1. An interface module for use in a process control system including a Fieldbus process control network having a plurality of Fieldbus field devices and a Modbus process control network having a plurality of Modbus field devices, the interface module operatively connecting the Fieldbus process control network to the Modbus process control network and being adapted to facilitate the exchange of process control information between the Fieldbus process control network and the Modbus process control network, the interface module comprising: a Fieldbus I/O module operatively coupled to the Fieldbus process control network and being adapted to transmit and receive Fieldbus protocol messages on the Fieldbus process control network; a Modbus I/O module operatively coupled to the Modbus process control network and being adapted to transmit and receive Modbus protocol messages on the Modbus process control network; and a controller operatively coupled to the Fieldbus I/O module and the Modbus I/O module, the controller comprising a processor and a memory operatively coupled to the processor, the controller being programmed to store in the memory a register map database wherein at least one Fieldbus process control parameter of the Fieldbus process control network is associated with a Modbus register number of the Modbus process control network, the controller being programmed to cause the Fieldbus I/O module to request a current value of the at least one Fieldbus process control parameter from a corresponding one of the Fieldbus field devices, the controller being programmed to store the current value of the at least one Fieldbus process control parameter in the register map database with the associated Modbus register number, and the controller being programmed to cause the Modbus I/O module to transmit a response message to one of the Modbus field devices with the current value of the at least one Fieldbus process control parameter and the associated Modbus register number in response to receiving a request message from the one of the Modbus field devices at the Modbus I/O module for the current value of the associated Modbus register number.