64 Channel Relay Multiplexer The Agilent (now Keysight) 34511 is a Low-Frequency Relay Multiplexer. Performance characteristics include: Form factor module (proprietary interface/bus) Simultaneous channels 64 channel DC/AC voltage max. range: 130 V Measurements/Features include: 2 wire, high and low switching, armature relay type Programmability/Connectivity: User interface proprietary