4-7
Chapter 4. Wiring
z
If the system includes 5-wire devices only
16
17
18
16
SG
SG
SG
FG
17
18
Shielded
cable
Shielded
cable
Master station
Model C1M (slave station)
Model C1M (slave station)
+
−
+
−
DA(+)
DA(
+)
DB(
−)
DB(
−)
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 short DA (+) and 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.
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