I need to read a few registers, in modbus format, which contain time/date and also a register with data type word. I know how to read an analog value, for example: Device address.36145F (for phase A current). But I am having an issue reading these values. Your comments are appreciated.

 

>But I am having an issue reading these values.

and the issue is ? ? ?

 

>>But I am having an issue reading these
>values.
>
>and the issue is ? ? ?

The problem is I am reading zeros through an OPC client. Since I am connected remotely to a machine where the OPC server is installed I have no way to verify whether the values are indeed zeros. I am requesting somebody to check these registers for me but it may take a while. On the other hand I want to make sure I am not addressing the registers incorrectly which it may be the case. Thanks.

 

Presumably you have access to the OPC server as well as the OPC client.

Look through the slave's Modbus table for some value that has to be fixed known, like the firmware revision.

Configure the OPC server to get that tag/known value from the slave's Modbus register.

Then configure the OPC client to read that tag/value and confirm that you can read a known value from a known register.

The Modbus addresses could be offset by one because of the register/address offset.

If you get a weird value, configure the OPC server to read the Modbus register +1 and see if that produces the correct value.

 

I use modscan32 for my applications, I has the ability to convert to different formats like integer, binary, 32/64bit swapped/floating point.

http://www.win-tech.com/html/modscan32.htm

hope this helps!