Question:
Why does the positioning drive still move with low speed, although the value 0 % is applied to the V-override-input?
Answer:
According to the definition the traversing profile generators (linear and S-ramps) of the 9300 EP positioning controller permit only traversing speed ≠ 0. With traversing speed = 0 no positioning could be effected. The position target would never be reached and the program would 'hang up'.
In detail:
The traversing profiles (linear, S-ramps) can process speed values in a certain internal resolution. Compared to the S-shape generator the linear profile generator's resolution is higher by factor 16384. As the minimum possible speed derives from the internal resolution, the minimum adjustable speed of the linear profile generator is lower by factor 16384 compared to the S-shape generator. Therefore, a drift of the linear profile generator can generally only be detected over a longer period of time.
In the Lenze default setting range (C1204 = 1, C1202 = 1, C1203 = 1, C1240 = 50) the minimum possible traversing speed is:
- Linear: 1/16384 inc/ms = 0.000000931 r/s = 0.000056 rpm
- S-ramps: 1 inc/ms = 0.015 r/s = 0.92 rpm
The used formulas can be fount in the manual of the 9300 EP positioning controller, part D2.1 under chapter '7.6 positioning control POS'.
Suggested solution for the stop with V-override = 0 %:
For stopping the drive during the operating positioning program function block 'Program-Stop' is available. Following application can stop the drive with V-override = 0 %:
- Detect V-override = 0 % by CMPx comparator and
- approach 'POS-PRG-STOP' directly
