West Control Solutions N8100 - Manual (Page 48)

1.3.11 RS485 Serial Communications Link
The cable used should be suitable for data transfer at the selected rate (1200,
2400, 4800 or 9600 Baud) over the required distance. Transmitters/receivers
conform to the recommendations in the EIA Standard RS485.
The “A” terminal on the Controller should be connected to the “A” terminal on the
master device; the “B” terminal on the Controller should be connected to the “B”
terminal on the master device. Where several Controllers are connected to one
master port, the master port transceiver in the active state should be capable of
driving a load of 12k Ω per Controller; the master port transceiver in the passive
state must have pull-up/pull-down resistors of sufficiently low impedance to ensure
that it remains in the quiescent state whilst supplying up to ± 100 µ A each to the
Controller transceivers in the high impedance state.
NOTE: The RS485 Serial Communications option and the Dual
Setpoint option are mutually exclusive.
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