https://forge.codesys.com/forge/talk/Runtime/thread/8a45c56051/2022-10-12T06:15:15.516000ZRecent posts to Codesys Modbus Comport2022-10-12T06:15:15.516000Z2022-10-12T06:15:15.516000Zhappychappyhttps://forge.codesys.com/u/happychappy/https://forge.codesys.com18fefb6ab47d2428ee61aa99ba68d89f145a14f9

<div class="markdown_content"><ol> <li>Exactly the same hardware setup on Ecockpit.</li> <li>the port is configured as RS485 via the PLC shell</li> <li>So there is a 120ohm resistor at the PLC and a 120 ohm resistor at the busend (between A and B). I also tried adding pull up and pull down resistors, since the wago Engineer advised me to try that since it is mentioned in the Wago manual on page 40.<br/> <a href="https://www.wago.com/wagoweb/documentation/750/eng_manu/coupler_controller/m07508212_xxxxxxxx_0en.pdf" rel="nofollow">https://www.wago.com/wagoweb/documentation/750/eng_manu/coupler_controller/m07508212_xxxxxxxx_0en.pdf</a></li> <li>I am also running shielded cable, and have tried to connect the shield to PE/GND only on the PLC side, then I tried to only connect it to PE/GND at the bus end. I have also tried connecting the shield on both the PLC and the bus end at the same time, but nothing solved the issue.</li> <li>I can also reproduce the issue with a a replacement PLC and replacement slave devices.</li> <li>Like i menntioned, the only way I can get completely rid of the errors is using a TCP to RS485 gateway in between or using Ecockpit</li> </ol></div>

2022-10-11T18:59:14.640000Z2022-10-11T18:59:14.640000Zeschwellingerhttps://forge.codesys.com/u/eschwellinger/https://forge.codesys.combb44199632e36f5bd061f3e4ae3c4da3f782f372

<div class="markdown_content"><p>not really a clue -<br/> if you use the exact same device (plc) and slaves and wiring this works like charm with Ecockpit (or is it a different application other slaves other pfc)<br/> I just want to verify if it is physical problem on wiring or slaves.<br/> For Modbus RTU and CODESYS you need to set RS485 in the plcshell, this is what you have already done?<br/> What about the busend resitors on end of the line (last device)</p></div>

2022-10-11T09:35:40.712000Z2022-10-11T09:35:40.712000Zhappychappyhttps://forge.codesys.com/u/happychappy/https://forge.codesys.com323a13ef5f82969b057892d710b87c253f3e1329

<div class="markdown_content"><p>Brief background:<br/> Hardware: Wago 750-8214<br/> PLC Wago FW: 16-21<br/> Codesys Runtime: V4.4<br/> Modbus RTU</p> <p>I have a issue where I have a number of the same type of modbus slave device connected to my PLC, which is the master of the network. Between 1-10 hours, I would get a CRC or a Timeout Error report from the a random slave device in the device tree on the left hand side inside codesys,</p> <p>When I just use Wago Ecockpit as the runtime on the PLC, I do not experience any modbus issues on the network. </p> <p>The obvious difference between the 2 runtimes is the library that is being used for the communication. Wago has its own Library for modbus communication in e!Cockpit, and in codesys the library that I see being used by the device tree on the left hand side is 3S - Smart Software Solutions GmbH. </p> <p>I have contacted Wago about this problem, and they of course they mentioned if it works on e!Cockpit then it must be a codesys issue.</p> <p>The only way I can get rid off the modbus CRC and timeouts inside codesys, is to configure the modbus communication as TCP, and then use a Modbus TCP to RTU gateway between the PLC and slave devices. This is not what I want to do.</p> <p>Is there any suggestions/recommendations on what I can try to do to get the Modbus RTU stable?</p></div>