Using The Rs232/Ppi Multi-Master Cable And Freeport Mode With Rs232 Devices - Siemens SIMATIC S7 System Manual

Communication
8.6 RS485
8.6.6.2

Using the RS232/PPI Multi-Master cable and Freeport mode with RS232 devices

Purpose
You can use the RS232/PPI Multi-Master cable and the Freeport communication functions to
connect the S7-200 SMART CPU to many devices that are compatible with the RS232
standard. The cable must be set to PPI/Freeport mode (switch 5 = 0) for Freeport operation.
Switch 6 selects either Local mode (DCE) (switch 6 = 0), or Remote mode (DTE) (switch
6 = 1). In CRs models only, set switch 7 = 1 to allow Freeport mode.
The RS232/PPI Multi-Master cable is in Transmit mode when data is transmitted from the
RS232 port to the RS485 port. The cable is in Receive mode when it is idle or is transmitting
data from the RS485 port to the RS232 port. The cable changes from Receive to Transmit
mode immediately when it detects characters on the RS232 transmit line.
The CM01 signal board (SB) (S CPUs only) supports both RS232 half-duplex and RS485.
With the CM01 signal board, you can connect an RS232 device directly to the CPU SB
RS232 port without using a RS232/PPI cable.
Baud Rates and turnaround time
The RS232/PPI Multi-Master cable supports baud rates between 1.2 Kbps and 115.2 Kbps.
Use the DIP switches on the housing of the RS232/PPI Multi-Master cable to configure the
cable for the correct baud rate. The following table shows the baud rates (bits per second)
and switch positions.
Table 8- 23
Baud rate
115200
57600
38400
19200
9600
4800
2400
1200
The cable switches back to Receive mode when the RS232 transmit line is in the idle state
for a period of time defined as the turnaround time of the cable. The baud rate selection of
the cable determines the turnaround time, as shown in the table.
468
Turnaround time and settings
Turnaround time Settings (1 = Up)
0.15 ms 110
0.3 ms 111
0.5 ms 000
1.0 ms 001
2.0 ms 010
4.0 ms 011
7.0 ms 100
14.0 ms 101
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART