Patent ID: 8000841

Claim:
An industrial process transmitter for transmitting a process variable on a two-wire process control loop, the industrial process transmitter comprising: a loop current control coupled to the two-wire process control loop and adapted to control a loop current level on the two-wire process control loop that is related to the process variable; a power supply connection coupled to the loop current control and adapted to provide power to primary circuitry of the process transmitter at a quiescent current level and which is derived from the loop current; a databus configured to couple to secondary circuitry of the industrial process control transmitter; a secondary current control circuit having an input coupled to the power supply and an output coupled to the secondary circuitry, the secondary current control circuit adapted to provide current to the secondary circuitry from the power supply and to limit current delivered to secondary circuitry from the power supply as a function of an adjustable input; and wherein the secondary current control circuitry is adapted to adjust current delivered to the secondary circuitry by a positive and a negative amount during respective positive and negative portions of a signal transmitted using a digital communication protocol.