Marvin Test Solutions GX5280, User Manual

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Chapter 4 - Theory of Operation 27
Trigger Command
The trigger command causes the board to change its state to the Run state and can be originate from the following
sources:

PC (software)

External trigger control line

External event lines (16 lines)

PXI Trigger Bus Line.
PC (Software) Trigger
The software trigger originates within the PC. The PC bus trigger command takes effect immediately and overrides
other established trigger conditions.
External Trigger
External Trigger Control Line
External triggers originate from the external trigger line. Pulling this line low causes the board to change its state to
RUN. The external trigger line overrides other trigger conditions set for the GT-DIO board.
External Event Lines
It is also possible to set a conditional trigger command, which is activated upon receiving external event input lines.
This external event may be any expected value on all or part of the external event input lines. The 16 external event
lines are ANDed with pre-defined masks and compared with pre-defined events in registers D and T.
The external events trigger function is shown in Figure 4-8.
D
Mask
Reg.
D
Event
Reg.
T
Mask
Reg.
T
Event
Reg.
C
o
m
p
T
ri
g
g
e
r
C
o
n
tr
o
l
C
o
m
p
External
Event
Inputs
PC Bus
Trigger
Figure 4-8: External Events Trigger Block Diagram