Allen-Bradley LOGIX 5000 Reference Manual page 293

Drives
Ramp Profile
To produce a Ramp profile, set JerkRate such that (JerkRate * DeltaT)
AccelRate and/or DecelRate.
In Ramp Profile mode, the SCRV instruction always produces a rate of change
equal to the programmed AccelRate or DecelRate until the difference between
Out and In requires less then AccelRate or DecelRate to reach endpoint.
HoldMode = 0 operates the same as HoldMode = 1. When HoldEnable is set,
Out is immediately held and Rate becomes zero.
The following diagram illustrates how the instruction modifies Out.
(1) When Initialize is set, the instruction sets the following:
Outn = InitialValue
Outn-1 = Outn
Raten = 0
Raten-1 = 0
(2) When HoldMode is cleared, Out is moving toward In, and HoldEnable is set,
the rate begins decreasing towards zero at the jerk rate. Due to the JerkRate, Out is
held at whatever value it had when the rate reached zero. When the Out is finally
held constant, it has a value that is different from the value it had the instant that
HoldEnable was set.
When HoldMode is set, Out is moving toward In, and HoldEnable is set, the rate
is immediately set to zero. Out is held at whatever value it had when HoldEnable
was set.
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Chapter 2
293