2-19
SIMATIC PC RI25/45, Technical Description
C79000-G7076-C808-01
The port is designed for RS 232. New transfer modes are used, for example,
for converting a parallel port to an SCSI or to an IDE port. Each mode has an
individual pinout.
Pin
No.
Description
Input/Output
1
Shield
2
Transfer data
(TxD/D1)
Output
3
Receive data
(RxD/D2)
Input
4
Request to send
(RTS/S2)
Output
5
Clear to send
(CTS/M2)
Input
6
Data set ready
(DSR/M1)
Input
7
Functional ground
(GND/E2)
8
Data carrier detect
(DCD/M5)
Input
9
+TTY Receive data
(RxD)
Input
10
–TTY Receive data
(RxD)
Input
11
unassigned
12
unassigned
13
unassigned
14
unassigned
15
unassigned
16
unassigned
17
unassigned
18
+TTY Transfer data
(TxD)
Output
19
Current source, isolated
20
Data terminal ready
(DTR/S1)
Output
21
–TTY Transfer data
(TxD)
Output
22
Incoming call
(RI/M3)
Input
23
unassigned
24
unassigned
25
unassigned
Pin numbers 9, 10, 18, 19, and 21 are unassigned for the different versions of
the motherboard for the SIMATIC PC RI25/45 and must not be used for any
other purpose.
COM1 Port
Motherboard
