Actual position is saved to non-volatile memory evry time brake switched on. When loosing logic power module try to save actual position so long enough energy is available.
After powering up modul compares saved positon with saved controll value. Are this values equal, the saved positon value is compared with the actual resolver position. If both positions equal no referencing is necessary.
 | When resolver is rotated exactly one turn, when power lost, the actual position is the wrong one. |
Encoder with index
After powering up modul compares saved positon with saved controll value. Are this values equal, the saved positon is set to actual position. The difference to the index is calculated. With the next moving command the calculated distance is compared with the real moved distance to the next index. If both values equal the module needs not to be referenced. After the first movement command the index must reached in a certain time. If an error occures while moving to index the reference is lost.
|
| When encoder is turned when power is lost it can happen, that module moves to next index with wrong position. (max. one motor turn) |
|
| When encoder is rotated exactly one turn, when power lost, the actual position is the wrong one. |