Noise Error Rate

Type:	Axis Parameter Register
RMC70 Address:	Primary Input: Fn:6, where n = 12 + the axis number Secondary Input: Fn:24, where n = 12 + the axis number
RMC150 Address:	Primary Input: Fn:6, where n = 24 + the axis number Secondary Input: Fn:24, where n = 24 + the axis number
System Tag:	Primary Input: _Axis[n].NoiseErrorRate Secondary Input: _Axis[n].SecNoiseErrorRate where n is the axis number
How to Find:	Axes Parameters Pane, All tab: Feedback
Data Type:	REAL
Units:	See Below
Range:	≥ 0
Default Value:	1000

Description

This parameter is designed to specify the noise detection on the feedback. It is primarily designed for MDT inputs, but also works well for analog voltage or current inputs. If a large change in the feedback is detected, the Noise Error bit will be set.

The Noise Error Rate defines the maximum allowable rate of change in the feedback of the axis. If the rate of change exceeds the Noise Error Rate for more than 3 loop times, then the Noise Error bit will be set. If the Noise Error bit becomes set, it may cause a Halt if so configured by the Auto Stops and if the Direct Output Status bit is off. During noise less than 3 loop times, the Actual Position (or the value measured by the axis' input) is estimated to allow recovery from electrical noise.

Make sure to set the Noise Error Rate to a value much higher than the maximum expected rate of change in the axis' units. For example, if the axis will be traveling at up to 200 pu/s, then set the Noise Error Rate to something much higher, such as 800.

Note:
The Noise Error bit may turn on because the Noise Error Rate parameter is set too low. The Noise Error Rate should be set to a value much higher than the expected velocity (or rate of change of pressure or force) of the axis. If your axis is experiencing Noise Errors, this is the first item you should check. Setting the Noise Error Auto Stop to Status Only to avoid halting due to an overly low Noise Error Rate parameter can cause significant control problems, because the Actual Position and Actual Velocity may still be incorrectly calculated.

Quadrature Inputs

The Noise Error Rate parameter does not apply to quadrature axes. Instead, if the RMC detects an illegal transition (both A and B signals transition simultaneously), or an overspeed condition (pulse frequency exceeds maximum specifications), a Noise Error will occur.

Units

The Noise Error Rate applies to all axes types. However, the Noise Error Rate units for each axis type may differ. The following table shows the Noise Error Rate units for each axis type:

Axis Type	Noise Error Rate Units
Position	pu/s
Velocity	pu/s2
Acceleration	pu/s3
Pressure/Force	Pr/s or Fr/s

Special Notes

The Noise Error Rate does factor out the current Actual Velocity, and therefore, it won’t trigger for simply going over speed. A high acceleration can trigger the Noise Error. However, the Noise Error Rate should always be set much higher than the expected velocity of the axis.