Teledyne 200A Instruction Manual page 181

Teledyne API Model 200A NO Analyzer Instruction Manual, 02246, Rev. F1
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To troubleshoot a modem connection first disconnect the RS-232 cable from the Analyzer and
verify (use a DVM) that you are getting a signal on Pin 2 of the RS232 port on the Analyzer. The
signal will be between -5V and -15V with respect to signal ground (pin 5). If not, there is a
problem with the CPU board or the cable. This is the transmit (TD) signal out of the Analyzer.
This should then be connected to TD input on the modem, normally Pin 2. You may need to
switch the DTE/DCE switch.
Second: Go to the cable connected to the modem/terminal and verify (use a DVM) that you are
getting a –5 V to –15 V signal on Pin 3 of the cable. This pin should be connected to Pin 3 of the
Teledyne API Analyzer.
Third: (for modems) heck that the voltage level on Pin 8 of the Analyzer is between +5V and
+15V. This pin should be connected (through the cable) to Pin 4 of the modem.
Now set the baud rate of the Analyzer to the speed required by the modem and it should work. If
you are still experiencing problems, a cable adapter may be needed. Please contact the factory
for assistance.
9.3.2.2 RS-232 Diagnostic
There are several features of the M200A to make connecting to RS-232 and diagnosing RS-232
faults easier.
There are two LED's on the rear panel Connector Board (01114) which are connected to pin 2
and 3 of the DB-9 connector on the board. If the switch is in the DCE position (default) the red
LED is connected to pin 3 of the DB-9 connector. When data is transmitted by the M200A the
red LED will flicker, indicating data present on this line. When the M200A is running, the LED
will normally be ON, indicating logic low. A one second burst of data can be transmitted over
the port by a command in the DIAGNOSTIC menu. Press SETUP-MORE-DIAG, then scroll to
RS232 OUTPUT. Each time you press ENTR the instrument transmits a 1 sec burst of lower
case "w"'s.
The green LED is connected to pin 2, if the switch is in the default DCE position. This is the pin
on which the M200A receives data. The LED is ON if an outside device is connected. This LED
gets its power from the outside device. When data is being transmitted by the outside device to
the M200A this LED will flicker.
When you are attempting to configure the RS-232 port, if either of the LED's go out when the
cable is connected, that generally means that there is a grounding problem. Switching the DCE-
DTE switch should fix the problem. See the schematic and assembly drawings in the appendix.
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