Post by uluking on CodeSys2.3 Modbus 64-Bit Double Read Problem ^{CODESYS Forge talk (Post)}
Hi everyone, I would appreciate your help with a problem I've been working on for a few days but haven't been able to resolve. I am reading data from a Siemens PAC3220 energy analyzer using Modbus with Wago-8202. However, the device's energy indices are given as doubles. Since a double variable is 64-bit, it is not possible to read it directly. I have been struggling for days, I have written many conversion functions but I have not been able to get results. I would appreciate your help. I read 4 word variables and processed them. I am converting them according to IEEE-754, but I can't seem to read the correct data. I would appreciate your help.
Last updated: 2025-10-27

Post by uluking on CodeSys2.3 Modbus 64-Bit Double Read Problem ^{CODESYS Forge talk (Post)}
Hi everyone, I would appreciate your help with a problem I've been working on for a few days but haven't been able to resolve. I am reading data from a Siemens PAC3220 energy analyzer using Modbus with Wago-8202. However, the device's energy indices are given as doubles. Since a double variable is 64-bit, it is not possible to read it directly. I have been struggling for days, I have written many conversion functions but I have not been able to get results. I would appreciate your help. I read 4 word variables and processed them. I am converting them according to IEEE-754, but I can't seem to read the correct data. I would appreciate your help.
Last updated: 2025-10-27

Post by struccc on Problem Reading Registers via Modbus from non Codesys device ^{CODESYS Forge talk (Post)}
Hi, Might be a good idea first to try out the connection and the device with some handy software, like Modbus Poll. There you can see better, what's really going on... - Is it really connected? - What error code does it return? - Can it read from the register address? - Maybe try Input registers and Holding Registers - can make a difference - Sometimes register addresses are messed up: shifted +-1 (mixing of 2 standards) - Sometimes register addresses start with offset 30000, 40000 ... - Are you using the right protocol? - Is it RTU or TCP? Maybe ASCII? - Can even have a look at the data packets, etc... All this is easier to figure out first with some modbus utility... and then to set it up in CODESYS should not be an issue. P.
Last updated: 2025-03-09

Post by mbmik on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
Hi Im trying to setup a Weidmüller WL2000 to run with MODBUS, to get some data from a server. Codesys V3.5 SP20. The issue is, that whenever i attach an ethernet port and add MODBUS Master und also a Slave, codesys will compile the project, but there always seem to be some remaining errors, which or only visible, when setting the messages window to "Pre-Compiled". I tried a lot of stuff to get rid of these errors, but cant find to seem the reason. New installation of codesys, cleaned project, setup completely empty new project, manually adding libs. Nothing helps. Any help is apreciated. Maybe we are doing something wrong.. Example Project is available, if somebodey wants to take a look. Greetings and thanks alot
Last updated: 2024-04-15

Post by schorge on Modbus RTU Slave ^{CODESYS Forge talk (Post)}
Ich würde gerne bestimmt Modbus RTU Slave Adressen auslesen, leider bekomme ich keine Werte vom Bus. Verbindung erfolgt über einen Raspberry mit Modbus RS485 Adapter, welcher erfolgreich verbunden ist. Mit einem IOBroker kann ich die Daten erfolgreich auslesen. In der Modbus_COM_Port => Modbus_Serial_Device habe ich Input Register 4000 %QW und Startadressen auf Input Register 3000, als Variable ein Array[0..2999] of Word, kann aber keine Werte auslesen.
Last updated: 2023-12-06

Post by dengsberg on Disable Communications to 'Modbus_Server_COM_Port' from the logic ^{CODESYS Forge talk (Post)}
I have a serial Modbus RTU communicating to the Slave device. But when the control system is not in Run there is no power applied to one of the Modbus Devices. Can I enable / disable the communications to that Modbus Slave in the code based on my running mode, so I don't get all the errors?
Last updated: 2024-08-29

Post by bolopg on MODBUS TCP REGISTERS CODESYS V3.5 ^{CODESYS Forge talk (Post)}
Hi. I have a problem with MODBUS TCP MASTER. I treid to read HR in range 3027-3037 but I cannot read them. I have modbus slave chanel with offset 0x3037. I checked what I read and it looks like I am reading HR in range 1-10. What I am doing wrong.
Last updated: 2024-10-11

Post by wbj0t on one variable signed to modbus tcp server device and modbus serial device ^{CODESYS Forge talk (Post)}
Hi. Raspberry pi 4 runtime. Runtime version 4.16, IDE version 3.5.21. Is it possible write new value for variable via modbus tcp or serial devices when both enabled? As I see - not. What can I do? It is terrible restriction.
Last updated: 2025-07-17

Post by hinet on 22kW Wallbox mit Modbus ^{CODESYS Forge talk (Post)}
Hallo an alle, ich schaue mir gerade ein paar 22kW Wallboxen an: https://shop.einfacheauto.de/collections/22-kw-wallboxen Mir wäre vor allem wichtig, dass die Kommunikation per Modbus gut funktioniert. Es werden zwar ein paar Wallboxen gelistet, die Modbus ermöglichen, trotzdem wollte ich euch nach Erfahrungen fragen, welche Modelle in der Hinsicht besonders problemfrei funktionieren.
Last updated: 2025-11-06

Post by ahuckphin on Issues with Modbus Slave with Raspberry Pi ^{CODESYS Forge talk (Post)}
I have a DFRobot RS485 temperature & humidity sensor (SEN0438) connected to my Raspberry Pi via a USB to RS485 adapter. I am able to connect and read the sensor data when running a python code locally. However in Codesys, I encounter this error "A bus error has occurred." and "There was no response in time". Could this be because of Modbus Server Channel and Modbus Server Init configuration on my part? Admittedly I am new to Codesys. To get to this stage, I: 1. added some lines to CODESYSControl_User.cfg 2. added "Modbus_COM" in Codesys and set "Serial Port Configuration" under "General" 3. added "Modbus_Master_COM_Port" in Codesys and checked transmission mode is set to "RTU" 4. added "Modbus_Slave_COM_Port" in Codesys and checked server address is set to 1 (also set 1 in my sensor) 5. added 1 channel and 1 init for "Modbus_Slave_COM_Port" under "Modbus Server Channel" and "Modbus Server Init"
Last updated: 2024-07-10

Post by timvh on Accessing ModbusTCP addresses from python ^{CODESYS Forge talk (Post)}
https://en.wikipedia.org/wiki/Modbus
Last updated: 2023-09-20

Post by ahuckphin on Issues with Modbus Slave with Raspberry Pi ^{CODESYS Forge talk (Post)}
duplicate
Last updated: 2024-07-11

Post by dohy on Modbus RTU Response CRC fail ^{CODESYS Forge talk (Post)}
Did you resolve it?
Last updated: 2024-09-19

Post by ph0010421 on MODBUS TCP REGISTERS CODESYS V3.5 ^{CODESYS Forge talk (Post)}
hello Use FC3 instead of FC4
Last updated: 2024-10-11

Post by bartspako on Connection between Beijer PLC and Schneider Tesys-Island using Modbus TCP ^{CODESYS Forge talk (Post)}
Last updated: 2024-10-16

Post by dkugler on STRING size and reading STRING with Modbus ^{CODESYS Forge talk (Post)}
Last updated: 2025-01-31

Post by sandro66 on Application-based license Modbus Channels ^{CODESYS Forge talk (Post)}
Hi Gatto, Using version 3.5.21.xx, it is no longer possible to use Modbus function blocks (I make extensive use of these FBs.)as shown in the example. https://content.helpme-codesys.com/en/CODESYS%20Examples/_ex_modbus_example.html The compiler detects one Modbus instance for each instance of the communication FB block. The example program above, although simple, reports 8 Modbus instances when compiled with the latest version. Codesys Support says that you must use fieldbus I/O mapping, but this will result in the loss of the ability to programmatically modify communication parameters. Sandro
Last updated: 2025-09-04

Post by eschwellinger on IoDrvModbusTCP_Diag not defined when using MODBUS ^{CODESYS Forge talk (Post)}
known issue hopefully solved to next version
Last updated: 2024-04-18

Post by tobifenny on Modbus TLS Kommunikation ^{CODESYS Forge talk (Post)}
Ich habe eine Wallbox, die ich gerne per Modbus ansteuern würde. Die Normale Modbus-Kommunikation, um ein paar Werte auszulesen klappt auch. Wenn ich aber Zugriff auf bestimmte Modbus-Register haben möchte, benötigt die Wallbox ein TLS-Zertifikat. Das Zertifikat habe ich bereits erstellt und im Security-Sreen unter Eigene Zertifikate hochgeladen. Weiter komme ich aber nicht mehr. Wie baue ich eine TLS-Verbindung mit der Waalbox auf? Vielleicht hat das ja schonmal jemand gemacht und ein Beispiel für mich. Ich bin über jede Hilfe sehr Dankbar!
Last updated: 2025-11-05

Post by milan-svarny on ModbusFB.ClientSerial Problem with Reply Timeout ^{CODESYS Forge talk (Post)}
Hi All, I have problem with ModbusFB.ClientSerial. I'm using 4 different port for Modbus communication. After some time of running program ClientSerial stops to receive data to reply buffer and all request finish with Reply Timeout. The Device sent reply correctly,that it is visible on oscilloscope and it is possible to see that data( reply )are in the device. If the usbtty device is read over external app. then it is possible to see all data which were not taken by ModbusFB.ClientSerial. The stack does not overflow or something , program runs correctly forward and no exceptions or something. The main problem it is that when the error occur than it is not possible to reset port or something or maybe i'm doing it wrong way. please help me with this issue. Thank you for any help in advice Milan
Last updated: 2025-05-23

Post by sumit on Not able to see input data coming from eip adapter on codesys ^{CODESYS Forge talk (Post)}
Hello there, I have an eip adapter running (remotely) that is sending data back to eip scanner (running on codesys). I can send data from scanner (codesys) to the adapter but not getting the data back from the adapter. I have verified the incoming data on wireshark but I don't see this data in the codesys. I have tried local variable mapping and global variable mapping not variable values just stays at 0. Please guide.
Last updated: 2024-02-29

Hi, I try to send and receive data using a UDP connection via SysSocket 3.5.17.0. While sending data works fine, I have problems with the receiving part. I am able to capture the received data of client side in wireshark But unable to capture it on the codesys ^{CODESYS Forge talk (Thread)}
Hi, I try to send and receive data using a UDP connection via SysSocket 3.5.17.0. While sending data works fine, I have problems with the receiving part. I am able to capture the received data of client side in wireshark But unable to capture it on the codesys
Last updated: 2024-06-03

Post by paulorb on STRUCT AT %MW1000 ^{CODESYS Forge talk (Post)}
Hi I am trying to use STRUCT to parse commands from Modbus/TCP, Modbus client will fill the bytes related to a specific command (type, parameters), then PLC (Codesys) will access the command parameters. A STRUCT will simplify a lot the process of parsing the data, so I don't need to parse byte per byte, address will be mapped to a struct and I can use it for parsing the data. From what I understood, the compiler does not allow me to specify the location of the struct for a %MW register. VAR_COMMAND AT %MW1002: structGenericModbusCommand; This will throw: Bad declaration, use '%ML' for 'structGenericModbusCommand' variable But If I change it to %ML, when you go online you see that it is actually allocating the struct in another memory address. When we go online, on GVL we can see: VAR_COMMAND. structGenericModbusCommand %ML1002 commandType COMMANDTYPE %MB8016 ... %MB8020 I am not specifying a pointer or a reference it is a struct type, why is it mapping to a %MW location (random one). How can I control where it is mapping to? I need a consistent way to map STRUCT to specific modbus address. Is it possible? Thanks, Paulo Note I am using a Codesys OEM: Schneider Machine Expert Logic Builder (M241)
Last updated: 2024-08-13

Post by laazik2 on v3.5 SP19 - Modbus TCP Devices - Channel Limit? ^{CODESYS Forge talk (Post)}
I am actually wondering as well if there are plans to fix it or not? As adding two modbus devices creates it's own problems with connection limits and other issues, which some slave devices have.
Last updated: 2023-09-05

How to use more 4 instances of CANopen/Profibus/Modbus with The application-based license CODESYS Control ^{CODESYS Forge talk (Thread)}
How to use more 4 instances of CANopen/Profibus/Modbus with The application-based license CODESYS Control
Last updated: 2023-11-02

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