert uns, ob die CODESYS SoftMotion SL Basislizenz (2305000000-F) notwendig ist, um 4 Servoachsen zu steuern, und ob diese Lizenz auf einer WAGO PFC200 SPS mit CODESYS Version 3.5 Service Pack 19 Patch 40 oder höher unterstützt wird. Alle Achsen im Servoantrieb werden unabhängig voneinander gesteuert. Mit freundlichen Grüßen. ILIYA
Last updated: 2025-07-13

Post by mavitia on Application based license problem - Modbus TCP ^{CODESYS Forge talk (Post)}
I am running ubuntu on a raspberry pi, and installed an application based license Control Basic M on it, it runs a demo program fine, does not timeout etc. however, when I add a modbus TCP device, I start getting errors: <Entry severity="error" component="CmpApp" user="nobody" timestamp="12/18/2023 3:49:42 PM" infoId="24">Online change denied. Application Application is in exception state!</Entry> <Entry severity="error" component="CmpApp" user="nobody" timestamp="12/18/2023 3:49:42 PM" infoId="68">Download failed: Application=Application</Entry> <Entry severity="exception" component="CmpApp" user="nobody" timestamp="12/18/2023 3:49:41 PM" infoId="0">Application app=Application has invalid license metrics!</Entry> the modbus tcp slave runs, and the counter ticks up, however, when I call the variables on the %IX0.0 in my program, and try to upload the changes, I am getting the error messages which stop the program as far as I understand, the application based, M includes 2 fieldbus instances, but on the other side is fairly new, anything obvious I am missing out here?
Last updated: 2023-12-18

Post by aris on Modbus write via FB failure ^{CODESYS Forge talk (Post)}
Hi all, I am using CoDeSys V3.5 and a soft controller Win V3x64. I am trying to read a modbus slave via Function Blocks and not via the channels of the hardware tree for the Slave. I created some requests of type ModbusRequest and I notice that I can read Input Registers and Coils but I can not write Holding Registers and Coils. I am using the library IoDrvModbusTCP 4.1.0.0. When i just use a single modbus request with FC06 (or FC16), there is no request sent to the slave and although the xExecute takes its true value from a pulse of 2 seconds duration, I take almost every 3 minutes an error "TCP_COMMUNICATION_ERROR - 16#A5 - TCP Port. error. Request was not sent". My code is ok because if i change the function code for reading registers, everything works fine. Did anyone have this issue in the past? Thank you in advance.
Last updated: 2025-11-06

Post by itsthefabs on (no subject) ^{CODESYS Forge talk (Post)}
Hallo zusammen, ich nutze eine Wago 8212 als Modbus Client (in früheren Codesys Versionen hieß der Modbus Master) und habe einen weitere Wago 8212 als Modbus Server (früher Modbus Slave). Bisher habe ich für den Client den Funktionsblock FbMbMasterTcp aus der WagoAppPlcModbus-Library genutzt. Zukünftig würde ich das allerdings gerne über das Anhängen eines Modbus-Geräts am Ethernet-Knoten im Projektbaum realisieren. Zum besseren Verständnis habe ich ein Bild beigefügt. Der Modbus mit dem Server läuft auch. Kommt es allerdings zum Fehler des Modbus, z.B. kurzzeitig keine Verbindung oder timeout, wird der Fehler nicht automatisch quittiert. Ich muss dann manuell über den Status des Server-Knotens einen Button mit "Bestätigen" drücken. Im Betrieb kann ich mich aber nicht jedes Mal einloggen um einen Fehler zu quittieren. Gibt es hier irgend einen Trick, wie ich das aus dem Programm-Code quittieren kann? Vielen Dank schon einmal.
Last updated: 2025-02-26

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

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