Hi Chad-TQ
I'm not sure that there is a program we have that simply monitors the bus for requests and responses without writing anything explicitly itself. I know that you would certainly be able to use a counter to keep track of the Modbus Reads and Writes that you perform in your program, if that is what you are trying to do. However, access to all Modbus traffic from any source to any register is information that I do not think you will be able to access.
You could try posting this question to the Industrial Communications Forum linked below:
http://forums.ni.com/t5/Industrial-Communications/bd-p/260
Someone there might have a better idea of a strange workaround that could get you the information you need.
Andrew T.
National Instruments