16
three of these counters can be individually reset under user control from the software
application.
The red failure LED on the front panel of the Controller Unit will illuminate if the
individual cycle fails. It will be extinguished if all the tests of that cycle pass. The LED
will be pulsing if the switch is randomly failing.
The 4 failure conditions of each half cycle may not all be active. The following table
shows the possible variations. The up and down strokes are independently set.
Test State
Failures -
Init
Max
Min
Bounce
No Testing
-
-
-
-
Contact Resistance
x
x
x
-
Bounce Testing
x
x
x
x
The
Maximum Contact Resistance, Minimum Contact Resistance and Maximum Bounce
Time are only valid if the test state is active.
Test Duration
The test duration is programmed by the user when the configuration data is created. The
half cycle time is specified in one millisecond resolution in a range from 0.025 to 5.000
seconds. The duration of the up or down stroke is dependent on the test state selected
for that half cycle. If
No Testing
is chosen, then the algorithms use the
Maximum Test
Time configuration value for that half of the cycle. The Minimum Test Time value can be
set to any valid time, it will have no affect. The maximum cycle rate is set by this
limitation. Assuming that the minimum time is used for both half cycles, 0.025 seconds,
the total test time is 0.050 seconds, or 20 cycles per second. Higher rates can be
ordered as an option by contacting TRICOR Systems.
When the contact resistance is measured, it is possible to measure switches faster since
there is information about the air cylinder plunger obtained by monitoring the contact of
the device under test. The maximum rate is still limited to 20 cycles per second.
However, some speedup is possible over the worst case settings that may be necessary
for configuring a switch to prevent random failures. This is where the
Minimum Test Time
value becomes useful. The speedup is diagrammed in figure 9.
