Festo 1971599, Manual

Page: 51 / 150

1. System overview CPX-FVDA-P2
1-21
Festo P.BE-CPX-FVDA-P2-EN en 1209NH English
The detection of a short circuit is not possible in the passiv-
ated status. Therefore, the short circuit is reported up to ac-
knowledgment.
Automatic acknowledgment is possible by holding the ac-
knowledgment bit permanently at “1”. In case of short circuit,
reentry is delayed.
In case of acknowledgment despite the presence of an error,
the output channel is automatically passivated again within
the detection time. If automatic acknowledgment is not de-
sired, the user program must ensure that the F-Host takes the
acknowledgment back again.
Data direction The PROFIsafe protocol in the supported version does not
have an adequate marking of the transmission direction of a
telegram. As a result, it may occur that a telegram from the
F-Host is returned to it and incorrectly interpreted there.
This case is extremely rare and occurs only in the case of
malfunction of a non-reliable slave in the “black channel”.
For reliable avoidance of this exception:
•
Make sure that (in the F-Host) bit 4 of byte 1 of the input
image of the F-user data is regularly checked for “1”.
•
Also make sure that, if a “0” is read in, the relevant mod-
ule in the controller is immediately passivated.