D. Pin Assignments
D-6 February 2001 3160-A2-GB21-90
COM Port Interface
The COM port connects to a PC for front panel emulation, to an ASCII terminal or
printer for alarms, to an async terminal, to a network device (e.g., a router) for
SNMP or Telnet applications, to the LAN Adapter for SNMP or Telnet applications,
or to another DSU/CSU’s AUX port for daisy chain connectivity. (The SNMP LAN
Adapter includes the cable that is needed to attach it to the DSU/CSU.) The
COM port connector is an 8-position keyed modular connector (Ta ble D-6 , C OM
Port Connector). The data signals on this port are referenced to a DTE interface.
The COM port-to-PC cable is shown in Figure D-5, COM Port-to-PC Cable, and
the COM port-to-terminal/printer cable is shown in Figure D-6, COM
Port-to-Terminal/Printer Cable.
NOTE:
For daisy-chaining an AUX port to a COM port, a 25-pin-to-8-pin cable is
required and the appropriate configuration options (Com Use and Aux Use)
must be set to Daisy. Whenever the cable is connected or disconnected, you
should change the Daisy selection to ensure that the correct parameters have
been negotiated for the link layer.
Table D-6. COM Port Connector
Signal Direction Pin Number
DCE Transmit Clock From DSU/CSU 1
DCE Receive Data From DSU/CSU 2
Signal Ground —3
DCE Transmit Data To DSU/CSU 4
DCE Data Terminal Ready To DSU/CSU 5
DCE Carrier Detect From DSU/CSU 6
DCE Request-to-Send To DSU/CSU 7
DCE Receive Clock From DSU/CSU 8