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Receiving & Installation 3-7MN1853
RS–232 PC Connections
A null modem connection must be made between the LinStep+ and the computer
COM port. This will ensure that the transmit and receive lines are properly
connected. Either a 9 pin or a 25 pin connector can be used at the computer,
Figure 3-8. Maximum recommended length for RS232 cable is 6 ft. (1.8 meter).
Figure 3-8 9 & 25 Pin RS-232 Cable Connections for UL Installations
25 Pin Connector
9 Pin Connector
Pin
Signal
2 RXD
3 TXD
7 GND
Pin
Signal
2 RXD
3 TXD
5 GND
LinStep+
(DCE)
Computer
COM
Port
(DTE)
RXD
TXD
GND
RXD
TXD
GND
RS232/Keypad Connector
Chassis
+5V +5V
If required, RTS, CTS, DSR and DTR may also be
connected for a full null modem connection.
Jumper
9 Pin 25 Pin
RTS to CTS
DSR to DTR
7 to 8
4 to 6
4 to 5
6 to 20
Figure 3-9 9 & 25 Pin RS-232 Cable Connections for CE Installations
Control
(DCE)
Computer
COM
Port
(DTE)
RXD
TXD
GND
RXD
TXD
GND
PE PE
+5V +5V
RS232/Keypad Connector
Note: For CE installations, connect the overall shield at each end of the cable to
PE. The voltage potential between the PE points at each end of the cable
must be Zero Volts.