4 SETTINGS AND PROCEDURES PRIOR TO OPERATION

MELSEC-Q

(c)Terminal resistor must be set (or connected) for the station of both ends on the circuit.

Match the Q series C24 to the specifications of the external device and connect a terminal resistor (packed with the Q series C24) according to this section.

Connect, or set a terminal resistor at the external device according to the instruction manual of the external device.

(The terminal resistor to connect to the Q series C24)

•When communications performed using RS-422, "330 1/4 W" resistor is connected.

•When communications performed using RS-485, "110 1/2 W" resistor is connected.

How to discriminate between the terminating resistors

330 Ω

110 Ω

Orange Orange Brown

Brown Brown Brown

(d)If data cannot be communicated with the external device at all, the polarity of the external device could be wrong and should be checked again. If the polarities of the Q series C24 and the external device do not match, reverse the polarity of each signal on either device side and connect the devices with the cable; this may enable the data to be communicated.

POINT

(1)For terminal resistor setting/connection described in this section, when the RS- 232 to RS-422 converters or similar device is used at the external device at both ends of the circuit, a terminal resistor must be set, or connected, at the converter.

(2)When using the RS-232C to RS-422 converters to connect the external devices and the Q series C24, use a converter that is compatible with the external device and PLC CPU system configuration (1:1, 1:n, m:n).

(3)Device connected to the Q series C24 RS-422/485 interface must be standardized as RS-422 or RS-485, including 1:n and m:n connections.

(2)Connection examples

(a) External device and Q series C24 with 1:1 system configuration

 

 

 

 

 

Q series C24

 

 

 

 

 

 

 

 

 

 

 

 

 

External device

Terminal

 

 

 

 

 

Signal name

 

 

 

 

 

 

 

 

 

 

 

 

 

Signal name

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

resistor

 

 

 

 

 

SDA

 

 

 

 

 

 

 

 

 

 

 

 

 

RDA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Terminal

 

 

 

SDB

 

 

 

 

 

 

 

 

 

 

 

 

 

RDB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

resistor

 

 

 

 

RDA

 

 

 

 

 

 

 

 

 

 

 

 

 

SDA

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RDB

 

 

 

 

 

 

 

 

 

 

 

 

 

SDB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SG

 

 

 

 

 

 

 

 

 

 

 

 

 

RSA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FG

 

 

 

 

 

 

 

 

 

 

 

 

 

RSB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FG

 

 

 

 

 

 

 

 

 

 

 

 

 

CSA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CSB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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