Chapter 9
257
Logic programming – Function blocks
Unexpected PSDI
The Unexpected PSDI output is High when a valid start sequence has been carried
out and the PSDI input changes from High to Low while no muting is active and no
break is expected. If Unexpected PSDI is High, a valid restart sequence generally has
to be carried out before the Enable output can be set to High.
If the Unexpected PSDI output is High and the Enable output is Low and the PSDI
input is also Low and Restart interlock is set to Without, a restart is possible without
a complete restart sequence. This can also apply during the press upstroke if Restart
interlock is set to Deactivation on upstroke (only for PSDI).
Error states and information on resetting
Diagnostics
outputs
Resetting the error state Remarks
Unexpected
PSDI
If an interruption of the protective field occurs, the PSDI
input generally has to return to High, followed by a valid
restart sequence, in order to reset the error.
If the Unexpected PSDI output is High and the Enable
output is Low and the PSDI input is also Low and
Restart interlock is set to Without or Deactivation on
upstroke (only for PSDI), a restart is possible without
a complete restart sequence.
For PSDI timeout the error is reset by a valid restart
sequence.
The Enable output
changes to Low and
Fault present
changes to High, if
Unexpected PSDI
or PSDI timeout is
High.
PSDI
timeout
Table 113:
Error states and information
on resetting for the N-break
function block
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