Measurement Activation Times - Siemens SIMOTION Function Manual

Figure 5-10
The value in LEC is automatically reset during cyclic measurement, und the current measured
values taken over from the measuring equipment to be transmitted to the controller and the
measuring equipment is automatically reactivated for the next cycle.
If the servo cycle clock is scaled down to the TO processing cycle clock, the value must be
fetched in good time; otherwise, it will be overwritten.
Example:
Measuring input processing cycle clock: IPO = 2 ms
Servo/bus cycle clock: 1 ms
⇒ the I/O variable assigned to the LEC must be evaluated in the servo-synchronous user task.
TM17 High Feature
If no edges are measured in a cycle, the TM17 High Feature can measure up to 4 edges in
the following cycle. In this case, the 3rd and, if necessary, 4th edges are buffered (buffering
of up to 2 edges).
In the following cycle, the buffered edges are transferred first, even if new edges have been
acquired; these new edges are buffered again.
You will find further information in chapter
Terminal Modules TM15 / TM17 High Feature Commissioning Manual.
5.2.4.4

Measurement activation times

Various response times (e.g., effects of propagation delays) must be taken into account in the
application for the measuring function, depending on the axis/external encoder connection
(Onboard C2xx, PROFIBUS axis), the drive used (611U, MASTERDRIVES MC, SINAMICS),
and the execution level (IPO/IPO_2, or position control cycle clock).
The measuring process is started with _enableMeasuringInput or
_enableMeasuringInputCyclic in the user program.
The runtime up to the evaluation of the measured edge at the HW input is dependent on the
configuration. In order to detect the measured edge correctly, you must ensure in the user
program that _enableMeasuringInput or _enableMeasuringInputCyclic have been executed
prior to this runtime.
Output Cams and Measuring Inputs
Function Manual, 04/2014
Accessing I/O variables on LEC
5.2 Fundamentals of Measuring Input technology object
System behavior during cyclic measurement in the
Measuring Input TO - Part III
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