Instruction of absolute value system
Absolute encoder can simultaneously record the position of servo motor and turns of servo motor rotation. Single-turn resolution is 1048576, and turns of 16-bit Max. 65535 can be recorded. Absolute encoder will back up position data when the upper servo drive is powered off. After power-on reset, machine absolute position can be calculated without re-starting the original zero point(When using incremental encoders in servo drives, the position feedback is 0 after power on. By resetting the origin to find the point where the mechanical position feedback is truly 0, the servo motor can operate correctly on the mechanical equipment; After using the absolute value encoder and powering it on again, the correct position feedback value will be calculated based on the information backed up by the encoder.)
Note:
- SV3 servo drives support absolute position linear mode and absolute position rotation mode, which is suitable for position, speed, and torque mode;
- E.917 encoder battery Error occurs when battery is switched on for the first time. It shall set P20.05=1 to reset the encoder Error, and then perform the home.
- To modify the direction reservsing selection of P04.01, it shall reset the home;
- In absolute position mode, the servo automatically detects whether motor number is absolute encoder motor, if the setting is wrong, Error E.019 occurs(encoder matching Error).
Object related to absolute value system
Function selection object:
P04.02 - Selection of Position Feedback System
| P04.02 - Selection of Position feedback System | |||||||||
| Index - Subindex | 0x2004-03 | ||||||||
| Data type | UINT16 | ||||||||
| Accessibility | Readable/writable | ||||||||
| Unit | - | ||||||||
| Default | 0 | ||||||||
| Min. | 0 | ||||||||
| Max. | 2 | ||||||||
| Setting and effective mode | Stop setting/power-on reset | ||||||||
| Related mode | ALL | ||||||||
| Note | Set absolute value system
|
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P20.05- Encoder reset
| P20.05- Encoder reset | |||||||||
| Index - Subindex | 0x2020-06 | ||||||||
| Data type | UINT16 | ||||||||
| Accessibility | Readable/writable | ||||||||
| Unit | - | ||||||||
| Default | 0 | ||||||||
| Min. | 0 | ||||||||
| Max. | 2 | ||||||||
| Setting and effective mode | Stop setting/power-on reset | ||||||||
| Related mode | - | ||||||||
| Note | Encoder reset
|
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Encoder feedback parameter objects
| Parameter index | Parameter | Name | Unit | Range | Data type | Accessibility | PDO |
| 0x2009-2B | P09.42 | Number of encoder turns | Turn | 0~65535 | UINT16 | RO | - |
| 0x2009-2C | P09.43 | Encoder single turn position | Encoder unit | 0~(231-1) | INT32 | RO | - |
| 0x2009-2E | P09.45 | Encoder absolute position Low 32 bits | Encoder unit | (-231)~(231-1) | INT32 | RO | - |
| 0x2009-30 | P09.47 | Encoder absolute position High 32 bits | Encoder unit | (-231)~(231-1) | INT32 | RO | - |
Note:
- P09.43 is the encoder single-turn position, and its range is 0 to encoder resolution. In case of 23-bit encoder, the range is 0~(223-1);
- P09.42/P09.43 are both encoder feedback data;
- As P09.42 is an unsigned number, absolute position of absolute encoder is calculated as follows:
- Encoder absolute position = P09.42 × encoder resolution + P09.43(P09.42<32768)OrEncoder absolute position = (P09.42-65536) × encoder resolution + P09.43 (P09.42≥ 32768)
- P09.45 and P09.47 are used to display the absolute position of encoder. The formula is as follows: absolute encoder absolute position = P09.47×232+ P09.45.
Precautions for absolute value system
- If the battery is connected for the first time, E.917 (encoder battery Error) will occur. It requires to set P20.05=1 to reset the encoder Error, and then perform absolute position system operation;
- If the detected battery voltage is less than 3.1V, E.921 (encoder battery Alarm) will occur. Please replace the battery; Ensure that the servo drive is powered on but not running when replacing the battery;
- If the servo drive is powered off, the battery is detached or replaced, please use P20.05=1 to reset the encoder Error after powered-on, and then perform the homing operation;
- If the servo drive is powered off, Max. speed of the motor should not exceed 6000rpm, otherwise, encoder position data may be recorded improperly;
- Please ensure that battery SOC and storage conditions do not damage the battery.