Setting Up Communications Hardware and Network Communications
7-36
S7-200 Programmable Controller System Manual
A5E00066097-02
7.7 Using the PC/PPI Cable with Other Devices and Freeport
You can use the PC/PPI cable and the Freeport communication functions to
connect the S7-200 CPUs to many devices that are compatible with the RS-232
standard.
There are two different types of PC/PPI cables:
• An isolated PC/PPI cable with an RS-232 port that has 5 DIP switches for
setting baud rate and other configuration items (see Figure 7-27). For technical
specifications about the isolated PC/PPI cable, see Appendix A.
• A non-isolated PC/PPI cable with a RS-232 port that has 4 DIP switches for
setting the baud rate. For technical specifications about the non-isolated
PC/PPI cable, refer to the previous
S7-200 Programmable Controller System
Manual
(model number 6ES7-298-8FA01-8BH0). This non-isolated PC/PPI
cable is no longer available; the isolated PC/PPI cable is the replacement for
the non-isolated cable.
Both PC/PPI cables support baud rates between 600 baud and 38,400 baud. Use
the DIP switches on the housing of the PC/PPI cable to configure the cable for the
correct baud rate. Table 7-8 shows the baud rates and switch positions.
Table 7-8 Baud Rate Switch Selections on the PC/PPI Cable
Baud Rate
Switch (1 = Up)
38400 000
19200 001
9600 010
4800 011
2400 100
1200 101
600 110
The PC/PPI cable is in the transmit mode when data is transmitted from the
RS-232 port to the RS-485 port. The cable is in receive mode when it is idle or is
transmitting data from the RS-485 port to the RS-232 port. The cable changes
from receive to transmit mode immediately when it detects characters on the
RS-232 transmit line. The cable switches back to receive mode when the RS-232
transmit line is in the idle state for a period of time defined as the turnaround time
of the cable. This time depends on the baud rate selection made on the DIP
switches of the cable (see Table 7-9).
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