Abstract: A data telemetry system for process control includes a point transponder adapted to receive digitally coded infrared interrogation signals. The transponder includes a first group of positive, intrinsic, negative (PIN) diodes disposed thereon for omnidirectionally detecting interrogation signals and a second group of infrared emitting diodes for generating digitally coded signals responsive to the interrogation signals. The first group and the second group of diodes define a first array of diode nodes, each node including at least one diode from each group. A transceiver includes a generally hemispherical, omnidirectional transmitting and receiving member having a third group of infrared emitting diodes disposed thereon for generating the interrogation signals and a fourth group of PIN diodes for receiving the responsive signals from the transponder. The third and fourth groups define a second array of diode nodes, each node including at least one diode from each other.