Siemens Simovert Masterdrives Compendium page 769

Technology Option F01
Nesting the
Synchronization
Block
9-78
The virtual master [832] can be calculated on any MASTERDRIVES. Its
output setpoints KK817 and KK816 [832.8] (path and velocity) are
distributed over the SIMOLINK drive interface.
Calling up the synchronization block U953.33
The synchronization block is called up either as a free block or from the
mode manager of the positioning system [802.8]. The differences are
listed in the table below.
a) Calling from the mode manager of the positioning system
The mode selector [MODE_IN]=11 can be used to activate the
synchronization as a "positioning mode" [809.4]. This is the
recommended method for activating synchronization.
You can then change between positioning mode and synchronization
mode. The synchronization block is called up from the mode manager
of the positioning system, and the synchronization is calculated within
the sampling time of the positioning modes set in U953.32. The value
20 must then be entered in parameter U953.33.
The positioning control signals are also used in this process, e.g. start
command [STA] [809.4], and the corresponding checkback signals are
also generated [809]. Following error monitoring is performed with
reference to machine data MD15, in addition to software limit switch
monitoring − for linear synchronization axes − with reference to
MD12/MD13.

The "Synchronization mode" chapter in the Function Description
of manual /1/ contains a detailed description of the
control/checkback signals with timing charts for synchronization
as a positioning mode.
b) Calling synchronization as a free block
If only synchronization [834...839], and not positioning, is required by
the technology functions, it is possible to nest the synchronization like a
free block in a sampling time. In this case, parameter U953.33 must be
set < 20. The value 4 = 16*T0 (= 3.2 ms with a converter frequency of 5
kHz) is the preferred setting. The positioning modes must remain
deactivated in this case with U953.32 = 20.
The use of synchronization as a free block is associated with the
following advantages:
♦ As a result of deactivation of the mode manager, approx.
50 ... 100 μs less calculating time is required as the mode manager
is not activated.
♦ The control sequences in the host machine controller can be
simplified: it is no longer necessary to deal with the positioning
control and status signals shown on sheets [809] and [810].
The disadvantages arise from the different activation methods used for
synchronization and positioning and the absence of the following error
and software limit monitoring (the latter can be useful with linear
synchronization axes).
6SE7087-6QX70 (Version AN)
Compendium Motion Control
08.2012
Siemens AG
SIMOVERT MASTERDRIVES