M241 - Modbus TCP - problema reading analog inputs (#300001)

[horvatmiha]

Hello!

I am new at programing PLCs. I am using TM241CE24R PLC with TM3AI4 analog input module. I can successfully read temperature from 4-20 mA sensor. I want to communicate with my PC (SCADA) via Modbus TCP. For testing purposes I am using CAS Modbus Scanner. I can read digital inputs, coils and holding registers successfully. Problem is that I can't read analog inputs (#300001 etc.).  I have nothing defined in GVL list. Is this causing problem? I also don't have any Modbus TCP Slave device in Ethernet_1. But how can be all the other registers read successfully?  Please take a look at screenshots below. Also check Error message from CAS Modbus Scanner. Where is problem? Please help. Thanks in advance!

Edited November 7, 2019 by horvatmiha

[Quant]

Hi, I'm not familar with Somachine.

Your analog input module uses addresses %IW2-%IW5, but you try to read %IW1 (30001). 

[horvatmiha]

This is not problem. And I managed that so I am reading correct address. But this would not produce that kind of error. There is something wrong in program or configuration but I can't figure it out.

[cHud]

As I mentioned in previous topic that you also queried on, just move the analog input value into a %mw and read it from there. Not all software allows you to read directly the digital io or analog io

[horvatmiha]

Yes, it is solution. But the software that I am using (MBE driver v7.48) is able to read directly analog inputs. It works with other PLCs, for example M221 (TM221CE16R). I believe there must be something wrong in configuration of PLC in SoMachine. If anyone has an idea please share it with us.

Thanks in advance!

[saruans]

M241 M251 M258 LMC058:

%M (internal bits) cannot be accessed by Modbus.
But %I (physical inputs) and %Q (physical outputs) can be accessed using function codes from the table below (extracted from SoMachine online help).