Jay,
Most folks use an OPC Server, such as Lookout Protocol Drivers (sold under package "IA OPC Servers") to communicate with devices using the Modbus protocol from LabVIEW. The KnowledgeBase below describes this method in detail.
Drivers for Communicating to PLCs, RTUs, and Other Industrial Hardware"As for direct Modbus protocol VIs for LabVIEW - I have never personally used them, but I have seen many Developer Exchange posts in the past where folks have used and recommended them. Simply search this developer exchange for "modbus AND labview" and numberous discussion threads on this topic will be returned.
Regards,
Greg
Caesar
Applications Engineer
National Instruments
