The ES-251 is an RS-232-C Isolation and Distribution Amplifier. Three 1 x 8 amplifier circuits allow the incoming signal to be distributed via the 24 outputs. The unit receives RS-232-C and buffers the signal so that each of the 24 outputs can drive a single "user" at a distance of up to 50 feet (per output). All inputs and outputs are via rear mounted terminal DB-9 connectors. The two main purposes of the ES-251 are to:
1) improve the distribution capabilities of RS-232-C
2) provide isolation between users of RS-232-C