Siemens SINAMICS S120 Function Manual page 174

Servo control
4.20 Central probe evaluation
Common features for central measuring with and without handshake
Both measuring procedures have the following points in common:
● Setting the input terminal in p0680.
● Signal source, synchronization signal in p0681.
● Signal source, control word probe p0682.
● Transfer with the communication interface PROFIdrive.
● Synchronizing and monitoring isochronous PROFIdrive
● Prerequisite for measurements is the synchronization between the control and drive.
● Setpoint transfer at start time To and actual value transfer at instant in time Ti in the
PROFIBUS cycle (max. 8 ms).
● Time stamp: Format (drive increments, NC decrements)
● Each valid time stamp in the drive is incremented by 1 in order to make a differentiation
between a valid measuring time zero and an invalid time format. This increment is
removed again by the higher-level control.
● The value "0" in the interface is an invalid time format and indicates that a measured
value is not available.
● Sequencer for the control/status word processing
● Monitoring functions (sign of life)
● Faults
Note
Time-critical data transfer
The status information E_DIGITAL and A_DIGITAL in telegrams 39x are not subject to any
precise time restraints according to the specifications. The transfer of E_DIGITAL and the
output of A_DIGITAL is realized independently of the PROFIBUS cycle with the PROFIdrive
PZD sampling rate according to p2048. Depending on the module, this can be set to
between 1 ms and 16 ms. As a consequence, dead times must be expected for the transfer
of output values and the feedback signal of input values.
Although the probe status word MT_ZSW is identical with the content of E_DIGITAL, it is
however directly transferred in PZDs. As a consequence, for time-critical applications
measuring probes or cams should be used.
174
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
Drive functions