Manual

MAN0964-01-EN CH.5
June 29, 2012 Page 25 of 122
CHAPTER 5: SERIAL COMMUNICATIONS
5.1 Overview
All XL4 OCS models provide two serial ports, which are implemented with single 8-pin modular RJ45
connectors, and are labeled MJ1 and MJ2. The MJ1 serial port is RS-232 while the MJ2 port is RS-485.
MJ1 defaults to OCS programming by connecting it to the COM port of a PC running Cscape. In addition,
both MJ1 and MJ2 can be used for application-specific communication, using a variety of standard data
exchange protocols.
5.2 Port Descriptions
The MJ1 serial port contains a RS-232 interface with RTS/CTS handshaking.
The MJ2 serial port contains half-duplex RS-485 interface with no handshaking. The MJ2 RS-485
interface provides switchable termination and bias resistors internally.
5.3 Wiring and Dip Switches
5.4 RS-485 Termination
Proper RS-485 termination minimizes reflections and improves reliability.
The 485 serial port allows an internal RS-485 termination resistor to be placed across pins 1 and 2 by DIP
Switch Setting.
Only the two devices physically located at the endpoints of the RS-485 network should be terminated.
5.5 RS-485 Biasing
RS-485 biasing passively asserts a line-idle state when no device is actively transmitting, which is useful
for multi-drop RS-485 networking.
Pin
Name
Function
Default
1
RS-485 Termination
ON = Terminated
OFF
2
Spare
Always Off
OFF
3
Factory Use
Always Off
OFF
Pin
MJ1 Pins
MJ2 Pins
Signal
Direction
Signal
Direction
8
TXD
OUT
-
-
7
RXD
IN
-
-
6
0 V
Ground
0 V
Ground
5
+5V@60mA
OUT
+5V@60mA
OUT
4
RTS
OUT
-
-
3
CTS
IN
-
-
2
-
-
RX- / TX-
IN / OUT
1
-
-
RX+ / TX+
IN / OUT
MJ1/2 Serial Ports
MJ1: RS-232 w/Full
Handshaking
MJ2: RS-485 Half-Duplex
Two Serial Ports on One Modular Jack (8posn)
!
1"
!
8"
!
1 2 3
ON
DIP Switches
001XLE037-R1