I'm looking at the National Instrument Compact FieldPoint/LabviewRT system for an OEM automation project. The system will have about200-400 discrete IO points distributed along the machine in about 4-6 drops. The problem is when I use the NI hardware my budget gets busted beyond all repair. I would like to use a third party remote IO product but can't find any that NI supports with drivers. Is there a developer out there who can write a custom driver to use the serial port and talk to a Modbus RTU net? Or does somebody have any other ideas using off the shelf hardware?