Specifications

Crestron SIMPL Windows Software
custom control system you would normally want to handle this internally, thus the
user can simply tap a button and the projector would turn on as expected. Shown
above is a One Shot symbol that is triggered off a button press and generates a 4-
second output pulse to drive the IR command. Conveniently, if the video projector
power on function was part of a power up sequence programmed using Buffers, any
time the signal ‘vproj_power_on’ is driven high, the One Shot will ensure that a 4
second pulse is delivered to the IR driver.
Multiple One Shot
Many times you will find that when you need to use a One Shot to create a fixed-
pulse-length signal, you will need to do the same to other related signals. This can be
accomplished with many One Shot symbols, but because it is so commonplace there
is a special symbol available called the Multiple One Shot.
The Multiple One Shot symbol is essentially a bunch of independent One Shots
grouped into a single symbol. However, notice that each input/output pair represent
the ‘trigger’ and ‘out’ of a One Shot symbol; there is no ‘trigger*’ inputs or ‘out*’
outputs on the Multiple One Shot. In addition, all input/output pairs, though
independent of one another, share a common pulse length, specified by the double-
precision ‘time’ parameter.
Multiple One Shot Example: screen and drape relays
i1
i2
i3
i4
o1
o2
o3
o4
pulse_time 0.5s
Multiple One Shots
A1
A2
A3
A4
A5
A6
A7
A8
Relay Card
Drapes_Open
Screen_Up_rly
Screen_Down_rly
Drapes_Open_rly
Drapes_Close_rly
Screen_Up
Screen_Down
Drapes_Close
press87
press88
press89
press90
fb87
fb88
fb89
fb90
Touchpanel
When controlling motorized screens and drapes via low-voltage relays, care must be
taken to ensure that the relay closes long enough for the screen or drape
manufacturer’s interface to recognize it. In most cases such interfaces require only
about a half-second closure, but you cannot be sure that the user will press the button
for a full half-second. To account for this, a Multiple One Shot symbol can be used
as shown above.
Retriggerable One Shot
Another form of one shot is the Retriggerable One Shot, which is almost functionally
identical to the One Shot. The only difference is that the One Shot symbol will
ignore any changes on ‘trigger’ or ‘trigger*’ until ‘out’ goes low. The Retriggerable
One Shot will recognize a rising-edge on the ‘trigger’ input (or falling-edge on
‘trigger*) even while ‘out’ is high, causing it to ‘re-trigger’ and start the count all
over again. ‘Out’ will not go low until the full duration specified by the double
precision ‘time’ parameter has elapsed since the last trigger.
Primer – DOC. 6253 Crestron SIMPL Windows • 53