compact field point / modbus ethernet swap

[-don.]

We've been asked to look at an existing LabVIEW program that pre-supposed the I/O would be compact fieldpoint.  There are other implementations of the machine that are identical except that instead of NI compact fieldpoint, use alternate hardware and modbus (ethernet) communication to it.  From a hardware perspective, the system is extremely simple in its I/O (a handful of digital outputs and a couple of analog inputs). 

For adding modbus functionality, I've had a look at: http://www.ni.com/swf/demos/us/labview/dscmodbus/  and that works beautifully for creating bound variables - whcih, as far as I can tell, can't be used with the existing FP Write VI's the program currently uses.

What is the best way to support either the generic Modbus or NI compact field point versions of the machine?  Can this be made to be minimally invasive?

If this is addressed elsewhere, I apologize.  I've looked around, but am exceedingly new to LabVIEW, so I could well be overlooking something.

Any guidance/comments greatly appreciated.

[T-REX$]

Hi Don,

Have you seen the Modbus Library for Labview yet?

[-don.]

T-Rex$: Thanks, I had seen that earlier but didn't follow it too deeply.  While prying around, I also found the link I posted and some reference that that was now the *preferred* way to handle Modbus.  

Either way though, I have to cut out all of the "FP Write" (and similar) VI's and replace them w/ Modbus-specific versions?  Though I haven't dug into it much yet, I expect I know how to rip and replace if using the Modbus library.  I've no idea what path to follow if using the Modbus TCP I/O Server from the link I'd posted.

I'd been hoping to do something at the project level to "remap" the I/O and leave the code alone.  I'm now presuming this is impossible? 

I can't be the first one to want to maintain a single source code release that can support both Ethernet Modbus (to Wago) and NI Compact Fieldpoint.  Is there a generally agreed upon "best practice" for this?

Thanks much for any recommendations.