US 7,321,846 B1
Two-wire process control loop diagnostics
Garrie D. Huisenga, Chaska, Minn. (US); Randy J. Longsdorf, Chaska, Minn. (US); and Donald R. Lattimer, Chaska, Minn. (US)
Assigned to Rosemount Inc., Eden Prairie, Minn. (US)
Filed on Oct. 05, 2006, as Appl. No. 11/543,349.
Int. Cl. G06F 11/00 (2006.01); G06F 11/30 (2006.01)
U.S. Cl. 702—183  [703/188] 25 Claims
OG exemplary drawing
 
1. A diagnostic device for coupling to a two-wire process control loop of an industrial process control or monitoring system, comprises:
digital communication circuitry configured to receive a digital communication signal from the two-wire process control loop, the digital communication signal comprising a digitally modulated analog signal on the two-wire process control loop which is modulated to a plurality of discrete analog signal levels representative of digital values; and
diagnostic circuitry configured to diagnose operation of the two-wire process control loop based upon the digitally modulated analog signal.