GE IC687BEM731 VME Single Slot Bus Controller
Serial Cable Lengths and Shielding
The connection from a CPU serial port COM1 to the serial
port on a computer or other serial device requires a serial
cable. This connection can be made with the IC200CBL001
cable kit or you can build cables to fit the needs of your
particular application. See the PACSystems CPU Reference
Manual, GFK-2222 for more information on serial
communications, cables, and converters.
Maximum cable lengths (the total length from the CPU to the
last device attached to the serial cable) are:
■ Port 1 (RS-232) – 15 meters (50 ft.), shielded cable
optional
■ Port 2 (RS-485) – 1200 meters (4000 ft.), shielded cable
required
■ Station Manager (RS-232) – 15 meters (50 ft.), shielded
cable optional
Port 1
Port 1 (COM 1), the lower left port, is RS-232 compatible
and is optocoupler isolated. It has a 9-pin, female, D-sub
connector with a standard pin out. This is a DCE (data
communications equipment) port that allows a simple
straight-through cable to connect with a standard AT-style
RS-232 port.
The Port 1 indicator provides the status of serial port activity.
Port 1 RS-232 Signals
Pin
Number
Signal
Name Description
1* NC No Connection
2 TXD Transmit Data
3 RXD Receive Data
4 DSR Data Set Ready
5 0V Signal Ground
6 DTR Data Terminal Ready
7 CTS Clear To Send
8 RTS Request to Send
9 NC No Connection
* Pin 1 is at the bottom right of the connector as viewed from the
front of the module.
Port 2
Port 2 (COM 2), the top serial port, is RS-485 compatible
and is optocoupler isolated. Port 2 has a 15-pin, female D sub connector. This port does not support the RS-485 to RS-
232 adapter (IC690ACC901). This is a DCE port.
The Port 2 indicator provides the status of serial port activity.

Port 2 RS-485 Signals
Pin
No.
Signal
Name Description
1* Shield Cable Shield
2 NC No Connection
3 NC No Connection
4 NC No Connection
5 NC No Connection
6 RTS(A) Differential Request to Send
7 0V Signal Ground
8 CTS(B‘) Differential Clear To Send
9** RT Resistor Termination
10** RD(A‘) Differential Receive Data
11 RD(B‘) Differential Receive Data
12 SD(A) Differential Send Data
13 SD(B) Differential Send Data
14 RTS(B) Differential Request To Send
15 CTS(A’) Differential Clear To Send
* Pin 1 is at the bottom right of the connector as viewed from the
front of the module.
** Termination resistance for the RD A’ signal should be
connected on units at the end of the line. To make this
termination, connect a jumper between pins 9 and 10 inside the
15-pin D-shell.
Station Manager Port
The station manager port, labeled STA MGR, is RS-232
compatible, DCE, and isolated. It has a 9-pin, female, Dconnector that accepts a standard straight-through cable
(such as IC200CBL001) to connect with a standard AT-style
RS-232 port. This port contains full use of the standard
RS-232 signals for future use with point-to-point protocol.
Station Manager RS-232 Signals
Pin
Number
Signal
Name Description
1* DCD Data Carrier Detect
2 TXD Transmit Data
3 RXD Receive Data
4 DSR Data Set Ready
5 0V Signal Ground
6 DTR Data Terminal Ready
7 CTS Clear To Send
8 RTS Request to Send
9 RI Ring Indicator
* Pin 1 is at the bottom right of the connector as viewed from the
front of the module.