Thresholding

Operator Menu Location: Signal Comparators

Operator Bitmap:

Functional Description:
The Thresholding operator compares an analog input signal to high and low threshold levels. The operator's digital output is set HIGH if the input signal is greater than the upper limit; it is set LOW if the input signal is less than the lower limit; and it remains unchanged while the input signal is between the threshold levels. For the output to change from LOW to HIGH, the input must exceed the threshold level for a user-specified length of time-the rising dead-time. Likewise, for the output to switch from HIGH to LOW, the input signal must be less than the threshold level for a user-specified length of time-the falling dead-time. That is, the output y is defined by

where x is the input, is the high threshold level, is the low threshold level, R is the rising dead-time, F is the falling dead-time, and t is the loop sampling time.

User-Defined Properties:
Object Name. A string label that identifies the operator

Initial State. The output state (HIGH or LOW) at startup (at time t=0)
Low Threshold. The low threshold level,

High Threshold. The high threshold level,

Falling Dead-Time. The length of time a signal must satisfy the low threshold condition, for the output to switch from HIGH to LOW. The falling dead-time is denoted by F in the equation above, and is expressed in seconds.

Rising Dead-Time. The length of time a signal must satisfy the high threshold condition, for the output to switch from LOW to HIGH. The rising dead-time is denoted by R in the equation above, and is expressed in seconds.

Comments:
• Design Pad will issue an error on processing if the input pin is not connected
•The high threshold level must exceed the low threshold level,
•The falling dead-time must be greater than or equal to zero, F >=0
•The rising dead-time must be greater than or equal to zero, R >=0

See Also:
=, >=, >, <=, <, and != Comparators; High/Low Alarm