Mitsubishi Electric WS0-CPU0 Operating Manual page 256

Chapter 9
Figure 237:
Valid breaks when the Start
of first PSDI pulse (PSDI
input Low→High) parameter
is set to After the start of
upstroke
Note
253
Logic programming – Function blocks
PSDI time monitoring
The PSDI time monitoring parameter specifies the required time both for a complete
start sequence and for a cycle start sequence. If the PSDI time monitoring is
exceeded, the PSDI timeout output changes to High. In this case, a complete start
sequence is necessary so that the Enable output can return to High (e.g. in order to
start the press). The PSDI timer starts when the press is stopped at the top dead
center (i.e. the Top input changes from Low to High) and after all other stop conditions
have been fulfilled.
The basic setting for the PSDI time monitoring is 30 s in accordance with the
maximum PSDI time allowed for eccentric presses (defined in EN 692). If the PSDI
time monitoring is set to 0, PSDI time monitoring is disabled.
Start of first PSDI pulse (PSDI input Low→High)
The Start of first PSDI pulse (PSDI input Low→High) parameter determines under
which circumstances a break is regarded as valid.
If the Start of first PSDI pulse (PSDI input Low→High) parameter is set to After the
start of upstroke, a break is valid if the beginning of the break (i.e. falling edge (High
to Low) at the PSDI input) occurs after the rising edge at the Upstroke input, no
matter whether the Top input has changed to High already.
If the Start of first PSDI pulse (PSDI input Low→High) parameter is set to After
Top has been reached, a break is only valid if the beginning of the break (i.e. falling
edge (High to Low) at the PSDI input) occurs after the rising edge at the Top input.
In both cases, the end of the break (i.e. rising edge (Low to High) at the PSDI input)
must occur after the rising edge at the Top input, no matter whether the Top input is
still High or has changed back to Low already.
If the Start of first PSDI pulse (PSDI input Low→High) parameter is set to After the
start of upstroke, upstroke muting must be enabled. Otherwise the Enable output
changes to Low as soon as the PSDI input changes to Low (i.e. at the beginning of the
break).
Upstroke muting and Max. Up-Stroke muting time
Upstroke muting allows bypassing of the PSDI input (e.g. the OSSDs of a safety light
curtain) during the upstroke of the press cycle. Upstroke muting is activated when the
Max. Up-Stroke muting time parameter is set to a value higher than 0. Upstroke
muting is inactive when the Max. Up-Stroke muting time parameter is set to 0.
When upstroke muting is activated ...
 it is imperative that the Upstroke input is connected to a suitable signal. This can
be the Upstroke output e.g. of the Eccentric press contact or of the Universal press
contact function block.
 the PSDI input of the function block is bypassed if the Upstroke input is High and
the Top input remains Low.
The function block does not check the Upstroke input for plausibility. This means that
it is possible to bypass the PSDI input several times if the Upstroke input is activated
several times during a single press cycle.