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Connections to Serial Communications Option Boards Appendix F
Recommended RS-422A/485 Wiring Examples
Use the following wiring methods for RS-422A/485 to maintain transmission quality.
1. Always use shielded twisted-pair cables as communications cables.
2. Connect the shield of the communications cable to the FG terminal on the RS-422A/485 Option Board. At
the same time, ground the ground (GR) terminal of the CPU Unit to 100 Ω or less.
Note Always ground the shield only at the RS-422A/485 Option Board end. Grounding both ends of the shield
may damage the device due to the potential difference between the ground terminals.
Connection examples are shown below.
• 2-Wire Connections
• 4-Wire Connections
• Using a B500-AL001-E Link Adapter
Model Manufacturer
CO-HC-ESV-3Px7/0.2 Hirakawa Hewtech Corp.
CP1H CPU Unit
Option Board
Remote device
Shield
Pin
Signal
Signal
A (−)
B (+)
CP1H CPU Unit
Option Board
Remote device
Shield
Pin
Signal
Signal
CP1H CPU Unit
Option Board
Remote devic
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