Capture Timing Diagram, Capture Object, Sources

Capture Sources and Destinations

Figure 77 shows a block diagram of the Capture object

CaptureEnable

CaptureActivate

CaptureEnable

CaptureActivate

CaptureReset

Time

Command Position

Feedback Position

Master Position

Captured Data

CaptureTriggered

CaptureReset

Figure 78: Capture Timing Diagram

Figure 78 is a timing diagram that shows how the different capture related sources and destinations function. The

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.

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

Configuring an Application

Emerson P/N 400361-00 Capture Timing Diagram, Capture Object, Capture Sources and Destinations

Models: P/N 400361-00