Last update: 2021/04/27 20:10
safety:pass
https://wiki.pangolin.com/doku.php?id=safety:pass
https://wiki.pangolin.com/
Printed on 2022/07/28 09:15
in PASS as a measure of redundancy. If there is an effect that is scanning very quickly, and which would
satisfy the “Minimum Velocity”, but if this is a very small effect, PASS will blank the color and intensity
signals until the Effect Size resumes a safe level. The Effect Size is not adjustable on this version of PASS.
Note that during momentary interruptions of color and blanking signals, PASS does not affect the Shutter
output.
Control Panel Signals
A control panel may optionally be used with PASS. The control panel may have a ESTOP switch (i.e.
mushroom emergency stop switch), as well as a manual reset button, which may be embodied as a
keyswitch or push button. When a control panel is used with PASS, a Manual Reset is required in order to
activate PASS, and thus, start projector operation. In most cases, this is a simple keyswitch action but
could also be a simple momentary push button. And when a Control Panel is used, PASS continually
monitors the ESTOP button. If the ESTOP is pressed, PASS will immediately terminate all color and
intensity signals, and forcibly close the shutter. PASS will also open the projector interlock signal path
(ILDA pins 4 and 17).
Beam Power Monitor
The Beam Power Monitor is perhaps the most unique and important aspect of PASS. The Beam Power
Monitor is able to make sure that the light coming out of the projector conforms to what is expected.
When PASS commands that no light should be emitted from the projector, PASS will verify that this is so,
by observing the Beam Power Monitor. If light is coming out of the projector when it is not supposed to
be, PASS will forcibly blank the color and intensity signals, close the shutter, and open the projector
interlock signal path. PASS does this because this would be considered a critical problem. Likewise, if
PASS detects that light is commanded from the computer, but is not coming out of the projector, PASS
will take this same kind of critical action, because this could be a sign that the light sensor is not working.
And finally, PASS will measure the Beam Power against a “Maximum Safe Beam Power” adjustment, and
if it is exceeded, PASS will take the same critical action, forcibly blanking the color and intensity signals,
closing the shutter, and opening the projector interlock. Any of these conditions requires the power to be
recycled, or a Manual Reset. Under normal circumstances, this will never occur. There should always be
congruence between commanded power and actual light coming from the projector. And light coming out
of the projector above the “Maximum Safe Beam Power” level is, of course, also a sign of trouble. See the
section on “Using PASS with a light sensor” below for additional information.