Getting address errors when trying to access Wago 750 PLC modules

[Dhouston]

Hello all.  First off, I know there are many topics dealing with this kind of issue, but the problem is that links that are given in those topics always come back with a 404 Not Found, so I can't follow what suggestions people have given because I can't get to the pages they link.

So I have a Wago 750-8101 controller with the following modules attached:

750-458 - Thermocouple module

750-1407 - 24V input module

750-1504 - 24V output module

I am trying to use Labview Modbus to read the modules.  For my immediate need, I am trying to read the 458 thermocouple module.  Attached is the program I am using.  The pictures show the error I get as well as the plc addresses for the modules

I have done some other research, and seemed to recall something about using Network Shared Variables to access the modules.

Why am I getting the error when I am using the addresses the plc is giving?

[Martin_Henz]

The wago controller can block a range of modbus addresses. In this case, you'll see the "Illegal Data Adress" error. Have you checked, that the block mode is disabled?

[Dhouston]

Thank you for responding.  I got in contact with Wago and their Application Engineer helped me get things working.  My problem was twofold:  1. I had declared a variable as a type that could not be used for the value I was seeking.  2.  I was reading from the wrong register number.  The engineer made a new variable of the type I could use, then we saw the register this variable was occupying.  I set my program to read from this new register, along with reading the appropriate number of word counts, and I was able to see a value.  I'll have to convert/scale it, but I can say I am successfully reading the controller now.

Your information is news to me, and quite valuable.  I'll check on that as well to ensure I won't have future issues because of it.