3 SPECIFICATIONS

3.3 RS-422/485 Interface Specifications

The following shows the RS-422/485 interface specification.

3.3.1 RS-422/485 terminal block specifications

MELSEC-Q

SDA

SDB

RDA

RDB

SG

(FG)

QJ71C24N-R4

The following shows the specifications of the RS-422 connector and RS-422/485 terminal block that connect to an external device.

 

 

 

 

 

SDA

Signal

Signal name

 

Signal direction

 

 

 

 

 

 

SG

 

 

 

abbreviation

C24

 

External

 

 

 

 

 

(FG)

 

 

 

 

SDB

 

 

 

 

 

device

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RDA

SDA

Send data (+)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(FG)

 

 

SDB

Send data (–)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RDB

RDA

Receive data (+)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RDB

Receive data (–)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SG

Signal ground

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

QJ71C24N

FG

Frame ground

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FG

Frame ground

 

 

 

 

 

 

 

 

QJ71C24

 

 

 

 

 

 

 

 

 

 

(1) The following describes the control signals.

1) SDA, SDB signals

These are signals to send data from the Q series C24 to the external device.

2) RDA, RDB signals

These are signals for the Q series C24 to receive data from the external device.

(2)The following shows the function block diagrams. (RS-422/485 interface)

1

SDA

Send data

 

+

SDB

 

–

+

RDA

Receive data

 

RDB

 

–

1 The following shows the terminal resistor connection.

Connect the terminal resistor according to Section 4.4.2 or the User's Manual (Hardware) of the Q series C24 used.

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