ABB ACSM1 - Page 65

Drive control and features
65
t
1
: Rising edge of encoder DI2 signal (proximity switch signal) is detected when the
master position is 0°. The follower position is -130° (stored to signal 4.04 PROBE2
POS MEAS).
t
2
: Rising edge of encoder DI1 signal (proximity switch signal) is detected when the
follower position is 0°. The actual position of the encoder is -30° (stored to signal
4.03 PROBE1 POS MEAS). Distance between the follower position and the actual
position is 0° - (-30°) = 30°.
According to parameter 62.16 PROBE1 POS and 62.18 PROBE2 POS settings the
follower should be 120° behind the master.
The following phase shift between the master and follower is calculated and stored
as reference error 4.05 CYCLIC POS ERR.
(62.18 PROBE2 POS - 4.04 PROBE2 POS MEAS) - (62.16 PROBE1 POS - 4.03
PROBE1 POS MEAS) = [-120° - (-130°)] - [0° - (-30°)] = -20°
This error is added to 4.18 SYNC ERROR. The synchron error is corrected using
positioning parameters.
t
3
: Error has been corrected and the follower is 120° behind the master. Cyclic
function is ready for a new correction if necessary.
Note 1: Only after the active correction is finished is the next position latching
enabled.
Note 2: The cyclic corrections are always performed along the shortest path. This
must be taken into account in all rollover applications.
Note 3: In rollover applications, the correction range is limited to ±180°.
t
1
t
2
t
1
t
2
-130
-30
-20
0
x°
x° - 100°
-130°
30
360 = 0
x
° - 120°
100°
0°
-30°
t
3
t
3
340
-100°
x°
x° - 120°
DI1
DI2
DI2
DI1
DI2
DI1
0°
0°
-130°
4.03 PROBE1 POS MEAS
4.05 CYCLIC POS ERR
4.18 SYNC ERROR
1.12 POS ACT
Real actual position
CYC POS ACT ERR
4.04 PROBE2 POS MEAS
Encoder DI1
Encoder DI2
Master reference position
MASTER FOLLOWER