Measuring Function; Use Cases - Siemens SIMATIC S7-300 Product Information

Expert Functions

5.6 Measuring Function

5.6 Measuring Function
5.6.1

Use Cases

Measuring function
The "Measuring" function can be used to determine the actual position of an axis at any time.
A possible application is, for example, the acquisition of a registration mark in order to
subsequently synchronize the axis to this mark.
MC_MeasuringInput function block
Depending on the processing level (position-control or interpolator cycle),
different response times must be used when the Measuring function is called.
The MC_MeasuringInput function block is called to control the measuring in the S7 user
program. The type of the activation of Measuring function can be configured on the block.
The following functions can be called:
● immediately (without measuring window / measuring range)
● Within a position-dependent measuring window
Measuring without measuring window
The measuring input will be activated immediately. A configuration-dependent time elapses
before the measuring edge at the hardware input is evaluated.
To reliably detect the measuring edge, the run time must be compensated.
Measuring with measuring window
The request is initially only registered in the system. The measuring input is only activated
when the axis is at the beginning of the measuring window.
A configuration-dependent time elapses after reaching the start position of the measuring
window on the axis (mechanical) until the measuring edge at the hardware input is
evaluated. To ensure that the measuring input is active when the required start position of
the measuring window on the axis is reached, the run time must be compensated.
Similar considerations apply at the end of the measuring window. It is important that the
measuring input is no longer active when the end of the measuring window on the axis
(mechanical) is passed.
152
StartPosition = EndPosition
StartPosition < > EndPosition
Connection of the SINAMICS S120 to the Technology CPU
Product Information, 09/2011, A5E00480378-04