Festo Контроллер позиционирования CPX-CMAX - Manual (Page 93)

3. Drive functions
3−31
Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
When is there reliable data in the parameter values?
The bit 0 of the status word must be set. If the bit is not set,
the information which follows in the structure does not beĆ
long together. It comes from different positioning operations,
or the data was not yet completely initialised.
Once the values have been determined, they remain in the
CMAX until the FCT reads them out. Resetting the bit 0 in the
status word by the FCT allows the CMAX to overwrite the old
values again.
Exception
Depending on the positioning type, the individual values are
filled at different times. In the event of an error or stop, the
information might already be available, but it also might not.
The values are initialised during switch−on and after identifiĆ
cation. Otherwise, the last entry always remains there.
Record chaining
Also, during record chaining, a maximum of one record can
be in the controller at any one time. According to the above−
described handshake, it is a question of time when the FCT
has read out the data and the CMAX can fill the structure with
new data. Without a relatively long waiting time (seconds)
between two consecutive records, the FCT cannot display the
limit values of both records.
The user has no way of controlling the read−out. If the data
from the second record are to be determined, this must be
carried out individually or with a correspondingly long pause.