Azbil C1M - Cables; RS-485 Communication Connections

4-6
Chapter 4. Wiring

RS-485 communication connections
z
If the system includes 3-wire devices only
16
17
18
16
Master station
DA(+)
DA(
+)
DB(
−)
DB(
−)
SG
SG
SG
FG
+
−
Model C1M (slave station)
Model C1M (slave station)
Shielded
cable
Shielded
cable
17
18
Important Terminating resistor
• Connect a terminating resistor (120 Ω, 1/2 W or more recommended) to both
ends of the RS-485 transmission line.
• However, if terminal resistance is not specified for other devices connected
to the same transmission line, do not connect the resistor. If they do specify a
resistor, use the highest resistance value specified, at least 120 Ω.
Handling Precautions
• Do not connect DA (+) to DB (–). Doing so might damage this device.
• Ground only one end of the shielded cable.
• Be sure to connect the signal ground (SG) terminals to each other.
Otherwise, communication may be unreliable.