Difference between revisions of "Analog setpoint"
From Granite Devices Knowledge Wiki
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[[File:Noise1.gif|thumb|Analog reference signal is ideally clean and precise (blue). However, in problematic cases [[Electromagnetic interference|electromagnetic interference]] is coupled to the signal (red) causing inaccuracies like noise and offset error/drifting.]] | [[File:Noise1.gif|thumb|Analog reference signal is ideally clean and precise (blue). However, in problematic cases [[Electromagnetic interference|electromagnetic interference]] is coupled to the signal (red) causing inaccuracies like noise and offset error/drifting.]] | ||
| − | Analog | + | Analog setpoint is one of [[setpoint signal]] types used in motion control. |
| − | The most typical | + | The most typical setpoint voltage range is +/-10V where |
| − | * -10V equals the most negative | + | * -10V equals the most negative setpoint (-100%) |
| − | * 0V equals zero | + | * 0V equals zero setpoint |
| − | * 10V equals most positive | + | * 10V equals most positive setpoint (+100%) |
* Any value between is interpolated linearly | * Any value between is interpolated linearly | ||
| − | Another common voltage range is 0..5V where zero | + | Another common voltage range is 0..5V where zero setpoint may be at 2.5 VDC (bias voltage). |
==Differential signaling== | ==Differential signaling== | ||
| − | Analog | + | Analog setpoint input in target device is typically differential. Differential input requires 3 wires from source device: |
* Positive input | * Positive input | ||
* Negative input | * Negative input | ||
* Ground | * Ground | ||
| − | The actual | + | 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. |
[http://en.wikipedia.org/wiki/Differential_signaling Differential signaling on wikipedia] | [http://en.wikipedia.org/wiki/Differential_signaling Differential signaling on wikipedia] | ||
==Example== | ==Example== | ||
| − | Lets assume +/-10V is used as torque | + | 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 | + | 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. |
[[Category:Signals]] | [[Category:Signals]] | ||
[[Category:Glossary]] | [[Category:Glossary]] | ||
Revision as of 21:18, 24 June 2013
Analog reference signal is ideally clean and precise (blue). However, in problematic cases electromagnetic interference is coupled to the signal (red) causing inaccuracies like noise and offset error/drifting.
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.
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.
