Instruction manual

Troubleshooting and Repair
025-9416 129
TST
1
TST
2
TXB
RXB
TXA
RXA
To Main Processor
Board (J8) ⇓
Rear of Model
640 Chassis
⇐
J1 - Serial
Port A
J2 - Serial
Port B
Figure 63. TNPP Interface Board LEDs
Table 23 describes each of the LEDs on the TNPP interface card.
Table 23. Function of TNPP Interface Card LEDs
Label Identifies Operation
TST1 Test 1 Lights to indicate a self-test of the DB-9 serial port J1.
TST2 Test 2 Lights to indicate a self-test of the DB-9 serial port J2.
TXB Transmit B - output Lights to indicate that RS-232 serial data is being transmitted out port
J2.
RXB Receive B - input Lights to indicate that RS-232 serial data is being received on port J2.
TXA Transmit A - output Lights to indicate that RS-232 serial data is being transmitted out port
J1.
RXA Receive A - input Lights to indicate that RS-232 serial data is being received on port J1.
The two test LEDs should light continuously during the boot-up cycle, then flicker and go out
right before the terminal enters operational mode (the front panel “READY” LED is lit).
Testing the TNPP Card
Another way to troubleshoot the TNPP link status is to short the transmit and receive signals
(pins 2 and 3) on the serial interface port together. This effectively sends the pages out and right
back into the TNPP card. Once the pins are connected, the network link should report as “up.” If
this does not produce a cyclical passing of pages, then the interface card itself is malfunctioning.