Siemens SIMATIC S7-200 - Modem Settings Required for an 11-Bit Modem; Pin Assignments for a Null Modem Adapter and a 25-Pin to 9-Pin Adapter

Setting Up Communications Hardware and Network Communications
7-26
S7-200 Programmable Controller System Manual
A5E00066097-02
This configuration allows only one master device and supports only the PPI
protocol. In order to communicate through the PPI interface, the S7-200 PLC
requires that the modem use an 11-bit data string. In this mode, the S7-200
controller requires one start bit, eight data bits, one parity bit (even parity), one
stop bit, asynchronous communication, and a transmission speed of 9600/19,200
baud. Many modems are not capable of supporting this data format. The modem
requires the settings listed in Table 7-4.
Figure 7-20 shows the pin assignments for a null modem adapter and a 25-pin to
9-pin Adapter.
Table 7-4 Modem Settings Required for an 11-Bit Modem
Modem
Data Format
in Bits
Transmission
Speed between
Modem and PC
Transmission
Speed on
the Line
Other Features
8 data Ignore DTR signal
11-Bit
1 start
9600 baud
19 200 baud
9600 baud
19 200 baud
No hardware flow
control
11 Bit
1 stop
19,200 baud 19,200 baud
No software flow
tl
1 parity (even)
control
Null Modem Adapter 25-Pin to 9-Pin Adapter
Modem PC/PPI cable
25-pin
25-pin 25-pin 9-pin
2
3
4
5
6
7
8
20
2
3
4
5
6
7
8
20
2
3
4
2
3
7
75
Figure 7-20 Pin Assignments for a Null Modem Adapter and a 25-Pin to 9-Pin Adapter