Instruction Manual

Chapter 3 Specifications

3-31

3.3.3 Interface Specifications

This section describes the specifications of each interface of the ST Series unit.

 Serial Interfaces

 Serial Interface (COM1)

This interface is used to connect an RS-232C serial cable. A D-Sub 9-pin plug connector is used.

• The ST unit’s serial port is not isolated. When the host (PLC) unit is also not

isolated, be sure to connect Pin #5 SG (Signal Ground) terminal to reduce the

risk of damaging the RS-232C/RS-422/RS-485 circuit.

• When connecting an external device to the ST using the SG terminal, be sure to

check that no short-circuit loop is created when you setup the system.

• The same type of connector is used for COM1 and COM2 of the ST. Be careful

not to mistake one for the other. Connecting them incorrectly disables

communication.

• Connecting the RS-232C isolation unit (CA3-ISO232-01) to COM1 enables isolation if

needed.

ST Connector XM2C-0942-502LX <OMRON Co.>

Interfit Bracket #4-40 inch screws are used.

Recommended Cable Connector XM2D-0901 <OMRON Co.>

Recommended Cable Cover XM2S-0913 <OMRON Co.>

Recommended Jack Screw XM2Z-0073 <OMRON Co.>

Arrangement

Pin No.

RS-232C

Signal Name Direction Meaning

1 CD Input Carrier Detect

2 RD(RXD) Input Receive Data

3 SD(TXD) Output Send Data

4 ER(DTR) Output Data Terminal Ready

5 SG - Signal Ground

6 DR(DSR) Input Data Set Ready

7 RS(RTS) Output Request to Send

8 CS(CTS) Input Send Possible

9 CI(RI)/VCC Input/-

Called status display

+5V

±5% Output 0.25A

*1. The RI/VCC selection for Pin #9 is switched via software. The VCC output is not

protected against overcurrent. To prevent damage or a unit malfunction, use

only the rated current.

Shell FG -

Frame Ground

(Common with SG)

(ST unit side)