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4 Programming of Motion Blocks 05.91

4.2.16 Axis synchronization with change of channel G200

If the same axis is traversed in AUTOMATIC or MDA mode at different times by two or more

part programs, the absolute position of the axis will no longer be identical with the respective

block end values. This may result in an unintended path offset in the course of program

execution. This problem is illustrated by the following example:

%1 Channel 1 %2 Channel 2 Absolute actual value

G90 G00 X100

. X = 100

. G90 G00 X250

X = 250

G90 X200

. X = 350

Block end value: X = 200 Block end value: X = 250

In this example, the path offset occurs as follows:

1. With %1 a traversing movement takes place in channel 1 to the position X = 100.

2. On start of %2 in channel 2 (synchronization with ”Program Start”) traversing takes place

from X = 100 to X = 250.

3. In channel 1 traversing is to take place to X = 200 ; at this position, however, there is still

the block end value X = 100 which leads to a traversing movement by 100.

4. This leads to the following result:

• Absolute actual value: X = 350

• Block end value in channel 1: X = 200

• Block end value in channel 2: X = 250

The channel-specific block end values do not coincide with the current actual value. The

values for channel 1 and channel 2 are not updated until ”Program Start” is repeated.

The function G200 ”Axis synchronization with change of channels” enables the actual values

of the axis to be updated and unintended path offset to be avoided. The following should be

noticed:

• No function other than G200 must be incorporated in the block.

• Synchronization is not carried out until all relevant axes have assumed the stop status, i.e.

the interface signal EXACT STOP FINE is active.

• Synchronization is carried out only for the channel in which G200 has been started.

• If G200 is programmed during a selected transformation of fictitious axes, the user has to

wait for the interface signal EXACT STOP FINE of all axes of one mode group.

• G200 takes no effect in the AUTOMATIC submodes TEACH IN, BLOCK SEARCH, SINGLE

BLOCK, OVERSTORE and DRY RUN FEEDRATE.

4–50

SINUMERIK 880, (PG)

Siemens SINUMERIK 880 GA2 Programming Guide

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