Specifications

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3BUS 208 000 R1301 165Control Panel Operation
Self Test
The Self Test push button serves as a lamp test for the LEDs on the panel, as well
as being able to initiate a check on the positioning subsystem operation when the
scanner is in the LOCAL mode. In all scanner modes except LOCAL, when the
Self Test push button is pushed, the various LEDs on the panel will sequentially
light up momentarily to indicate their condition. This test has no impact on what
other functions the scanner is performing at the time.
When the scanner is in LOCAL, the function of the Self Test push button changes
to include a check on the positioning subsystem. Under the LOCAL condition, the
initial push of the button will start the usual LED lighting cycle, but when released,
the OFF SHEET LED will extinguish and the scanner will attempt to resynchonize
the encoder. The following sequence will take place.
• unsynchronizes the encoder
• moves the head package to the home limit switch
• resynchronizes the encoder
• moves the head package to the off-sheet position
Note: The test can be started with the head located anywhere along the
frame. When the test starts the head will move toward the home
limit switch at a high slew rate. If there is a need to stop the head
at any time during this transition, simply press the LOCAL push
button once more, stopping the head. This will terminate the self-
test request.
The actual check being performed in this test, is to verify that the encoder count at
the point of the head coming off the limit switch, matches the count when the
encoder was initially synchronized. Any error in this will result in the push button
LED flashing. In this case, run the test again to clear the alarm and check the
Encoder Diagnostic screen in the ft utility to see the details of the encoder’s history.
It is possible that the test failure may only be the result of the system having lost
some counts during an earlier scan. In that case, the Encoder Diagnostic screen
should be visited periodically to make sure that the condition is not a chronic one.
Some things which can cause failure are:
• Scanning too fast (can lose encoder counts)
• Defective encoder
• Defective encoder mounting (slipping)
• Defective cabling from encoder to the ECF board
• Defective ECF board