https://forge.codesys.com/u/egr99/2026-04-08T12:17:21ZRecent posts by egr992026-04-08T12:17:21Z2026-04-08T12:17:21Zegr99https://forge.codesys.com/u/egr99/https://forge.codesys.com8e7e0b2c91e54301309e073f2e18107e3e7ac72e

<div class="markdown_content"><p>You're absolutely right. Sorry for that.</p> <p>In the meantime I wrote a Function block to handle the reads and writes to the different attached RTU-devices. <br/> It processes the parameter like (str_Modbus:=(usiSlave:=1, uiFC:=5, uiLEN:=1, uiOFFSET:=0, uiInterval:=500)) and the corresponding output, waits for the response and processes next request in a 5-state procedure. It's working for 2 gateways (stable without errors, although error recovery is included). </p> <p>But nevertheless it should be possible with the Channel definitions of Codesys. Much easier to maintain :) </p></div>

2026-04-05T20:10:38Z2026-04-05T20:10:38Zegr99https://forge.codesys.com/u/egr99/https://forge.codesys.com4eaa402931c0a96ed6656dea0c276a1873f67c52

<div class="markdown_content"><p>Hi there,</p> <p>Read the above description and experienced the same: Reading coil/discrete input/input register/holding register doesn't fill the mapped I/O variable.</p> <p>Any suggestions? </p> <p>Defined (see attachment):<br/> - Ethernet (with parameters according to the used Ethernet adapter of my Windows 11 laptop)<br/> - -Modbus TCP Client<br/> - - -LOGO231 as Modbus TCP Server<br/> - - -WS242 as Modbus TCP Server (WaveShare Modbus TCP &lt;-&gt; RTU converter)<br/> - - - -WS242_01 as Modbus Server, COM port (slave-id 1 RTU)<br/> - - - -WS242_03 idem (slave-id 3 RTU)<br/> - - - -WS242_11 idem (slave-id 11 RTU)</p> <p>Writing coil/holding register works from a mapped I/O variable works fine.</p> <p>Verification of Modbus traffic with WireShark:<br/> QUERY to and the RESPONSE of all slave-ids are correct</p> <p>Status of all defined is CONNECTED, RESPONSE_SUCCESS, RUNNING etc.</p> <p>Request counters increase with expected frequency. Error counter = 0.<br/> (To have all counters works fine I had to change Modbus TCP Client's parameter OptimizationON to FALSE). </p> <p>LOGO231 works fine: values in mapped I/O conform expectation<br/> WS242 without Modbus Server, COM port and<br/> with defined channels (for only 1 slave-id possible) works fine.</p> <p>PLC Settings: <br/> Update I/O while in stop: I see xBusy changing from FALSE to TRUE and vice versa.<br/> Always update variables: Enabled 1</p></div>