Word order of 32 bit ints in OPC server

[Lenvno]

I am testing the use of the NI OPC server in a VB6 app.  THe word order of 32 bit ints in Modbus Ethernet is sometimes reversed for certain instruments.  I have used other OPC servers with configuration to handle the issue but cannot see any way to do this in the NI OPC server.  Does anyone have experience with this problem?

[Gavin F]

Hi Lenvno,

We're looking into this with R&D.

[Justin D]

Hi Lenvno,

You cannot programmatically change the register byte order.  You can select the option on an object by object basis when you are setting up your modbus ethernet objects.  In IA OPC server, select Object->Modify and select the modbus object you want to configure.  On the object configuration page click Advanced.  Here you will see an option for "Modicon 32-bit floating point order (0123 vs. 3210)".  This should be what you are looking for.

Regards,

Justin D

Applications Engineer

National Instruments

Message Edited by Justin D on 01-18-2007 11:29 AM