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IP 240
If you set bit DIGn/9 to "0", a change in the REF bit from 0 to 1 sets the output only when the
actual value enters the track over a track limit.
Note
If DIGn/9 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 output is switched on if the actual value enters one of these tracks over a track
limit at this point.
Resetting the digital outputs
After they have been set, the digital outputs can be reset:
•
by the S5 CPU by setting control bits
•
by the IP 240 in dependence on the actual value when the track is exited.
You can specify the IP's reaction to the exiting of a track for each output separately over bit 8 of
the DIGn parameter (n=1 or 2).
If you set DIGn/8 to "1", the IP 240 automatically resets the digital outputs
•
when the actual value once again exited the track and does not lie within any other track allo-
cated to this output.
It makes no difference whether the actual value exited the track over a track limit, because of
a zero offset, or due to modification of the track limits.
•
when the IP detected a signal acquisition error or range violation.
•
when transfer of the REF control bit initiates a new reference point approach.
•
when the S5 CPU enables actual value-dependent switching of the output by the IP and the
actual value does not lie within a track.
If you set DIGn/8 to "0", the IP 240 does not automatically reset the output.
You can reset the output only by setting control bits DAnF and DAnS in DL17 to "0" and then
transferring the control bits to the IP with control FB 170.
Figure 7-4 shows an example of actual-value dependent setting and resetting of digital outputs.
Note
For the IP 240 to set and reset the digital outputs on the basis of the actual value,
you must enable the outputs over control bits DAnF and DAnS (n=1 or 2).
To do so, set control bit DAnF to "0" and DAnS to "1" in DL17, then transfer the
control bits to the IP 240 by invoking control FB 170 and initializing it for function 2
"Write control bits".
EWA 4NEB 811 6120-02a
Position Decoding
7-7
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