SHM-B Async

computing equipment for consistency.

3.Wire the SHM-B units back-to-back, eliminating the twisted-pair; see if you still have errors.

•If you do have errors, then test each SHM individually in the following way: loopback one SHM’s Transmit-to-Receive by using two short pieces of wire. Connect that SHM to a dumb terminal and key in characters; look for a good loopback. A good loopback verifies a SHM-B in proper working condition.

•If you don’t have errors, you have verified a problem with the twisted-pair cable.

SYMPTOM: Occasional data errors.

1.The transmission distance/bps data rate capability rate may have been exceeded. Refer to Chapter 1 for information about valid data transmission distances and bps rates.

2.There is a poor quality loop (four-wire circuit). Try using a different four-wire circuit, or rewire the existing circuit.