Danfoss MCO 305 Design Manual page 142

MCO 305 Design Guide
PID
Summary
Syntax
Parameter
Return Value
Description
Command Group
Syntax Example
POSA
Summary
Syntax
Parameter
Description
Command Group
Cross Index
Syntax Example
Program Sample
142
__ Software Reference __
Calculates PID filter.
u(n) = PID e(n)
e(n) = actual deviation (error) for which the PID filter should be used
u(n) = result of the PID calculation
A PID filter can be calculated with this function. The PID filter works according to
the following formula:
u(n) = ( KP * e(n) + KD *(e(n)-e(n–1)) + KI* e(n) ) / timer
where the following is true:
e(n) error occurring at time n
KP proportional factor of the PID
control
KD Derivative Value
KI Integral Factor (limited by
Integration Limit)
timer controller sample time
The corresponding factors can be set with the following commands:
SET PID KPROP 1
SET PID KDER 1
SET PID KINT 0
SET PID KILIM 0
SET PID TIMER 1
The following syntax example also show the default allocation of the factors.
I/O
e = INAD 53
u = PID e
PRINT "input = ",e, "output = ",u
Positioning in relation to actual zero point.
POSA p
p = Position in user units (UU) absolute to the actual zero point; the UU
corresponds in the standard setting the number of quadcounts.
The axis can be moved to a position absolute to the actual zero position.
When the POSA command exceeds the Negative or Positive Software End Limit (para-
meters 33-41 or 33-42) the program continue with the next command after an error.
NB!:
If a temporary zero point, set via SET ORIGIN, exists and is active, then the
position result refers to this zero point.
NB!:
If an acceleration and/or velocity have not been defined at the time of the POSA
command, then the procedure will take place with the values of parameters 32-84
Default Velocity and 32-85 Default Acceleration.
ABS
VEL, ACC, POSR, HOME, DEF ORIGIN, SET ORIGIN,
Parameters: 32-12 User Unit Numerator, 32-11 User Unit Denominator
POSA 50000 /* move axis to position 50000 */
POS_01.M
®
MG.33.L4.02 – VLT is a registered Danfoss trademark
e(n)
/* set KP 1 */
/* set KD 1 */
/* set KI 0 */
/* Integration limit 0 */
/* Sample time = 1 */
KPROP
+
u(n)
+
+
KINT
KILIM
KDER