Flexy 205 and Idex FC6A


trying to pull some data tags via ModBus from a Idec PLC,
Not sure what the easiest setup is?
Should the Idec act as Modbus server or client, and what should be Flexy be?
Another issue is adddressing…


Hi Lars,

You should check out this documentation to see what works best for your scenario. There are instructions for configuring the addressing as well.


Let me know if you have any questions.



I’ve been succesful talking ModBus to a Horner PLC, Idec not so much.
I was just curious if someone else might have done this before with this brand.


Gotcha, if you are trying to pull tags from the PLC, I would suggest the PLC as the slave device and you can use RS232, or RS4xx for Modbus RTU, or ethernet for Modbus TCP, depending on the specific model of FC6A. I’ll check if anyone here is more familiar with that device particular device.


The PLC is currently set up as a Modbus/Tcp server so maybe that is the problem.
The only other option is Modbus Client, but maybe that is the same as a slave?


The server is the same as the slave basically. If you are using ModbusTCP, and want to poll the PLC, than it’s correct to have it set up as the server. I assume you created some tags to test. Are you seeing any errors in the event logs?

If you want, you can send me a backup with support files and I’ll check the configuration and see if I see something that is off.



Do you mean that it is correct to have the Flexy setup as the server, when I want to pull tags from the PLC?


No, I said the server is the same as the slave and in this case the PLC will be the server. These are the instructions you need to follow :




Looking at your config, you have a Modbus tag set up with the address +408170 which is not a correct address. You will find the correct addresses in the PLC user manual. A typical address of a holding register is going to be 4xxxx.

Make sure you set up the correct settings under Tags > IO Servers > Modbus


Actually, that address is correct, this PLC has the extended address format, and I got it to work with PLC as server and Flexy as slave. I had the wrong slave node no specified.


OK great, I was wondering if you were using the extended addresses, but assumed it was wrong from the error logs.