Special Hardware Requirements: lOne PC/PPI cable lOne converter, 9 -pin female to 25 -pin male lOne converter, serial -to-parallel lOne null modem adapter for swapping lines 2 and 3 (if required) lOne parallel printer One problem might occur. Because the SIMATIC S7-200 and the printer both behave as slaves (data communications equipment, or DCE), the data transfer of each device tries to run in the same direction. This means that both the receive and transmit data lines end up connected to each other (lines 2 and 3). You can avoid this problem by setting up the converter properly or by using an appropriate wiring adapter This example demonstrates how to connect an S7-200 CPU to a printer and send information to the printer by using the Freeport communication mode of the CPU. You can use Freeport mode to transmit data and to receive data. You can use the Freeport mode to define your communication protocol. You select the Freeport protocol in special memory byte SMB30 (for Port 0 of your S7-200 CPU) or SMB130 (for Port 1 of your S7-200 CPU, if your CPU has two ports). You also store the information needed for communication in one of these special memory bytes. After selecting the Freeport mode, you declare the following: lBaud rate lNumber of data bits per character lParity Flow Chart