4.6 Serial Command Communications Connector (CN12)
4.6.4 Wiring Precautions
4-45
4
W
iring and Connecting
4.6.4
Wiring Precautions
•
The maximum total length for RS-422 or RS-485 cable is 50 m. Use the minimum length of
cable that is needed.
•
The INDEXER Module’s communications circuits are not insulated. If communications errors
occur because of noise, use noise suppression methods such as shielded cable or ferrite
cores.
•
When using full-duplex wiring, connect a terminator in the host controller’s reception circuit
and the reception circuit of the last INDEXER Module in the line. The INDEXER Module has a
built-in terminator (120
Ω
) that is connected between the RXD and /RXD pins when the RT
and /RXD pins are shorted.
•
When using half-duplex wiring, connect a terminator at both ends of the communications cable.
The
INDEXER Module has a built-in terminator (120
Ω
) that is connected between the RXD
and /RXD pins when
the RT and /RXD pins are shorted.
•
The INDEXER Module’s transmission circuit is high-impedance when it is not transmitting.
Pull up or pull down the host controller’s reception circuit.