Siemens SIMATIC S7 System Manual page 550

Libraries
9.5 USS library
Table 9- 26
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•
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Refer to the USS protocol execution error codes (Page 560) to compute the time between
status polls and the error conditions that could result from executing the instruction.
Table 9- 27 USS_INIT example program
Network 1
Refer to "Using the USS protocol instructions" (Page 548) for and a listing of USS protocol
instructions and error codes and example programs.
550
Format for the Active drive parameter
D0 (Drive 0 active bit):
– 0 - drive not active
– 1 - drive active
D1 (Drive 1 active bit):
– 0 - drive not active
– 1 - drive active
...
This figure shows the description and format of
the active drive input. Any drive that is marked as
"Active" is automatically polled in the background
to control the drive, collect status, and prevent
serial link time-outs in the drive.
Network 1
LD SM0.1
CALL USS_INIT, 1, 19200, 1, 16#1, M0.0,
VB1
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART