Grounding - Mitsubishi Electric MELSEC iQ-F FX5 User Manual

Two-pair wiring
Master
built-in RS-485 port
FX5-485-BD
FX5-485ADP
SDA
(TXD+)
SDB
*2
(TXD-)
RDA
(RXD+)
RDB
*2
(RXD-)
Termination
resistor:
330 
SG
2
*1 Make sure to perform Class-D grounding on the shield of the twisted pair cable to be connected.
*2 Make sure to provide a termination resistor at each end of a line. Set the selector switch to 330  when the termination resistor is built
in.
5.4

Grounding

Grounding should be performed as stated below.
• The grounding should be class D and the resistance should be 100  or less.
• Independent grounding should be performed for best results. When independent grounding cannot be performed, perform
"shared grounding" as shown in the following figure
For details, refer to User's Manual (Hardware) of the CPU module used.
Other
PLC
equipment
Independent grounding
(Best condition)
• The grounding wire size should be AWG 14 (2 mm
• The grounding point should be close to the PLC, and all grounding wires should be as short as possible.
5 WIRING
26
5.4 Grounding
Slave
built-in RS-485 port
FX5-485-BD
FX5-485ADP
SDA
(TXD+)
SDB
(TXD-)
RDA
(RXD+)
RDB
(RXD-)
SG
Class-D grounding
(resistance: 100  or less)
*1
Other
PLC
equipment
Shared grounding
(Good condition)
Slave
built-in RS-485 port
FX5-485-BD
FX5-485ADP
SDA
(TXD+)
SDB
(TXD-)
RDA
(RXD+)
RDB
(RXD-)
SG
Class-D grounding
(resistance: 100  or less)
Other
PLC
equipment
Common grounding
(Not allowed)
2
) or larger.
Slave
built-in RS-485 port
FX5-485-BD
FX5-485ADP
Class-D grounding
(resistance: 100  or less)
*1
SDA
(TXD+)
*2
SDB
(TXD-)
RDA
(RXD+)
*2
RDB
(RXD-)
Termination
resistor:
330 
SG
2
*1