Siemens SIMATIC S7 - USS Library; USS Communication Overview; USS Protocol Overview

Libraries
9.5 USS library
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
545
9.5
USS library
9.5.1
USS communication overview
9.5.1.1
USS protocol overview
STEP 7-Micro/WIN SMART instruction libraries make controlling Siemens drives easier by
including pre-configured subroutines and interrupt routines that are specifically designed for
using the USS protocol to communicate with a motor drive. You can control the physical
drive and the read/write drive parameters with the USS instructions.
Siemens designed the USS communications library for use with Siemens general purpose
drives such as the Siemens Micromaster series. Siemens does not intend for the USS
communications library to be used with special purpose drives such as the V90 servo drive.
The control interface of the V90 servo drive is different from that of a general purpose drive.
For this reason, do not use the USS communications library with the V90 servo drive.
You find these instructions in the "Libraries" folder of the STEP 7-Micro/WIN SMART
instruction tree. When you select a USS instruction, one or more associated subroutines and
interrupts are added automatically.
The USS protocol library overview discusses the following subjects:
● Requirements for using the USS protocol (Page 546)
● Calculating the time required for communicating with the drive (Page 547)
Refer to "Using the USS protocol instructions (Page 548)" for a listing of USS protocol
instructions, error codes, and example programs.
Note
Only call the library functi
ons from either the main program or from interrupt routines, but not
both.
Note
For the compact CPU models CPU CR20s, CPU CR30s, CPU CR40s, and CPU CR60s, do
not connect pin 9 of the RS485 cable used for USS communication. The CRs CPU uses pin
9 to dis
able Freeport mode.