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Position Decoding
Triggering a process interrupt
Every REFn bit can trigger a process interrupt when it goes from 0 to 1 (rising edge). You must
indicate which REFn bits are to trigger interrupts by setting the corresponding bits (0 to 7) in the
PRA1 parameter for configuring FB 169. Each of these bits is allocated to a separate track.
The triggering of interrupts is independent of synchronization of actual-value acquisition.
You may also use bit 8 of the PRA1 parameter to indicate the change of actual value after which
an interrupt is triggered.
If you set PRA1/8 to "1", a change in the REF bit from 0 to 1 will trigger an interrupt when the
actual value
•
enters the track over a track limit,
•
lies within a track following transfer of a zero offset,
•
lies within a track following modification of track limits or
•
lies within a track following termination of a reference point approach.
No interrupt is triggered when the actual value lies within a track following configuring.
If you set PRA1/8 to "0", a change in the REF bit from 0 to 1 triggers an interrupt only when the
actual value enters the track over a track limit.
Note
If PRA 1/8 is set to "0", actual value-dependent triggering of process interrupts is
disabled until the end of the next module firmware cycle in the following cases:
•
for all of the channel's tracks following transfer of a zero offset
and
•
for the modified tracks following the transfer of new track limits.
No interrupt is triggered if the actual value enters one of these tracks over a track
limit at this point.
Setting the digital outputs
Every REFn bit can set one or both of the channel's digital outputs with the 0 1 change. You
must specify this in FB 169 in bits 0 to 7 of the DIG1 parameter for output 1 (D1) and bits 0 to 7 of
the DIG2 parameter for output 2 (D2). Each of these bits is allocated to a track, and each is used to
indicate whether the corresponding REFn bit is to set one or both digital outputs.
The outputs are set without regard to sychronization of actual-value acquisition.
Bit 9 of the DIGn parameter (n=1 or 2) can be used to define the conditions contingent to setting
an output.
If you set DIGn/9 to "1", a change in the REF bit from 0 to 1 sets the output when the actual value
•
enters the track over a track limit,
•
lies within a track following transfer of a zero offset,
•
lies within a track following modification of track limits ,
•
lies within a track following termination of a reference point approach or
•
lies within a track when the IP 240 enables the outputs ( Section 7.2.5).
No output is energized when the actual value lies within a track following configuring.
7-6
IP 240
EWA 4NEB 811 6120-02a
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