Bypass Enable Chassis
The interlock system bypass enable chassis has been modified to contain two key switches. The right hand switch functions the same as on the original module. This is used to bypass individual elements on the splitter chassis.
The left hand switch is used to bypass all stop switches at the same
time. When this switch is activated, a strobe light on the bypass chassis
and another strobe light on the azimuth stow light box on the upper level
will begin flashing. In addition, all stop switches at the telescope will
begin flashing.
Stop Switch LED’s
The individual stop switch LED’s have been modified to provide additional status information.
The low level axis logic has been modified to eliminate the possibility
of inadvertently bypassing the telescope stop switches.
South Windbaffle Stop Switch
An additional stop switch was added to the south fork of the windbaffle
and added to the low level axis logic.
Azimuth Telescope Clamp
Modified the high level logic to allow the alignment clamp to be used
below 15 degrees. The clamp may still be used at zenith. The clamp
must be disengaged for the windscreen or telescope azimuth axes to receive
a CW or CCW motion permit. This is to prevent LVDT errors from moving the
windscreen with the clamp on and to prevent the telescope from attempting
to drive against the windscreen.
AZ and ALT Motor Ready signals
For the telescope to have AZ CW and CCW permits, both azimuth motor
1 and 2 drive amplifiers must be ready. Any internal interlock trips on
one amplifier will trip the other amplifier off. The same has been done
for the altitude axis.
Windscreen CW / CCW / UP / DN permits
The windscreen soft inhibits now follow the telecope soft inhibits. If the telescope receives an UP inhibit, then an UP inhibit is sent to the windbaffle as well. The same holds true for Down, CW, and CCW inhibits. By implementing the logic in this fashion, the windbaffle will no longer follow an out-of-balance telescope past the soft limits to an out-of-operating-range position.
Hatch Switch and Dog House Door Switch
These switches were moved from Splitter chassis Slot 2, channels 6 and
7, to Slot 8, channels 6 and 7.
Lightning Protection
The Allen Bradley communications network now has lightning suppressors
installed in the Interlock Rack, the windbaffle junction box, and in the
azimuth junction box. This will help suppress any induced transients in
the communications network between the PLC components. We will add a suppressor
in the altitude junction box in the future. We were not able to move the
telescope to a position that would allow for work in the altitude junction
box this trip.
Last updated 11/19/98.
boroski@fnal.gov