Difference between revisions of "Analog setpoint"
| [checked revision] | [checked revision] |
(→Differential signaling) |
|||
| Line 14: | Line 14: | ||
* Negative input | * Negative input | ||
* Ground | * Ground | ||
| − | The actual setpoint value will be calculated from the differential of positive and negative inputs. This eliminates error from ground currents and also reduces sensitivity to EMI noise. | + | The actual setpoint value will be calculated from the differential of positive and negative inputs. This eliminates error from ground currents and also reduces sensitivity to EMI noise. |
| + | {{tip|In typical servo drive, there are ANAIN+ and ANAIN- pins. Setpoint voltage is measured from the difference of voltage potentials between ANAIN+ and ANAIN-. Both ANAIN inputs must always lie within +/-12V from GND.}} | ||
[http://en.wikipedia.org/wiki/Differential_signaling Differential signaling on wikipedia] | [http://en.wikipedia.org/wiki/Differential_signaling Differential signaling on wikipedia] | ||
Revision as of 12:22, 15 May 2015
Analog setpoint is one of setpoint signal types used in motion control.
The most typical setpoint voltage range is +/-10V where
- -10V equals the most negative setpoint (-100%)
- 0V equals zero setpoint
- 10V equals most positive setpoint (+100%)
- Any value between is interpolated linearly
Another common voltage range is 0..5V where zero setpoint may be at 2.5 VDC (bias voltage).
Differential signaling
Analog setpoint input in target device is typically differential. Differential input requires 3 wires from source device:
- Positive input
- Negative input
- Ground
The actual setpoint value will be calculated from the differential of positive and negative inputs. This eliminates error from ground currents and also reduces sensitivity to EMI noise.
 | In typical servo drive, there are ANAIN+ and ANAIN- pins. Setpoint voltage is measured from the difference of voltage potentials between ANAIN+ and ANAIN-. Both ANAIN inputs must always lie within +/-12V from GND. |
Differential signaling on wikipedia
Example
Lets assume +/-10V is used as torque setpoint in VSD drive. In this case 0V equals no torque, and 10V equals 100% of peak torque configured in the drive, 5V equals 50% torque etc.
Peak torque can be configured to drive with GDtool as peak current limit. Torque and current are directly proportional, so torque setpoint is also a current setpoint.
