Danfoss MCO 305 Design Manual page 26

MCO 305 Design Guide
man_vel = man_vel + GET 1901
done = 1
ELSEIF (IN 4 == 1) AND (done == 0) THEN
man_vel = man_vel - GET 1901
done = 1
ELSE
done = 0
ENDIF
ENDWHILE
CSTOP
OUT 2 0
ENDIF
GOTO MAIN
/****************************** Sub programs start ********************************/
SUBMAINPROG
/******************************** Error handler ***********************************/
SUBPROG errhandle
err = 1
OUT 8 1
OUT 1 0
OUT 2 0
WHILE err DO
IF (IN 8) AND NOT (IN 1) AND NOT (IN 2) THEN
ERRCLR
err=0
ENDIF
ENDWHILE
OUT 8 0
sync_flag = 0
done = 0
RETURN
/*******************************************************************************/
ENDPROG
/******************************* End of program **********************************/
Position/Angle Synchronization (SYNCP)
Position synchronization (SYNCP) is closed loop position control with a moving target where the set-point
(commanded position) is the master position multiplied by the gear-ratio also considering any position off-
set. The slave position is controlled based on this set-point and the actual position feedback from the slave
encoder. Any position deviation will continuously be corrected considering maximum velocity, acceleration
and deceleration of the slave. The gear-ratio is set as a fraction (numerator and denominator) to avoid
rounding errors e.g. when using prime numbers. The gear-ratio must be 100% correct, even the smallest
rounding error will lead to position drifting over time.
When starting position synchronizing the actual slave position will be locked to the actual master position, it
is thus necessary to bring the slave into the right physical position with respect to the physical position of
the master. This can be done manually or be means of an automatic homing procedure (requires external
reference switches or absolute encoders).
The slave must be faster and more dynamic than the master in order to maintain accurate synchronization
both at maximum master velocity and during acceleration/deceleration. I.e. the slave must be able to
exceed the maximum velocity, acceleration and deceleration of the master to allow it to catch up if getting
behind the master. Already during the design phase it is thus important to consider making the least dyna-
mic shaft the master as this shaft will anyway be the limiting factor for the system performance.
26
__ Functions and Examples __
// Stop when leaving manual mode
// Reset "In manual mode" output when leaving manual mode
// Set error flag to remain in error handler until error is reset.
// Set error output
// Reset "In synchronizing mode" output in case of error
// Reset "In manual mode" output in case of error
// Remain in error handler until the reset is received
// Reset error when Input 8 is high and input 1+2 is low.
// Clear error
// Reset error flag
// Reset error output
// Reset sync_flag after an error
// Reset done flag after an error
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// Decrease manual velocity by 1 step when input 3 is set