Chapter
6
Operating Instructions
Laser measurement sensor LD-MRS
86
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SICK AG · Germany · All rights reserved · Subject to change without notice
8012948/ZMQ0/2017-06-09
Commissioning and configuration
6.6.1
Synchronization details
Important
The synchronization frequency must be between 8.5 Hz and 50 Hz.
Frequencies above and beyond these values are not accepted by the LD-MRS.
The precision of the synchronization (i. e. the time difference between synchronization
pulse and the moment of crossing the angle that was specified as SyncAngle) is approx.
±1,000
μ
s for a scanning frequency of 12.5 Hz if no external forces act on the LD-MRS (es-
pecially no angle acceleration).
This is the equivalent of an angular precision of ± 4.5° around the true 0° direction.
For the scanning frequency of 25 Hz and 50 Hz the precision is ± 500
μ
s, equivalent to an
angular precision of ± 4.5° or ± 9°, respectively.
The external synchronization frequency f
sync
can be selected in a range of 8.5 Hz
≤
f
sync
≤
50 Hz and should have a relative precision better than 0.1 % (the better f
sync
, the better the
laser measurement sensor).
Therefore we recommend not to send the synchronization signal from a PC because they
generally have less precise timers. Instead use a designated micro-controller to generate
the synchronization signal.
The external synchronization frequency and the scanning frequency do not need to match.
The external synchronization frequency must be within ± 4 Hz of the scanning frequency f
s-
can
(f
sync
= f
scan
± 4 Hz). The LD-MRS adjusts the scanning frequency to the external syn-
chronization frequency.
When the external synchronization frequency fails, the LD-MRS adjusts its scanning fre-
quency again to the initially specified value.
Fig. 6-3:
Details synchronisation