Siemens SINUMERIK 840C Installation Instructions Manual page 1075

12 Functional Descriptions
12.29.1 Functional description
MA=No. of measured values
The number of measured values indicates the number of measurements to be recorded for a
complete measuring sequence. The required number of R parameters per measuring axis is
derived from the number of measured values:
Required R parameters per measuring axis = number of measured values +1 (see also
MS = Start parameter)
Measured values:
The measured values refer to the respective axis-specific position control resolution of the
assigned measuring axis with regards to their unit.
Linear axes:
For linear axes, the absolute actual value of the axis is stored as a measured value in the R
parameters.
Rotary axes:
For rotary axes, the absolute actual value of modulo 360 degrees is stored as measured value
in the R parameters.
Measuring cut off frequency:
One measured value can be recorded for every position controller cycle (in [ms]). The inverse
value of the position controller cycle (in [kHz])is therefore the limit frequency which still
ensures a safe measured value recording.
Measured value buffer:
Since the recording of measured values is executed in the position controller cycle and since
measured value data can only be transferred to the R parameters in the interpolation cycle, it
is therefore necessary for each measuring axis to have its own measured value buffer
available (MD 6200*, see the functional description: flexible memory management). The
number of measured value memory locations per measuring axis should be at least the same
as the ratio of interpolation cycle to position controller cycle.
Example:
Interpolation cycle =8 ms
Position controller cycle =2 ms
No. of meas. value memory locations per meas. axis=
Repeated measuring
Since measuring with G722 is carried out parallel to other part program processing (traversing
blocks) the situation could arise that further measuring with G720, G721 or G722 is requested
before the measuring initiated by the G722 block has ended. Differentiate between the
following two cases.
Case 1: An axis already programmed in the G722 block is reprogrammed. The measuring
initiated in the G722 block for the axis in question is then interrupted without error
message. The axis will become measuring axis within the new measuring block.
Case 2: An axis not yet programmed in the G722 block is programmed. The measuring
process initiated in the G722 block continues irrespectively.
For detailed information about programming, please refer to the
documentation "840C Programming Guide".
12–300
Interpol. cycle [ms]
Pos. contr. cycle [ms]
© Siemens AG 1992 All Rights Reserved
01.99
8 ms
=4
=
2 ms
6FC5197- AA50
SINUMERIK 840C (IA)