Siemens SIMATIC S5 Equipment Manual page 161

Programming Instructions
Software synchronization (SS)
Hardware synchronization (SH)
Parametrize the working data block as shown below.
DW n
Track number
DW n+l
DW n+2
DW n+3
Track identifier bits, channel
DW n+4
Track identifier bits, channel 2
DW n+5
Assigned
DW n+6
O or 255
DW n+7
*) This parameter is used for PLCS S5–150U/S and S5–155U in 150U mode during interrupt
processing (see section 9.4.8).
Supply data word DL n+l with the value 32 (33) to synchronize channel 1 (2).
The data block number of the user data block (DR n+l) must be the same data block number
used also during startup in connection with function block FB 156.
When the "SH" command is used, the NV values are transferred without the SS bit; this is required
for hardware synchronization with preliminary contact and zero mark (see operating instructions).
When the "SS" command is used, the NV values are transferred with the SS bit; this provides a
software synchronization of the counters. Synchronization should only be used for incremental
encoders.
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SS or SH
User DB
I
ST parameter
Alarm bit O to 7
R 02/92
Input
KS
Input
Unaffected
Unaffected
KM output
KM output
KM Output of control bits
Input *)
KY