Communication
8.6 RS485
S7-200 SMART
408 System Manual, 09/2015, A5E03822230-AC
Freeport mode is active only when the CPU is in RUN mode. Setting the CPU to STOP
mode halts all Freeport communication, and the communication port then reverts to the PPI
protocol with the settings which were configured in the system block of the CPU.
Table 8- 22 Using Freeport mode
Using Freeport over an
RS232 connection
Example: Using an S7-200 SMART CPU with an
electronic scale that has an RS232 port.
• Connect the two devices using one of the follow-
ing methods:
– RS232/PPI Multi-Master cable connects the
RS232 port on the scale to the RS485 port
on the CPU. (Set the cable to PPI/Freeport
mode, switch 5 = 0.)
– Using the CM01 signal board (SB) (S CPUs
only) which supports RS232 and RS485, you
can connect the RS232 device directly to the
CPU SB RS232 without using the PC/PPI
cable.
• CPU uses Freeport to communicate with the
scale.
• Baud rate can be from 1200 baud to
115.2 kbaud.
• User program defines the protocol.
Using USS protocol
Example: Using an S7-200 SMART CPU with
SIMODRIVE MicroMaster drives.
• STEP 7-Micro/WIN SMART provides a USS
library.
• The CPU is a master, and the drives are slaves.
Creating a user program
that emulates a slave
device on another net-
work
Example: Connecting S7-200 SMART CPUs to a
Modbus network.
• User program in the CPU emulates a Modbus
slave.
• STEP 7-Micro/WIN SMART provides a Modbus
library.
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