Siemens SIMATIC S5 Manual page 33

Machine Data and their Structure
When the machine data is input, an acceleration and deceleration ramp are generated.
The acceleration ramp is generated using the formula
f = F x (1 - e '"tb'T)) + f~~
Definition of the variables used:
: start-stop frequency
: maximum frequency
F : theoretical maximum frequency = (fmax- fSS)/O.95
: acceleration time [0...3 ~]
: constant for the ramp up time
The deceleration ramp is the mirror reflection of the acceleration ramp.
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Fig, 2/1 1 Acceleration and deceleration ramp of a job
To generate the ramps, three machine data are required:
Maximum frequency fmax:
Start-stop frequency fk
Rate of frequency increase a: quotient of the theoretical maximum frequency F and the ramp
The acceleration time tb is the time allowed to accelerate from a stationary position to frn~,
2 - 1 6
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this frequency is output at the maximum traversing speed.
this frequency is the maximum frequency at which the stepper
motor can start up from stationary (taking into account the load
and half and full step modes) and from which it can brake
immediately to become stationary,
up time constant ~
a = F/z [Hz/ins]
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