Instruction manual

ControlWave Micro Instruction Manual (CI-ControlWave Micro)

2-28 Installation Revised Jun-2013

Table 2-12. RS-485 Port Connector Pin Assignment

Pin RS-485 Signal RS-485 Description

1 N/A

2 RXD– Receive Data – Input

3 TXD– Transmit Data – Output

4 TXD+ Transmit Data + Output

5 GND/

ISOGND

Ground/Isolated Ground

6 RXD+ Receive Data + Input

7 N/A

8 N/A

9 N/A

Since the RS-485 port is intended for network communications, refer to

Table 2-13 for the appropriate connections for wiring the master, first

slave, and nth slave.

Essentially, the master and the first slave transmit and receive data on

opposite lines; all slaves (from the first to the nth) are paralleled (daisy-

chained) across the same lines. Wire the master node to one end of the

RS-485 cable run using a 24-gauge paired conductor cable (such as a

Belden 9843).

Note: ControlWave Micros support only half-duplex RS-485

networks.

Table 2-13. RS-485 Network Connections

From Master To First Slave To nth Slave

TXD+ RXD+ RXD+

TXD– RXD– RXD–

RXD+ TXD+ TXD+

RXD– TXD– TXD–

GND/ISOGND GND/ISOGND GND/ISOGND

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