Siemens SIMATIC Box PC 840 Manual page 132

Hardware Information
COM 1 Serial Port (PLC/V.24/Modem) X30*
The serial port (COM 1) on the SIMATIC Box PC 840 has the following pinout:
Figure 7-1 COM 1 Serial Port (Socket Connector)
Pin No.
1
2
3
4
5
6
7
8
9
10 - 17
18
19
20
21
22
23-25
* The line current (TTY) interface is an optional product feature.
7-10
1
14
25
13
Designation Description
- Shield
TxD (D1) Serial transmit data
RxD (D2) Serial receive data
RTS (S2) Request to send
CTS (M2) Clear to send
DSR (M1) Data set ready
GND (E2) Functional ground
(reference potential)
DCD (M5) Data carrier detect
+TTY RxD TTY receive
- Unassigned
+TTY TxD TTY send
+20mA Isolated current source
DTR (S1) Data terminal ready
-TTY TxD TTY send
RI (M3) Incoming call
- Unassigned
Input /Output
-
Output
Input
Output
Input
Input
-
Input
Input
-
Output
-
Output
Output
Input
-
SIMATIC Box PC 840 Manual
A5E00085984-04