Service manual

Chapter 7 Upgrades and Troubleshooting 70
Cyclades-TS
Installation & Service Manual
on the screen (which also occurs if the loop-back connector is removed), the port is not functioning correctly.
A second method that can be used to test the port is to connect it to a modem with a straight cable. Begin the
test and type “at”. The modem should respond with “OK”, which will appear on the screen. Other commands
can be sent to the modem or to any other serial device.
Test Signals Manually
This test confirms that signals are being sent and received on the selected port. Neither the loop-back connector
nor the cross cable are necessary. Enter the number of the port to be tested and begin the test.
State DTR DCD DSR RTS CTS
ON X X
↓
↓
OFF X X X
First, type Ctrl-D to see the X in the DTR column move position, then type Ctrl-R to see the X in the RTS column
change position. If each of the Xs moves in response to its command, the signals are being sent.
Another method to test the signals is to use a loop-back connector. Enter the number of the port with the loop-
back connector and start the test. In this case, when Ctrl-D is typed, the Xs in the first three columns will move
as shown below.
State DTR DCD DSR RTS CTS
ON X X X X X
↓ ↓ ↓ ↓ ↓
OFF