Mitsubishi Electric WS0-CPU0 Operating Manual page 213

Logic programming – Function blocks
Direction detection
Direction detection is used when the transported material has to be moved in a
specific direction. The direction depends on the sequence in which the muting sensors
are activated.
If direction detection is disabled, the material to be transported can be moved in both
directions in order to fulfill the muting conditions. In this case it is not relevant which
sensor pair is activated first.
If Forward (A1/A2 first) was selected as the direction, the muting sensor pairs have
to be activated in the sequence (A1/A2) before (B1/B2). Muting is not possible in the
opposite direction. Muting is terminated by a transition from four active sensors to an
inactive sensor pair "B" (no sensor or one sensor active).
If Backward (B1/B2 first) was selected as the direction, the muting sensor pairs have
to be activated in the sequence (B1/B2) before (A1/A2). Muting is not possible in the
forward direction. Muting is terminated by a transition from four active sensors to an
inactive sensor pair "A" (no sensor or one sensor active).
Condition of other sensor pair for muting start
The Condition of other sensor pair for muting start parameter determines when a
valid muting sequence can begin. The Condition of other sensor pair for muting
start can be defined for one of the following conditions:
 Both inputs are clear: All muting sensors have changed to Low together or
individually and the OSSDs of the protective device (e.g. safety light curtain) are
High (i.e. the protective field is clear),
or
 If last muting sensor is active: All muting sensors except the last muting sensor
are Low and the OSSDs of the protective device (e.g. safety light curtain) are High
(i.e. the protective field is clear).
If a higher throughput is required, it can be advantageous to allow the beginning of the
next muting sequence as soon as the transported material has passed the protective
device as well as all muting sensors with the exception of the last one (i.e. If last
muting sensor is active).
Muting end condition
In contrast to the Condition of other sensor pair for muting start, the Muting end
condition determines when a valid muting state ends. You can choose when the
Muting end condition occurs:
 With muting sensor pair: When a muting sensor of the last muting sensor pair
changes to Low (sensor clear),
or
 With ESPE: When the OSSDs of the protective device (e.g. safety light curtain)
indicate that the protective field is no longer violated, i.e., the protective field is clear,
and the OSSDs return to High.
If after the muting end the OSSD input of the ESPE becomes Low (e.g. by a violation
of the protective field of the ESPE) before the next valid muting sequence has begun,
the Enable output of the function block becomes Low. The next muting cycle cannot
begin until the Muting end condition has been fulfilled.
Chapter 9
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