Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 62
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TTL Input 1 and TTL Input 2
In this section, you will find the parameters related to TTL Input 1 and TTL Input 2.
Polarity
The TTL Inputs are implemented through optical isolators. This is done so that current
can be passed through them from far away in a factory, without concern for ground
loops or voltage differences that might exist over long distances. With this being the
case, it is impossible to discuss the inputs in terms of “high” or “low”. What matters is
whether current is flowing into the optical isolator or not. When current is flowing, we
consider the input to be “active”. When current is not flowing, we consider the input to
be “inactive”. (For most application, “Active” will correspond with TTL High, but this
depends on how the input is actually connected at the source (controlling) device.)
The
Polarity
control allows you to specify whether the “Action” (described below) is
initiated as a result of the TTL Input being “Active” or “Inactive”.
Action
The
Action
specifies what the Mach-DSP will do when the TTL Input is in the condition
described by
Polarity
. Possible actions are:
Ignored (the TTL Input has no affect on the Mach-DSP)
Deactivate X-axis servo
Deactivate Y-axis servo
Deactivate both X-axis and Y-axis servo
Mute X-axis Command Input
Mute Y-axis Command Input
Mute both X-axis and Y-axis Command Input
Select Tuning 1 or 2
Select Tuning 3 or 4
Select Tuning 1-2-3-4
Request exercise of X-axis scanner
Request exercise Y-axis scanner
Request exercise both X-axis and Y-axis scanner
(Note that the “exercise” actions will only have an effect if exercising has been setup in
the scanner tuning, using the parameters on the Pangolin-only tab. Exercising is also
only possible if the scanner does not have any external mirror bumpers in place,
because exercising involves continuous rotation of the scanner.)
