Saia-Burgess Controls AG
Manual
Manual PCD 1 / PCD 2 Series
│ Document 26
/
737 E
N22 │ 2013-11-26
Appendix
A-2
Definitions of serial interfaces
A
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”
