Honeywell Experion MX Operator's Manual page 51

switch output is connected to a digital input on an alley EDAQ PCB, and is reported to the
rest of the control system for interlocking purposes.
Purpose:
If the upper head does not completely cover the lower head, radiation from sources is not
properly captured and poses a hazard.
As a result, when heads are split apart, all sensors lose interlock permissions, source
shutters are closed, and lasers are turned off. No shutter can be opened while heads are
split due to a lack of interlock permission.
Scanner drive motion functions are disabled when the heads are split.
2.3.3.5 Sensor-in-place interlock
Description:
A switch on radiation sensors to ensure that they are mounted to the head platform. The
switch is connected to a digital input on the sensor EDAQ boards.
Purpose:
This switch ensures that there is an appropriate capture device facing a source to limit
radiation leakage. A sensor shutter will not open if the sensor-in-place interlock is not
satisfied.
2.3.3.6 Shutter closed signal level
Description:
A software algorithm that monitors signal levels from receivers opposite from radiation
sources.
Purpose:
The algorithm looks for signal levels below a threshold level to ensure that shutters are
closing properly.
2.3.3.7 Failsafe shutter power interlock
Description:
An interlock board on all radiation source assemblies that controls access to shutter
power.
Purpose:
The interlock board uses a monitoring output from the sensor EDAQ to ensure that the
EDAQ hardware and software are operating properly prior to enabling power to shutter
mechanisms. This failsafe prevents unintended opening or failure to close source shutters
due to latched digital outputs, software program freezes, or incorrect sensor type software
connected to radiation sources.
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SCANNER SAFETY AND LOCAL CONTROLS
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