Loop back testing for standard RS 232 on a 25 pin connector is as follows:
Transmit to Receive, pins 2 to 3; then connect pins 4&5; and another jumper
among 3 pins: 6,8,20. Since you are looping back, you do not need to use
pin 7, signal ground, nor pin 1 chassis ground. Now was that looping back
only on the Transceiver connector? Of course, this is a standard for either
terminal or modem end of a circuit and should cause the appropriate lights
to illuminate in a modem. (or device acting as a modem).
73, Stuart K5KVH
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