Siemens SIMATIC S7-200 System Manual page 238

S7-200 Programmable Controller System Manual
Choosing a PPI Multi-Master Cable or a CP Card for Your Network
As shown in Table 7-8, STEP 7--Micro/WIN supports the RS-232/PPI Multi-Master cable and the
USB/PPI Multi-Master cable as well as several CP cards that allow the programming station (your
computer or SIMATIC programming device) to act as a network master.
For baud rates up to 187.5 kbaud the PPI Multi-Master cables provide the simplest and most
cost-effective connection between STEP 7--Micro/WIN and one S7-200 CPU or an S7-200
network. Two types of PPI Multi-Master cables are available and both can be used for local
connection between STEP 7--Micro/WIN and an S7-200 network.
The USB/PPI Multi-Master cable is a plug and play device that can be used with PCs that support
the USB Version 1.1. It provides isolation between your PC and the S7-200 network while
supporting PPI communication at baud rates up to 187.5 kbaud. There are no switches to set; just
connect the cable, choose the PC/PPI cable as the interface, select PPI protocol, and set the port
to USB in the PC Connection tab. Only one USB/PPI Multi-Master cable can be connected to the
PC at a time for use by STEP 7--Micro/WIN.
The RS-232/PPI Multi-Master cable has eight DIP switches: two of these switches are used to
configure the cable for operation with STEP 7--Micro/WIN.
If you are connecting the cable to the PC, select PPI mode (switch 5 = 1) and Local
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operation (switch 6 = 0).
If you are connecting the cable to a modem, select PPI mode (switch 5 = 1) and Remote
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operation (switch 6 = 1).
The cable provides isolation between your PC and the S7-200 network. Choose the PC/PPI cable
as the interface and select the RS-232 port that you want to use under the PC Connection tab.
Under the PPI tab, select the station address and the network baud rate. You do not need to make
any other selections because protocol selection is automatic with the RS-232/PPI Multi-Master
cable.
Both the USB/PPI and the RS-232/PPI Multi-Master cables have LEDs that provide an indication
of the communication activity with the PC as well as network communication activity.
The Tx LED indicates that the cable is transmitting information to the PC.
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The Rx LED indicates that the cable is receiving information from the PC.
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The PPI LED indicates that the cable is transmitting data on the network. Since the
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Multi-Master cables are token holders, the PPI LED is on continuously once communication
has been initialized by STEP 7--Micro/WIN. The PPI LED is turned off when the connection
with STEP 7--Micro/WIN is closed. The PPI LED will also flash at 1 Hz rate while waiting to
join the network.
The CP cards contain dedicated hardware to assist the programming station in managing a
multi-master network and can support different protocols at several baud rates.
Each CP card provides a single RS-485 port for connection to the network. The CP 5511 PCMCIA
card has an adapter that provides the 9-pin D port. You connect one end of the cable to the
RS-485 port of the card and connect the other end to a programming port connector on your
network.
If you are using a CP card with PPI communications, STEP 7--Micro/WIN will not support two
different applications running on the same CP card at the same time. You must close the other
application before connecting STEP 7--Micro/WIN to the network through the CP card. If you are
using MPI or PROFIBUS communication, multiple STEP 7--Micro/WIN applications are permitted
to communicate over the network at the same time.
Caution
Using a non-isolated RS-485-to-RS-232 converter can damage the RS-232 port of your
computer.
The Siemens RS-232/PPI and USB/PPI Multi-Master cables (order number 6ES7
901--3CB30--0XA0 or 6ES7 901--3DB30--0XA0, respectively) provide electrical isolation
between the RS-485 port on the S7-200 CPU and the RS-232 or USB port that connects to your
computer. If you do not use the Siemens Multi-Master cable, you must provide isolation for the
RS-232 port of your computer.
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