Omron V720 Series Operation Manual page 56

Connection of RS-485 Interface (V720-CD2D)
Connection Examples
1-to-N Connection
Host device
with
terminating
resistance
Terminating
resistance enabled
with SW3-7
Example 1
Sync cable
RS-485 interface cable
4-20
Use a shielded cable for connection to the RS-485 interface. Connect the
shield line to the ground terminal.
Total distance: 300 m max.
Terminating
resistance disabled
with SW3-7
Total distance: 300 m max.
Terminating
resistance disabled
with SW3-7
Note When not using the recommended cable, wire a sync cable alongside the
RS-485 interface cable. Even if a sync cable is wired in parallel with the RS-
485 cable, if it is wired as in examples 2 and 3 below, noise resistance will be
reduced.
Noise
source
Noise sources: Other devices, power lines, AC adapters, etc.
Terminating Terminating
resistance disabled resistance disabled
with SW3-7 with SW3-7
Terminating
resistance disabled
with SW3-7
Host device
without
terminating
resistance
Example 2
Sync cable
Noise
source
RS-485 interface cable
Section 4-7
Terminating
resistance enabled
with SW3-7
Terminating
resistance enabled
with SW3-7
Example 3
Sync cable
Noise
source
RS-485 interface cable