Loop Time Adjust

Type:

Controller Register

Address:

RMC75: n/a

RMC150: n/a

RMC200: %MD18.21

System Tag:

_Controller.LoopTimeAdjust

How to Find:

Address Selection Tool → Controller

Data Type:

REAL

Range:

-8,000,000 to 8,000,000 nsec/sec

Default Value:

0

Accessibility:

Read/Write

Description

The Loop Time Adjust register specifies the number of nanoseconds per second to adjust the motion loop by. This register is intended to be used to adjust the motion loop to align with and stay synchronized to an external source. For more details, see Loop Time Synchronization.

The actual duration of each motion loop time period will adjust in increments of 8ns, but the RMC will dither the duration to give a total effective adjustment at a 1ns resolution over a period of 8 seconds.

The accepted range is -8,000,000 to +8,000,000. Typically, the values required to synchronize to an external signal will be on the order of ±50,000 ns/s, which at a 1ms loop time will be ±50 ns/loop. Using larger values closer to the range max and min is intended only to make large corrections in the alignment of the motion loop and may cause problems with certain inputs such as SSI and analog. Therefore, large values should only be used upon initial synchronization, with the machine in a state where disruptions to SSI or analog feedback will not cause problems.

This value is a REAL but is rounded to an integer internally. For example, 50.4 is equivalent to 50.

This register is not saved to flash and will always default to zero (0) on startup. Support for non-zero values requires minimum CPU and Base module firmware versions as follows:

 

See Also

Loop Time Synchronization

Send comments on this topic.

Copyright © 2024 Delta Computer Systems, Inc. dba Delta Motion