Hardware Manual

Saia-Burgess Controls AG

Hardware Manual PCD 1 / PCD 2 Series│Document 26 / 737│Edition EN 15│2008-07-22

Appendix A

A

A-2

Definitions of serial interfaces

A.2 Definitions of serial interfaces

A.2.1 RS 232

Designation of signal lines:

Data lines

TXD Transmit data

RXD Receive data

Signal and

response circuits

RTS Request to send

CTS Clear to send

DTR Data terminal ready

DSR Data set ready

RI Ring indicator

DCD Data carrier detect

Signals to RS 232

Signal type Logical state Required value Nominal value

Data signal 0 (space)

1 (mark)

+3 V to +15 V

-15 V to -3 V

+7 V

-7 V

Control /

message signal

0 (off)

1 (on)

-15 V to -3 V

+3 V to +15 V

-7 V

+7 V

The idle state of the data signals = “mark”

of the control and message signals = “off”