Running The Example Program; Universal Serial Interface (Uss) Communication - Siemens SIMATIC S7 System Manual

12.3.5.4

Running the example program

To exercise the example program, follow these steps:
1. Download the STEP 7 program to the CPU and ensure that it is in RUN mode.
2. Click the "connect" button on the terminal emulator to apply the configuration changes
3. Type characters at the PC and press Enter.
The terminal emulator sends the characters to the CM 1241 and to the CPU. The CPU
program then echoes the characters back to the terminal emulator.
12.4

Universal serial interface (USS) communication

The USS instructions control the operation of motor drives which support the universal serial
interface (USS) protocol. You can use the USS instructions to communicate with multiple
drives through RS485 connections to CM 1241 RS485 communication modules or a CB
1241 RS485 communication board. Up to three CM 1241 RS485 modules and one CB 1241
RS485 board can be installed in a S7-1200 CPU. Each RS485 port can operate up to
sixteen drives.
The USS protocol uses a master-slave network for communications over a serial bus. The
master uses an address parameter to send a message to a selected slave. A slave itself can
never transmit without first receiving a request to do so. Direct message transfer between
the individual slaves is not possible. USS communication operates in half-duplex mode. The
following USS illustration shows a network diagram for an example drive application.
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
and open a terminal session to the CM 1241.
105BCommunication processor
12.4 Universal serial interface (USS) communication
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