Quadrature Decoder Tool
| Tool Name | Short Name | Inputs Count/Type | Outputs Count/Type/Name |
|---|---|---|---|
| Quadrature Decoder Tool | QDC | 2 paired I/O input lines |
1 event stream: QDC<i> |
Diagram
QDC tool functional and wiring diagram
The quadrature edge detector is fed by a pair of signals named A and B delivered by a phase-quadrature motion encoder device.
The source selectors allows selected pairs of adjacent input-capable GPIO input lines to be selected as A/B input sources.
See also: QuadratureDecoderToolSources
The tool includes the following function blocks:
| ● | A quadrature edge detector |
| ● | A backward motion compensator |
| ● | A position counter |
The tool delivers:
| ● | One I/O Toolbox event stream named QDC<i>. |
| ● | A direction status bit indicating the direction of the motion. |
| ● | A position status word indicating the position offset. |
Operation
The Quadrature Decoder Tool decodes the A/B signals and delivers 1, 2, or 4 events every A/B cycle, possibly filtered by the backward motion compensator.
Quadrature edge detector
The quadrature edge detector analyzes the transitions on the A/B lines. It delivers:
| ● | An event stream, named U, having 1, 2, or 4 events every A/B cycle according the QuadratureDecoderToolActivation settings |
| ● | An identification of the phase between A and B (A leads B or vice-versa) |
Quadrature edge detector waveforms
The U stream may be filtered by the backward motion compensator before being delivered to the QDC<i> output.
The phase indication may be inverted according to the QuadratureDecoderToolForwardDirection settings before being delivered to the Direction output.
Backward motion compensator
The backward motion compensator (BMC) filters the U stream according to the QuadratureDecoderToolOutputMode setting.
When set to Unfiltered, all the events of the U stream are delivered to the QDC<i> output:
BMC waveforms - Unfiltered
When set to ForwardOnly, only the events corresponding to the forward direction are delivered to the QDC<i> output:
BMC waveforms - Forward Only
When set to FirstPassForwardOnly, only the events corresponding to the first pass in the forward direction are delivered to the QDC<i> output:
BMC waveforms - First Pass Forward Only
Position Counter
The position counter increments by 1 for any U event corresponding to the forward direction and decrements by 1 for the backward direction.
The counter can be reset using the QuadratureDecoderToolPositionReset command.