Program Control Outputs
The Program Control Output connector provides six pulse or gate
signals controlled by various actions of APWIN software. The pin
assignments are shown in the Table above. All lines are LSTTL
compatible.
The Reset output, pin 2, pulses high when the DCX-127 power is
turned on and whenever a Util Restore menu command is executed.
The Reset output would typically be used to normalize the condition of
external logic devices connected to a System One or System Two test
station at power up. It may also be invoked in a procedure by inserting
a Util Restore command into the procedure.
The Data Acquired output, pin 3, pulses high each time that a set
of data satisfies the settling algorithm. See the Sweep Settling section
for full details on the settling algorithm. This signal could be used, for
example, to cause a compact disc player to automatically advance to
the next track whenever a successful set of measurements is completed
on the preceding track. This is useful during an external frequency or
external amplitude test across a series of tracks of a test disc.
The Trigger output, pin 4, pulses high at the end of each delay
portion of the settling process. In a generator-based sweep, settling
delay is the time after the generator steps to a new value but before the
software starts examining data samples to see if they are settled. This
signal could be viewed on a dual-trace oscilloscope along with the
signal being measured, to verify that the delay has been optimally set
to discard “left over” data from the previous generator step. This is
useful when measuring systems such as 3-head tape recorders or
satellite paths, which have significant time delays.
The Trigger output of the DCX-127 could also be connected to the
trigger/gate input of the generator when the BUR-GEN module is
present. This will synchronize tone bursts in the sine trig mode with the
system’s readiness to make a measurement. The Trigger output could
also be used to strobe an external device being tested, such as an
analog-to-digital converter. This will help insure that the source is stable
before the conversion takes place.
The Sweep Gate output, pin 6, drops low at the beginning of a
sweep test and goes high at the completion of a test. In a nested sweep,
Digital Output
Description
Page 8
DCX-127 Multifunction Module User’s Guide
