Connection Method For The Rs-422/485 Interface - Mitsubishi Melsec-L Series User Manual

6.3.3 Connection method for the RS-422/485 interface

SG
FG
FG
Correspondence of the RS-422/485 terminal block and signal position.
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The following explains the connection precautions and examples when using the C24
RS-422/485 interface.
(1) Connection precautions
(a) Refer to Appendix 11 for the bend radius of the connection cable.
(b) Do not install the control lines or communication cables together with the
main circuit lines or power cables.
Keep a distance of 100mm between them.
Failure to do so may result in malfunction due to noise.
(c) The RS-422/485 interface terminal block uses M3 terminal screws.
Use the 1.25-3 solderless terminal. Solderless terminal with insulation sleeve
cannot be used for terminal blocks.
It is recommended to cover the wire connection part of the solderless
terminal with a mark tube or insulation tube.
(d) When connecting the C24 SG and FG signals to the external device,
connect them according to the specifications of the external device.
(e) Ground the shield at only one point.
(f) Connect the shield of the connection cable to the FG terminal on either of the
connected devices.
If normal data communication is not obtained due to external noise even if
wiring is made as explained above, perform wiring as follows:
1) Connect between the FG of both stations with the shield of the
connection cable.
On the external device side, however, follow the instruction manual of
the external device.
2) Connect the (FG) of the C24 side to the FG terminal at the power supply
module of the station which has the C24 installed, or to the FG terminal of
the control panel on which the C24 programmable controller installed.
3) Connect nnA and nnB of each signal in the connection cable as a pair.
C24
SDA
SDA
SDB
SDB
RDA
RDB
SG
RDA
(FG)
RDB
(FG)
6 SETTING AND WIRING
External device
Shield
RDA
RDB
SDA
SDB
SG
FG
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