User guide

3. Drive functions
3−58
Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
3 The CMAX accepts the record number and starts positio
ning, i.e. the setpoint curve.
In the PLC input data, the actual record number is set to
the current record and SPOS.MC is reset.
4 The CMAX signalises with the rising edge at SPOS.ACK
that the PLC output data have been accepted and that
the
positioning task is now active.
5 The PLC recognises the acknowledgement SPOS.ACK = 1
in its input data and resets CPOS.START in its output data.
6 CMAX acknowledges the resetting of CPOS.START by re
setting SPOS.ACK.
7 After the PLC has registered SPOS.ACK = 0, it may write
the new setpoint values in its
output data. The CMAX
ignores this until the next start.
Once the record or record chain has been ended,
SPOS.MC is set.
Notes
As soon as the PLC detects the rising edge at SPOS.ACK, it
can assume that MC is valid. From the PLC’s point of view,
the falling edge at MC can occur
at the same time as the
rising edge at ACK. 3 and 4 then cannot be distin
guished.
In the event of faults, the task might not be acknowledged
with SPOS.ACK (depending on the fault). For this reason,
the SCON.FAULT bit must always be evaluated in addition.
Typical causes of error in applications:
 Referencing
has not been carried out.
 Selection of an invalid record number or a record that has
not been initialised.
 The target value lies outside the software end positions.