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Configuring an Application www.emersonct.com 47
Capture Sources and Destinations
Figure 77 shows a block diagram of the Capture object
Figure 77: Capture Object
Sources
CaptureTriggered - The CaptureTriggered signal is
read-only and indicates that the Capture component was
activated, and that data has been captured.
CaptureTriggered will activate on the leading edge of
CaptureActivate if the Capture component is enabled and
reset. Capture Triggered will remain active until
CaptureReset is activated.
Destinations
CaptureEnable - The CaptureEnable is used to enable or
"arm" the capture component. If the CaptureEnable is not
active, then the CaptureActivate has no effect, and the
CaptureTriggered remains inactive. Once the
CaptureEnable is activated, the Capture component is
ready and waiting for a CaptureActivate signal to capture
data. CaptureEnable is a read-only destination on the
Assignments view, and is accessible through a user
program.
CaptureActivate - If the Capture component is enable and
has been reset (CaptureTriggered is inactive), then the
rising edge of CaptureActivate will capture the four data
parameters and cause CaptureTriggered to be activated. If
the Capture component is not enabled, or has not been
reset, the CaptureActivate will be ignored.
CaptureReset - The CaptureReset is used to reset or
re-arm the capture component after it has been activated.
Once the capture has been activated, the
CaptureTriggered destination will be active. The capture
component cannot capture data again until it has been
reset. The capture component will automatically reset itself
if the CaptureEnable signal is removed.
Figure 78: Capture Timing Diagram
Figure 78 is a timing diagram that shows how the different
capture related sources and destinations function. The
three numbers located on the diagram are associated to
the following three notes respectively:
1. While CaptureTriggered is active, a rising edge on
CaptureActivate will be ignored. The capture
object can not activate again until it has been reset.
2. When CaptureEnable is deactivated,
CaptureTriggered automatically deactivates
because the capture object is automatically reset.
The captured data is retained until the capture
component is re-enabled and CaptureActivate is
activated.
3. CaptureActivate has no effect while the capture
component is not enabled.
Sources That Can Accurately Capture Data
Only a select few sources can accurately capture data. The
reason that only certain signals can accurately capture
data is because they are wired directly to the SM-EZ
Motion FPGA or the signal is generated internally by the
processor and can be activated in the FPGA. Signals that
are not wired to the FPGA or sent to the FPGA can be used
to capture data, but it will only be accurate to the Trajectory
Update Rate. This means that the capture will only occur
the next time the signal is updated and not when it actually
activates.
Sources that CAN accurately capture data:
• SM-EZ Motion Inputs
• Motor Encoder Marker Channel
• Index.#.CommandComplete
• Jog.#.CommandComplete
• Index.#.AtVelocity
• Jog.0.AtVelocity
• PLS.#.Status
All other Sources are only accurate to the Trajectory
Update Rate.
Assignments that Automatically Use Position Capture
The sources listed above automatically capture data each
CaptureEnable
CaptureActivate
CaptureReset
CaptureTriggere
d
Time
Command Position
Feedback Position
Master Position
Ca
p
tured Data
CaptureEnable
CaptureActivate
CaptureTriggered
Ca
p
tureReset
2
1
3