Mitsubishi Electric SW1DNN-WS0ADR-B, Operating Manual

Page: 216 / 322

Chapter 9
213
Logic programming – Function blocks
A reset button can also be suitable for the override function. Check the requirements
of your application in order to ensure that the safety-relevant logic fulfils the
requirements of the local, regional, national and international regulations.
Table 94 provides information about the Override required output and when Override
is possible under the shown conditions and when not.
Muting
status
At least one
muting sensor
is High
OSSDs of the
ESPE are High
Override
required output
Override possible
0 No 0 No No
0 No 1 No No
0 Yes 0 Pulses at 2 Hz
Yes, if the maximum
permissible number of
override cycles is not
exceeded.
0 Yes 1 No No
1 No 0 No No
1 No 1 No No
1 Yes 0 No No
1 Yes 1 No No
Figure 198 shows an example sequence for Override and Override required .
t
high
has to be equal to or greater than the minimum override pulse time (100 ms or
350 ms), but less than or equal to 3 s. If t
high
is shorter than the minimum override
pulse time or greater than 3 s, the Override input is ignored.
If you use Override, check whether the system is in a safe state!
The Override function is used to activate the safety output (i.e. the Enable output) of
the muting function block although the safety device (e.g. a safety light curtain) signals
that a dangerous state may exist. The
Override input should only be used when the
hazardous area has been checked visually and nobody is in the hazardous area or
has access to the hazardous area while the
Override input is being used.
Ensure that the transitions of the signals for Override fulfill the requirements of
the safety standards and regulations!
In case of a short-circuit to High (to 24 V DC) at a physical input, the evaluated signal
can have a pulse when the signal is reset due to the short-circuit detection. If such a
pulse can result in a dangerous state in the machine, the following points have to be
observed:
 Ensure protected cable laying for the signal line (due to cross-circuiting to other
signal lines).
 No short-circuit detection, i.e. do not reference to test outputs.
Note
Table 94:
Conditions for Override
required and Override
possible
Figure 198:
Logic diagram for Override
and Override required
Note
ATTENTION