Post by olehmann03 on PFC200 - WAGO 750-8202 - MODBUS RTU ^{CODESYS Forge talk (Post)}
Hello, I’m working on implementing Modbus RTU communication with a Carel controller (CPCO). I want to use the front RS485 interface through the DB9 connector. The issue is that I can’t get the communication working correctly. Below are the steps I’ve done so far: Connected pins 3 and 8 from the DB9 connector to the +/- RX/TX terminals on the Carel side. In the PLC shell, I set serialmode to RS485. In WBM under Administration > Serial Interface > Assign owner of serial interface, I set the port to unassigned. In the device tree, I created Modbus_COM with the following settings: COM port: 1 Baud rate: 19200 Parity: None Stop bits: 1 Created a Modbus client on this COM interface in RTU mode. Under the status tab, I can see it is in running state. On the client, I created a Modbus server and set the Modbus address of my unit to 1. Defined a few channels as FC03 to read holding registers according to the Carel register map. I checked the communication with the Carel controller using a USB-to-RS485 converter connected to my PC, and communication works correctly there. In the status tab, I can see that the Modbus server is polling, but there is no response from the controller. I also tried multiple times swapping A/B lines on the Carel side, but it did not help. Do you have any suggestions on what else I should check?
Last updated: 2026-05-22

Post by solidlogicguy on Little endian to Float from Modbus RTU ^{CODESYS Forge talk (Post)}
Hello, I got a device from which I require to read values from I am using a WAGO PLC 750-8212 and I am communicating through Modbus Master FUNCTION BLOCK from library WagoAppPLCModbus in Codesys 3.5 to this device. I already receive data from the device that is a CVM to monitor voltage from a fuel cell. The technical support of the company that makes these devices says that the data is sent in little endian form. And I want to convert it to a float value. The tech support sent me the next instructions of how to do it but I am new using codesys, so any advice or help I will really appreciate so much. Message from tech support: The process is complicated, better to do it with already implemented library in the language/program you use. Basically the process should be next: To convert the two Modbus registers containing parts of a 32-bit float in little-endian byte order to a floating-point number using mathematical operations, you first need to combine the two 16-bit integers (assuming reg1 is the lower word and reg2 is the higher word) and then interpret the result according to the IEEE 754 standard. Given: - Register 192 (reg1) = 4096 - Register 193 (reg2) = 14884 Step 1: Combine the two registers. Since we are dealing with little-endian byte order, reg2 is the high word, and reg1 is the low word: combined = reg2 * 2^16 + reg1 combined = 14884 * 65536 + 4096 combined = 975175680 + 4096 combined = 975179776 Step 2: Convert the combined value to binary: combined_binary = '1110101101011100000000000000000' Step 3: Split the binary into IEEE 754 components: Sign bit (1 bit): 0 Exponent (8 bits): 11101011 Mantissa (23 bits): 01011100000000000000000 Step 4: Convert the binary exponent to decimal and subtract the bias (127 for 32-bit floats): exponent = int('11101011', 2) - 127 exponent = 235 - 127 exponent = 108 Step 5: Calculate the mantissa as a fraction: The mantissa in IEEE 754 format is the fractional part after the leading 1 (which is implicit). Therefore, we need to convert the binary mantissa to decimal and add the implicit leading 1: mantissa_fractional = 1 + int('01011100000000000000000', 2) / 2^23 mantissa_fractional = 1 + 18688 / 8388608 mantissa_fractional = 1 + 0.002227783203125 mantissa_fractional ≈ 1.002227783203125 Step 6: Combine the sign, exponent, and mantissa to get the float value: float_value = (-1)^0 * mantissa_fractional * 2^exponent float_value = 1 * 1.002227783203125 * 2^108 Because the exponent is quite large, the resulting float value is a very large number.
Last updated: 2023-12-15

Post by timvh on ernesto881124 ^{CODESYS Forge talk (Post)}
You will need a USB to RS485 converter to connect the PC to the Modbus RTU Slave Device. In Windows this converter will be recognized as Serial COM poort (e.g. COM2, or COM3, see the windows device manager to find this out). Select this port in your CODESYS application. On the PC you need to use the CODESYS Control Win (SoftPLC) to run your application. It will not work in simulation mode, because then the Modbus Communication will not be activated.
Last updated: 2023-09-14

Post by ofey on Device parameter - ‘ModbusTCP Configuration’ ^{CODESYS Forge talk (Post)}
Hi! Do anybody know how I can add and enable the parameter 'Default Modbus TCP slave' on a device? I am currently writing a program where the PLC shall be set up as a Modbus TCP client, but I dont know how to add parameters to devices in codesys. I'm pretty new to the codesys environment. The picture in the attachment is on a similar PLC project where I have not written the code. my goal is to add this parameter in another project.
Last updated: 2023-10-04

Post by ofey on Symbol configuration / GVL ^{CODESYS Forge talk (Post)}
Hi! I have som variables that I communicate to a Modbus Master. These variables are declared in a "Global Variable List" where I have assigned them memory addresses. To organize this mapping I want to make a MODBUS list where I show all the variable names together with the memory address. Is there an easy way to export this list from CODESYS? Either through script or some export function maybe?
Last updated: 2023-10-11

Post by ofey on Symbol configuration / GVL ^{CODESYS Forge talk (Post)}
Hi! I have som variables that I communicate to a Modbus Master. These variables are declared in a "Global Variable List" where I have assigned them memory addresses. To organize this mapping I want to make a MODBUS list where I show all the variable names together with the memory address. Is there an easy way to export this list from CODESYS? Either through script or some export function maybe?
Last updated: 2023-10-11

Post by nano on Issues with Modbus Slave with Raspberry Pi ^{CODESYS Forge talk (Post)}
in the codesyscontrol.cfg or codesyscontrol_user.cfg you have to declare whoch comport-ports from runtime are used. please tell us how the comport is called in linux an post the codesyscontrol.cfg files also write down here, which parameters are used in the python-script and what is parameteized in the modbus-master-comport of your codesys-application. mostly the errors occurs in ine of these areas
Last updated: 2024-07-11

Post by winki on Modbus TCP Client ^{CODESYS Forge talk (Post)}
Hello, I am new on CODESYS env. I would like to do some Modbus TCP, but I am wondering If using codesys you must use the device "Modbus_TCP_Client" & "Modbus_TCP_Server". I would like to do it without device, only using ST. Is that possible ? I try the example : MODBUS_master_example, but it is not working. If it is possible to dot it without any Device I will show my code. Thx a lot
Last updated: 2024-10-25

Post by selim on Need help to get RS-485 signal in Cosesys . ^{CODESYS Forge talk (Post)}
Hello Mr./Ms., I invested Raspberry Pi lot of time to get the output from the raspberry PI5. But, i did not get the signal. I use a raspberry pi 5> RS485 can hat > Modbus RTU, Industrial 8-ch analog acquisition module >weight transmitter jy-s60> S-load cell. I did not able to receive the signal from Modbus RTU to Raspberry PI5 where I use the RS 485 serial connection.
Last updated: 2024-12-01

Post by gabrielarffa on Modbus TCP/IP having problems with global variables ^{CODESYS Forge talk (Post)}
I'm using Modbus TCP/IP to communicate Codesys with Elipse E3 as the master for a college project. I have made a list of global variables to organize the programming in two different POUs. The problem is, when I try to do the mapping of variables, the program informs me of an error due to the identifiers having a "." on their names. Do I have to reorganize my code to make it an unified block or is there a way to declare their names without changing all the code structure?
Last updated: 2025-05-20

Post by gabrielarffa on Modbus TCP/IP having problems with global variables ^{CODESYS Forge talk (Post)}
I'm using Modbus TCP/IP to communicate Codesys with Elipse E3 as the master for a college project. I have made a list of global variables to organize the programming in two different POUs. The problem is, when I try to do the mapping of variables, the program informs me of an error due to the identifiers having a "." on their names. Do I have to reorganize my code to make it an unified block or is there a way to declare their names without changing all the code structure?
Last updated: 2025-05-20

Post by yannickasselin on Dynamically enabling/disabling Modbus slave devices in runtime (performance issue with timeouts) ^{CODESYS Forge talk (Post)}
I would definitely try using the "Reconfigure" function block from "CAA Device Diagnosis@ library. https://content.helpme-codesys.com/en/libs/CAA%20Device%20Diagnosis/3.5.17.0/CAA-Device-Diagnosis/Function-Blocks/Reconfigure/Reconfigure.html#:~:text=This%20function%20block%20reads%20and,take%20effect. Although I have not tried it with Modbus, I had great success with EtherNet/IP, Profinet and EtherCAT. You can also have a look at the other functions in this library. There are useful functions to help iterate through all the nodes under a master node.
Last updated: 2025-08-12

Post by ofey on EtherCAT fieldbus ^{CODESYS Forge talk (Post)}
Okey, thank you! Do you think it is something in this library, that makes it possible to do the configuration in a PRG? https://content.helpme-codesys.com/en/libs/IODrvEtherCATDriver/Current/IoDrvEtherCAT.html#id1 I think the codesys modbus libraries support configuration and connection to modbus slaves without having to add the slave devices in the device tree. Just do it from function blocks inside the program. I was hoping for something similar with EtherCAT.
Last updated: 2024-04-10

Post by ph0010421 on ModbusTCP_FunctionCode06 ^{CODESYS Forge talk (Post)}
Hi You can add a channel to the standard Modbus TCP library with FC06. From the device tree, add Ethernet device, ModbusTCP master then finally a ModbusTCP slave (your power meter). You can add read/write channels (for any FC) in here. As you add these devices, the necessary libraries will be inserted for you. Alternatively, I have a ModbusTCP client/server library if your RT doesn't have Modbus (I think they all do these days?)
Last updated: 2026-05-18

Post by duvanmoreno24 on Modbus writing on value change ^{CODESYS Forge talk (Post)}
Yes, I tried to do what you put in the first code. However, I have a problem with that and that is that the inputs must be declared with the type. I have many data types running in my code (real, int, uint, bool) and I can't put them in the same function, another thing is that I need to instantiate that function for everything I want to write to the slave. You put a for to 200 but it means that it has to be the same data type and inside the array, but I want to get them individually. I'm struggling to do it in a good and efficient way like wago's E-cockpit does. in the first screenshot you can see, you simply type in value, change the package of things you want to write in value change and it does everything by itself automatically, without comparing any old and new values and even less having the need to activate a bool. , it is perfect.
Last updated: 2024-04-03

Post by anonymous on 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 (Post)}
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 data of client side in wireshark but i am unable to capture it in the codesys. Heres the below part of code of client side. PROGRAM POU_udpclient_program VAR istep : INT := 1;//step variable for state machine xStart: BOOL;// Flag to start the UDP protocol iecSocketId: syssocket_interfaces.RTS_IEC_HANDLE;//socket handle for receiving iecCreateResult: syssocket_interfaces.RTS_IEC_RESULT; ipAddr: syssocket.SOCKADDRESS;//Socket address structure for receiving sIpAddress : STRING := '192.168.0.2'; wPort: WORD:= 12346; iecConnectResult : syssocket_interfaces.RTS_IEC_RESULT;//connect paramters sDataRec : STRING[255];//Buffer for received data xiRecBytes : __XINT;//number of bytes received iecRecResult : syssocket_interfaces.RTS_IEC_RESULT;//receive data parameters iecCloseResult : syssocket_interfaces.RTS_IEC_RESULT; END_VAR syssocket.SysSockInetAddr(sIpAddress,ADR(ipAddr.sin_addr)); ipAddr.sin_family := syssocket.SOCKET_AF_INET; ipAddr.sin_port := syssocket.SysSockHtons(wPort); CASE istep OF 1: //create socket IF xStart THEN iecSocketId:= syssocket.SysSockCreate(syssocket.SOCKET_AF_INET,syssocket.SOCKET_DGRAM,syssocket.SOCKET_IPPROTO_IP,ADR(iecCreateResult)); IF iecSocketId = syssocket_interfaces.RTS_INVALID_HANDLE THEN xStart := FALSE; istep := 1; ELSE istep := 2; END_IF END_IF 2: //connect to socket server using setoption iecConnectResult := syssocket.SysSockSetOption(iecSocketId,syssocket.SOCKET_SOL,syssocket.SOCKET_SO_REUSEADDR,ADR(ipAddr),SIZEOF(ipAddr)); istep := 3; 3: //receive data xiRecBytes := syssocket.SysSockRecvFrom(iecSocketId,ADR(sDataRec),SIZEOF(sDataRec),0,ADR(ipAddr),SIZEOF(ipAddr),ADR(iecRecResult)); istep := 4; 4: //close socket iecCloseResult:= syssocket.SysSockClose(iecSocketId); xStart := FALSE; istep := 1; END_CASE
Last updated: 2024-06-03

Post by timvh on Management of a PLC network from a remote station ^{CODESYS Forge talk (Post)}
Maybe the CODESYS HMI is a good solution. https://store.codesys.com/en/codesys-hmi-sl-bundle.html Run this on the remote main control station. In the HMI application you can add the data source manager and to this manager you can add Data sources. A data source has a reference to the PLC you want to connect to and can get access to the variables of the PLC application. You can then use these variables in the visualization of the HMI application.
Last updated: 2023-12-04

Post by lsislsis on Alarms Placeholder ^{CODESYS Forge talk (Post)}
Hello. When i put placeholders at "/etc/codesyscontrol/CODESYSControl.cfg" : [SysFile] FilePath.1=/etc/codesyscontrol/, 3S.dat IecFilePath.1=/proc/, cpuinfo IecFilePath.2=/proc/, iomem PlaceholderFilePath.1=/sys/devices/w1_bus_master1, $OneWire$ PlcLogicPrefix=1 PlaceholderFilePath.2=/data/persistence, $ac_persistence$ PlaceholderFilePath.2.Volatile=1 PlaceholderFilePath.2.View=1 PlaceholderFilePath.3=/data/alarms, $alarms$ PlaceholderFilePath.3.Volatile=1 PlaceholderFilePath.3.View=1 Where "Data" are my USB Flash. I take these attachment errors at run time. What i am doing wrong.
Last updated: 2024-10-15

Post by respl on IFM EXOR Network variable Error ^{CODESYS Forge talk (Post)}
We are connected IFM CR711S to Exor EX710. We are exchanging data using network variables. Both devices are configured on same project so no need to use file source. When tested application it works fine. But after 3 months same application not working. We are able to send data from CR711 to EX710 but data from Ex710 to CR711s works only for one scan when we cold reset CR 711S. Can somebody help to find out error.
Last updated: 2025-03-17

Post by nha451 on EIP Scanner not receiving data from adapter ^{CODESYS Forge talk (Post)}
Hello, I have an EtherNet IP adapter (GoPxL) running with a virtual PLC. I have successfully connected the adapter with green icons next to it. On WireShark I can see the data coming from GoPxL but on CODESYS it shows up as all 0. My firewall is turned off and I have enabled the device to always update variables. I tested my set up with Profinet and I can receive the data. Please let me know if you have any suggestions!
Last updated: 2025-09-12

Post by damian177 on Delete PLC Log ^{CODESYS Forge talk (Post)}
You already know how clear log ? In codesys I am reading twenty Modbus TCP Devices. When several of those doesn't response , the logs is grovs very fast and my PLC hangs.
Last updated: 2023-10-16

Post by bossjosh21 on Codesys Modbus RTU (Modbus_Slave_Com_Port Not Running) ^{CODESYS Forge talk (Post)}
Can someone help me about my problem of my Modbus_Slave_Com_Port Not Running. I am using RevPiConnect 4 and I connected my actuator to the RS485 of my RevPI.
Last updated: 2023-12-05

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 dantheman on Connecting to SoftPLC Only Works By Turning Off Modbus Ethernet Port ^{CODESYS Forge talk (Post)}
It's all good btw, learned that the runtime doesn't isolate the networks that are involved so changing the ethernet subnets away from the Wi-Fi's subnet was all I needed (maybe some config file changes helped, can't say for certain)
Last updated: 2024-08-08

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

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