Beckhoff TS5066, Руководство пользователя

Страница: 12 / 31

PLC API
TS5066 12 Version: 1.0
Fig. 6: Figure 2: Actual velocity of an axis operated with corrected axis information.
Description
The beat effects result from information being missed or read twice. These occurrences can be detected and
countermeasures taken based on the cycle index, i.e. a counter that is incremented whenever network
variables are sent. The function block is designed such that
a) the axis structures received as network variables and the corresponding cycle index are required as input
for the block;
b) the axis information (set position and velocity) is corrected internally; and
c) an NC axis can be operated with the corrected information.
The cycle index and the cycle time(s) are transferred internally to the function block FB_TimeSync [
}
14] .
This block determines the frequency of the beat and a correction time for extrapolating the kinematic axis
information such that the beat effects are compensated. To this end the correction time is transferred to an
instance of the function block
FB_AxisExtrapolateValues [ } 17] , together with the received axis structure,
which calculates the corrected set positions and velocities. Note that by default the set acceleration is used
for correcting the position and the velocity. This feature must be deactivated in the event of non-smooth set
acceleration, e.g. for encoder axes
(stAxisSyncParameters.stAxisExtrapolateParameters.bUseAccForExtrapolation:=FALSE).The corrected set
values are made available in the form of an axis structure and can then be used for operating the axis.
Critical Operating Notes
Please ensure that the fcuntion block FB_AxisSync is called one time only in each plc cylce!
VAR_INPUT
VAR_INPUT
bEnable: BOOL;
iCycleIndex: WORD;