ABB TB840A Modulebus Cluster Modem
Description:
TB840A is part of ABB 800xA control system communication module. TB840 ModuleBus Modem is a
fiber optic interface to the OpticalModuleBus. It is used in redundancy configurations where each module is connected to different opticalModuleBus lines, but connected to the same electricalModuleBus.

• 2 fiber optic ports to opticalModuleBus
• ModuleBus (electrical) to the I/OModules
• Supervisoryfunctions of I/OModuleBus and power supply
• Isolated power supplyto I/O modules
• TU840,MTU for redundant TB840/TB840A, dualModuleBus
• TU841,MTU for redundant TB840/TB840A, singleModuleBus
• Input power fused