User`s manual

T200 User's Manual SECTION 3: WIRING AND INSTALLATION
PAGE 3-88
3.18.2.3 RS485 Line Termination
RS485 lines must be terminated in 120Ohm resistance, at each end of the cable, between the positive and negative
terminals (RS485+ and RS485-). Figure 3.54 below does not show a 120 Ω resistor at the adaptor end as this is
presumed to be part of the adaptor circuitry.
4 5
RS485+ RS485-
Connector J2
T200
26AWG (0.15mm
2
) Wiring
RS485 Adaptor
GND RS485+ RS485-
4 5
RS485+ RS485-
Connector J3
4 5
RS485+ RS485-
Connector J2
T200
4 5
RS485+ RS485-
Connector J3
Connect Cable Shields to
Metallic D-Sub Shell
Terminate RS485
lines in D-Shell
with 120 Ω
Total Cable
Distance <
1000m
Figure 3.54:- RS485 Wiring and Termination
3.18.2.4 RS485 Cable Maximum Length
The maximum combined length of all RS485 cabling is 1000m. Combined length is the sum of all cable segments,
including the cable from the RS485 adaptor to the first T200, and between subsequent T200's and the next, and so on to
the end of the cable.