Allen-Bradley Kinetix 5500, Справочное руководство

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Chapter 2
Behavior models used in CIP Motion
40
Rockwell Automation Publication MOTION-RM003I-EN-P - February 2018
selected event input sources. Event input sources currently supported by the object
are:
•
Registration 1
•
Registration 2
•
Marker
•
Home Switch.
These event input sources apply to each supported feedback channel.
See also
Event Capture Behavior on page 38
To facilitate accurate capture of both feedback position and time, hardware event
latches are typically implemented.
Two independent latches are defined for each registration input, one latch to
capture positive edge transition events and one to capture negative edge transition
events. This design enables capture of both registration events in applications with
narrow registration pulses where the rising and falling edges occur nearly
simultaneously.
In addition to the registration latches, a separate latch is also defined for the home
event capture. The home input event that triggers the Home Event Latch can be
any of a number of different combinations of home switch and marker input
events, for example, marker transitions, switch transitions, or switch transitions
followed by a marker transition.
With hardware-based event latches, event capture accuracy is, in general, only
limited by the latency of the associated event input. Registration and Marker event
inputs are lightly filtered so event capture accuracy is on the order of 1
microsecond (
µ
sec). In terms of position capture accuracy, that would be
calculated as the product of the event capture accuracy and the speed of the axis.
Home switch inputs are heavily filtered, in general, and therefore limited to an
event capture accuracy of 1 to 10 millisecond (msec). Thus, to get an accurate
position capture based on a home switch input transition, a homing sequence with
a slow homing speed is required.
See also
Event Capture Behavior on page 38
Because the registration time stamp is passed to the controller as part of the Event
Notification data, the controller can apply the event time stamp to the position
history of other axes in the system to interpolate their positions. This is
Event Latches
Event Time Stamps