Emerson ControlWave EFM 3808 Instruction Manual page 34

ControlWave Express Instruction Manual (CI-ControlWave Express)
2-20
Table 2-10. RS-485 Network Connections
From Master
TXD+
TXD–
RXD+
RXD–
GND
To ensure that the "Receive Data" lines are in a proper state during
inactive transmission periods, you must maintain certain bias voltage
levels at the master and most distant slave units (end nodes). These end
nodes also require the insertion of 100Ω terminating resistors to
properly balance the network.
You must also configure switches at each node to establish proper
network performance. Accomplish this by configuring switches listed so
that the 100Ω termination resistors and biasing networks are installed at
the end nodes and are removed at all other nodes on the network. You
enable receiver biasing and termination (as well as 2-wire or 4-wire
selection) using an 8-position DIP switch located on the CPU/System
Controller board. See Table 2-3 for more information.
Installation
To First Slave
RXD+
RXD–
TXD+
TXD–
GND
To nth Slave
RXD+
RXD–
TXD+
TXD–
GND
Revised Mar-2011