Instruction Manual

3-5

IM 04L31A01-17E

Serial Interface

3.3 Terminal Arrangement and Signal Names and

the Connection Procedure of the RS-422/485

Interface

Terminal Arrangement and Signal Names

(Rear panel)

FG SG SDB SDA RDB RDA

FG (Frame Ground) Case ground of the CX.

SG (Signal Ground) Signal ground.

SDB (Send Data B) Send data B (+)

SDA (Send Data A) Send data A (-)

RDB (Received Data B) Receive data B (+)

RDA (Received Data A) Receive data A (-)

Connection Procedure

Cable

There are two types of cables available, the four-wire cable and the two-wire cable (used

only for the Modbus protocol). The cable should meet the following specifications.

Cable Shielded twisted pair cable

3 pairs 24AWG or more (four-wire), 2 pair 24AWG or more (two-wire)

Characteristic impedance 100 Ω

Capacitance 50 pF/m

Cable length Up to 1.2 km*

* The transmission distance of the RS-422/485 interface is not the straight-line distance, but rather

the total length of the (shielded twisted-pair) cable.

Connecting the Cable

As shown in the following figure, attach a crimp-on lug with isolation sleeves for 4 mm screws

to the end of the cable. Keep the exposed section from the end of the shield within 5 cm.

FG SG SDB SDA RDB RDA

Shield potential

Two-wire

Shield

FG SG SDB SDA RDB RDA

Shield potential

Four-wire

Shield

WARNING

To prevent the possibility of electric shock, connect the cables with the power

turned OFF.

Note

• As shown on the next page, connect the RD pin to the SD (TD) pin on the PC (converter) side

and the SD pin to the RD pin on the PC side.

• The two-wire cable can be used only when using the Modbus protocol.