Problem reading Float Value from Modbus TCP

General Discussion
1

Hello:
I’ve a Modbus TCP slave which communicates with Ignition SCADA. I am trying to read float values from holding register 10102. The value is read correctly on the gateway tags. I would like to read the float value in my designer project. So, I created a OPC tag with data type float and mapped it to HR10102. But I am receiving some integer value instead of float. Could you please let me know what could be the problem?

Thank you very much in advance,
Shwetha.

2

Step 1. Read the manual. https://docs.inductiveautomation.com:8443/display/DOC79/Modbus+Addressing

You need to have your address as HRF10102, and set the data type to float.

3

Thank you!. That solved the issue

4

I just ran across this thread. I am having the exact same problem as shwethag, except I have used HRF and am still getting a value of zero in Ignition Designer. My exact address is 428893, and so I am using HRF28893. Any help would be appreciated.

5

Usually the problem is one of:

  1. your address is wrong, often off by one
  2. you need to enable the "Swap Words" setting
  3. the value is actually 0

If you can use some 3rd party Modbus software like modscan or modpoll or whatever to see the "right" value then we can see which of those problems it is.

6

Thank you Kevin--I discovered it was #2. as you suggested! Works fine now.