42
SYNC/ASYNC FIBER OPTIC MODEM
Appendix A. DTE Interface Signal
Assignments
Table A-1. Interface Signal List (Female Connectors),
Pins, and Standard Signal Names
Signal Function
RS-530 DB25
Description
Pin
Circuit
Protective Ground
1
Chassis ground. May be isolated from
Signal Ground (refer to Table 3-1).
Signal Ground
7
AB
Common signal and DC power supply
ground.
Transmitted Data
2
BA(A)
Serial digital data from DTE. The data
transitions must occur on the rising
edge of the transmit clock in sync
applications.
Received Data
3
BB(A)
Serial digital data at the output of the
modem receiver. The data transitions
occur on the rising edge of the transmit
clock in sync applications.
Request to Send
4
CA(A)
A positive level to the Fiber Optic
Modem when data transmission is
desired.
Clear to Send
5
CB(A)
A positive level from the Fiber Optic
13
CB(B)
Modem with delay, after receipt of
Request to Send, and when Fiber Optic
Modem is ready to transmit.
