A-2 A
PPENDIX
A: P
IN
A
SSIGNMENTS
The table also lists pins assigned for RS-422 functions, when the port is
configured for RS-422 in the firmware. You can use the table as a
reference for cables supplied by 3Com.
CAUTION:
A chassis ground connection between the communications
server and customer equipment is strongly recommended. This
connection minimizes the potential for equipment damage caused by
electrostatic discharges. On models CS/2500 and CS/2600, the chassis
ground connection on serial ports can be made only through the
connector headshells. Do not use pin 1 for this connection, since it is not
connected to the chassis.
Table A-1 RS-232 Serial Port Pin Assignments
Pin
RS-232-
D Name
3Com
Name
Direction
Failsafe
State
Function
1 — — — — Not used
2 BA TXD In Break Transmit Data
3 BB RXD Out — Receive Data
4 CA RTS In True Request to Send
5 CB CTS Out — Clear to Send
6 CC DSR Out — Data Set Ready
7 AB GND — — Signal Ground
8 CF DCD Out Received Line Signal
Detector (Data Carrier
Detect)
9–10 — — — — Not used
11
*
DTE
DSR
DCE
DSR
In — DCE Data Set Ready
12 — — — — Not used
13 — TXD-B In Break RS-422 Transmit Data
14 — TXD-A In Break RS-422 Transmit Data
15 DB TXC Out — Transmit Clock
16 — RXD-A Out — RS-422 Receive Data
17 DD RXC Out — Receive Clock
18 — — — — Not used
19 — RXD-B Out — RS-422 Receive Data
20 CD DTR In False Data Terminal Ready
CS2500BookFile : PinAssignments Page 2 Thursday, December 11, 1997 10:44 AM
