3156B User Manual
Racal Instrument © 2005
Getting Started 1-23
Data lines for the digital outputs are routed from the DAC inputs
through special buffers, directly to the output connectors and
therefore, these outputs are always active, regardless if the digital
patterns mode is selected or not. All run modes that are available for
the standard and arbitrary waveforms are also available for the digital
patterns outputs.
Video Stroke
Waveforms
Video stroke waveforms are used for analog monitors where one
channel drives the “X” axis and the other channel drives the “Y” axis.
There are ten standard video stroke characters built in the 3156B
software however, using the arbitrary capability of the instrument, one
can build and generate multiple characters to match any application.
The standard, built-in characters are: Cross Locator, Cross Hair,
Positioned Square, Vertical Marker Line, Horizontal Marker Line, Right
Hand Arrow, Left Hand Arrow, Diamond Overlay, Inverted Triangle
and Upright Triangle.
The video stroke generator can easily be adopted for testing XY
recorders. Using the automatically stepped offset generator, the offset
motion covers a span of -4.995V to +4.995V with step increments as
small as
±
1mV (up to
±
9.99V).
Output State
The main outputs can be turned on or off. The internal circuit is
disconnected from the output connector by a mechanical switch
(relay). This feature is useful for connecting the main outputs to an
analog bus. For safety reasons, when power is first applied to the
chassis, the main output is always off.
Enable State
In general, the 3156B starts generating output functions only after an
enable command has been received. The source of the enable
command is selectable from software command, front panel trigger
input or from a backplane TTLTrg(n) line. The output waveform, in
some cases, can be stropped using the enable off command.
Summary of run modes and their respective enable sources is given in
Chapter 3 of this manual.
