4 SETTINGS AND PROCEDURES PRIOR TO OPERATION

4.4.1 Connecting the RS-232 interface (full-duplex communications)

MELSEC-Q

The following shows the connection precautions and connection examples when using the Q series C24 RS-232 interface for full-duplex communications.

(1)Connection precautions

(a)For further information about the following items, see the explanation in the applicable section in the User's Manual (Application).

Controlling the communication on the Q series C24 side by the external device side using the CD signal of the RS-232 interface.

This is affected by the "RS-232 CD terminal check setting" in "CHn transmission control and others system setting change" screen on GX Configurator-SC.

Performing half-duplex communication using specifications on the external device side (an example of such a connection is shown in this section).

Using modem functions.

(b)The connection cable FG signal and shield are connected as follows.

 

Connection on the Q series C24 side

Notes

Connection cable FG signal

Connect to the Q series C24 connector

Do not short the communication cable FG

signal and the SG signal.

 

housing

 

When the FG signal and the SG signal are

 

Connect to the external device FG terminal

Connection cable shield

connected inside the external device, do not

or the Q series C24 connector housing

connect the FG signal to the Q series C24.

 

 

 

(c)When normal data communication is not obtained due to external noise, perform the wiring as follows:

1)Connect the FG terminals on the external device and the Q series C24 using the shield of the connection cable.

2)Signals other than SG should be connected with SG signals in the twisted pair.

Q series C24

Shield

(External device)

To Connector

 

FG

 

 

housing

 

 

SD

 

RD

RD

 

SD

DSR

 

DTR

DTR

 

DSR

SG

 

SG

POINT

When using an RS-232 to RS-422 converter to connect the external device and the

Q series C24, use a converter that is compatible with the external device and PLC

CPU system configuration (1:1).

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