Computer Drive Installation Instructions

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12 Functional Descriptions 09.01

12.18.11 GI monitors

Characteristic of the velocity setpoint with the characteristic rising above and falling below the warning threshold

approx.20%

approx.10% control reserve

MD 264*

Drive error threshold

MD 268*

max.setpoint (IPO STOP)

MD 1736*-1764*

Alarm limit velocity:

1st PaSa - 8thPaSa (param. set)

MD 1448*

Warning threshold

max

and a

max

7/8 · MD1448*

Hysteresis threshold

Reaction time

PLC interface signal:

Vel. warning thresh. reached

internal:

Velocity limitation approached

In NC channels where axes are traversed which are enabled for velocity/acceleration limitation,

the acceleration in the path is stopped as follows:

Path set velocity = path actual velocity

The acceleration of released spindles is stopped if:

Set speed = actual speed

Due to non-linear movements of the leading axes (circle, Spline, IKA, transformation, etc.), the

velocity of the following axis may increase despite an acceleration stop of the leading axes.

In order to reduce the path velocity, the actual path set velocity is evaluated with a reduction

factor (MD 335 "Minimum reduction factor with velocity limitation following axis warning

threshold"), similar to an override. The channel thus calculates the path set velocity as follows:

path_set

Vpath_set

· MD335

In doing so, the interpolation grouping of the axes involved in the path, as well as the active

links, remain unchanged.

If the following axis velocity falls again below the hysteresis threshold, the request for

velocity/acceleration limitation is reset for all axes and spindles of the mode group. The

reduction factor in the NC channels is reset to 100%.

In order to avoid oscillations within the range of the hysteresis threshold and to bridge

machining steps temporarily resulting in an unfavorable velocity/acceleration override, the

increase of the reduction factor can be slowed down by means of MD 336 "Velocity increase

factor".

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SINUMERIK 840C (IA)