Brother DP-550CJ, Service Manual

Page: 114 / 194

REPAIR
SERVICE MANUAL
Troubleshooting
3-51
2 Upper digit = B
An error has occurred in the DTR
→
DSR test executed whie the terminal is
open.
The lower digit expresses the status by bits.
•
Bit 0 = 0: DSR = HIGH when DTR = LOW
Bit 0 = 1: DSR = LOW when DTR = LOW (error)
•
Bit 1 = 0: DSR = HIGH when DTR = HIGH
Bit 0 =
1: DSR = LOW when DTR = HIGH (error)
3 Upper digit = C
An error has occurred in the TXD
→
RXD test executed while the terminal is
open.
•
Lower digit = 0: The data sent to TXD is received at RXD.
•
Lower digit = 1: Data cannot be sent to TXD.
•
Lower digit = 3: Discrepancy between the data sent to TXD and the
data received at RXD
4 Upper digit = 1
An error has occurred in the RTS
→
CTS, RTS
→
CD test executed with the
connector set.
The lower digit expresses the status by bits.
•
Bit 0 = 0: CTS = LOW when RTS = LOW
Bit 0 = 1: CTS = HIGH 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 = LOW when RTS = LOW
Bit 0 = 1: CD = HIGH when RTS = LOW (error)
•
Bit 3 = 0: CD = HIGH when RTS = HIGH
Bit 0 =
1: CD = LOW when RTS = HIGH (error)
5 Upper digit = 2
An error has occurred in the DTR
→
DSR test executed with the connector set.
The lower digit expresses the status by bits.
•
Bit 0 = 0: DSR = LOW when DTR = LOW
Bit 0 =
1: DSR = HIGH when DTR = LOW (error)
•
Bit 1 = 0: DSR = HIGH when DTR = HIGH
Bit 0 = 1: DSR = LOW when DTR = HIGH (error)
6 Upper digit = 3
An error has occurred in the TXD
→
RXD test executed with the connector set.
•
Lower digit = 1: Data cannot be sent to TXD.
•
Lower digit = 2: The data sent to TXD is received at RXD.
•
Lower digit = 3: Discrepancy between the data sent to TXD and the
data received at RXD