Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 64
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Amount
The
Amount
is a qualifier that is used with some of the
Conditions
above. The value that
the
Amount
corresponds to depends on the selected condition. For example, if the
Condition
is set to “If Servo board temperature is greater than Amount”, then the
Amount
is used to specify the temperature in degrees. For Position Error and Velocity
related conditions, you can use the built-in Oscilloscope feature to determine
appropriate values to enter into
Amount
.
Dwell time
(seconds)
The
Dwell time
specifies the amount of time that the TTL Output will be maintained in
the state specified by
Polarity
, even after the
Condition
no longer exists. For example, if
Condition and Amount are set to “If X-axis coil temperature is greater than 60 degrees”,
then the TTL Output will become asserted immediately upon that condition. But lets say
that the coil temperature is 60 degrees for only a split second, and then it goes back
down to 59 degrees. For safety reasons, you might want the Mach-DSP to continue to
assert this condition for some number of seconds.
Dwell time
takes on a more important and more meaningful role in applications that
evaluate whether or not scanning is taking place (i.e. as a “scan-fail safeguard”). In
these applications, it is often the case where scanning occurs, then pauses, then
resumes scanning, and then pauses (for example, pausing on the corners of letters or
graphic shapes). These pauses typically occur for less than one millisecond. For
evaluating whether or not scanning is happening, the
Condition
could be set to “If either
X-axis or Y-axis Velocity is greater than 6”, and
Dwell time
can be set to 0.001 or 0.002.
The
Dwell time
allows you to specify zero (for immediate assertion and de-assertion of
the TTL output), or 0.001 (for 1 millisecond of dwell time) or values up to 15 seconds.
TTL Indicators on the Mach-DSP board
The Mach-DSP board has two red LEDs, which correspond to the two TTL Outputs, and
are each illuminated when the corresponding TTL Output is “Active”. See section 5.0 for
more information.
