Service manual

REPAIR
Troubleshooting
SERVICE MANUAL
3-50
3) Connect the connector for echo-back test and press RETURN. The echo-back test is
executed in the following order:
1 Tests the following :
CTS = LOW and CD = LOW if RTS = LOW
CTS = HIGH and CD = HIGH if RTS = HIGH
2 Tests the following:
DSR = LOW if DTR = LOW
DSR = HIGH if DTR = HIGH
3 Tests that the data* sent to TXD can be received at RXD correctly.
* As the test data, 00(H), FF(H), 55(H), and AA(H) are sent.
4) If the result of test is normal, the following message is printed.
RS-232C TEST OK
(3) Functions
1) If an error is detected during execution of the test, processing ends and the
corresponding error code is printed.
RS-232C TEST ERROR XX
X
X : Error code
Lower digit ..... State of the error in each step.
Upper digit ..... The step where the error occurred.
1 Upper digit = A
An error has occurred in the RTS
→
CTS, RTS
→
CD test executed while the
terminal is open.
The lower digit expresses the status by bits.
•
Bit 0 = 0: CTS = HIGH when RTS = LOW
Bit 0 =
1: CTS = LOW when RTS = LOW (error)
•
Bit 1 = 0: CTS = HIGH when RTS = HIGH
Bit 0 =
1: CTS = LOW when RTS = HIGH (error)
•
Bit 2 = 0: CD = HIGH when RTS = LOW
Bit 0 =
1: CD = LOW when RTS = LOW (error)
•
Bit 3 = 0: CD = HIGH when RTS = HIGH
Bit 0 =
1: CD = LOW when RTS = HIGH (error)