Watlow MLS - Manual (Page 56)

44 MLS User’s Guide
Installation
NOTE
Connect the shields to earth ground only at the
computer or other 485 interface. Do not connect
the shield at the MLS. Connect a 200 ohm termi-
nating resistor between RX- and RX+ at the last
MLS (Ju3).
The loop resistance of the transmission line (wire
only, not terminating resistor) must not exceed 200
ohms.
This table shows RS-485 connections.
EIA Standard RS-485 specifies the electrical characteristics of
transmitters and receivers for digital multi-point systems. Watlow-
Anafaze equipment meets RS-485 and RS-422 standards. However, RS-
485 does not specify transmission lines, signaling rates, protocols, etc.
Watlow-Anafaze recommends the following:
• Maximum signaling rate: 9600 baud.
• Twisted shielded pairs for the RS-485 cables.
Line RS-485 Connection Color
TXB RX+Pin 1 Blue/White
TXA RX-Pin 3 Red
RXB TX+Pin 5 Yellow
RXA TX-Pin 2 Black
Ground Pin 4 Green
Shield Shield Pin 6
(Not jumpered internally)
TXA
TXB
RXA
RXB
Ground
Black Box
LD 485A
RX+ #3
RX- #1
TX+ #2
TX- #5
#6
MLS T3A/B
[1] RJ12
RX+ #3
RX- #1
TX+ #2
TX- #5
#6
MLS T3A/B
[n] RJ12
Red
Black
Yellow
Silver
Blue/White
Red
Black
Yellow
Silver
Blue/White
200
Ω