FISH Callback Events

FISH functions may be called from several places in the PFC program while it is executing. The fish callback is used to manage registering FISH functions with specific callback events; the “Using FISH Callbacks” tutorial discusses this mechanism in detail.

Attaching a FISH function to a callback event causes the FISH function to be executed by PFC, either at a fixed point in the cycle sequence or in response to a specific event. The cycle points can be listed with the program list cycle-sequence command, and a subset of the available events is given here.

One can list the set of FISH functions registered with callback events via the fish list callbacks command.

The fish callback command can be given with the remove keyword to un-register FISH functions. For example:

set fish callback 11.0 remove xxx

removes the association between function xxx and cycle point 11.0. Note that a FISH function may be associated twice (or more) with the same cycle point. In this case, it will be called twice (or more). The remove keyword will remove only one instance of the FISH function.

Note that the whilestepping expression inside a FISH function automatically inserts the FISH function into the cycle sequence at cycle point -1.0.