Omron CP1H CPU Operation Manual page 740

Connections to Serial Communications Option Boards
RS-232C and RS-422A/485 Wiring
Recommended RS-232C Wiring Examples
It is recommended that RS-232C cables be connected as described below especially when the Option Board is
used in an environment where it is likely to be subject to electrical noise.
1. Always use shielded twisted-pair cables as communications cables.
UL2464 AWG28x5P IFS-RVV-SB (UL product)
AWG28x5P IFVV-SB (non-UL product)
UL2464-SB (MA) 5Px28AWG (7/0.127) (UL product) CO-MA-VV-SB
5Px28AWG (7/0.127) (non-UL product)
2. Combine signal wires and SG (signal ground) wires in a twisted-pair cable. At the same time, bundle the SG
wires to the connectors on Option Board and the remote device.
3. Connect the shield of the communications cable to the Hood (FG) terminal of the RS-232C connector on
the Option Board. At the same time, ground the ground (GR) terminal of the CPU Unit to 100 Ω or less.
4. A connection example is shown below.
Example: Twisted-pair Cable Connecting SD-SG, RD-SG, RTS-SG, and CTS-SG Terminals in Toolbus Mode
RS-232C
Option Board
Pin Signal
Hood
Note The Hood (FG) is internally connected to the ground terminal (GR) on the CPU Unit. Therefore, FG is
grounded by grounding the ground terminal (GR) on the power supply terminal block. Although there is
conductivity between the Hood (FG) and pin 1 (FG), connect the Hood (FG) to the shield because the
Hood (FG) has smaller contact resistance with the shield than pin 1 (FG), and thus provides better noise
resistance.
Ground to
100 Ω or less.
706
Model
Remote device
Signal
Shield
RS-232C Option Board
Manufacturer
Fujikura Ltd.
Hitachi Cable, Ltd.
Actual Wiring Example
SG signal wires
XM2S-0911-E
Appendix F
Bundle the SG wires.
Aluminum foil