Short description

The output is set and reset depending on a configurable threshold and a differential value.

Connection	Description
Input Ax	Input Ax is one of the following analog signals: AI1 to AI8 (*) AM1to AM6 (if 0BA6) or AM1 to AM16 (if 0BA7) AN1...AN32 (if 0BA7) AQ1 and AQ2 SAQ1...SAQ16 (if 0BA7). The block number of a function with analog output
Parameter	A: Gain Range of values: ±10.00 B: Zero offset Range of values: ±10,000 On: On/Off threshold Range of values: ±20,000 Δ: Differential value for calculating the off parameter Range of values: ±20,000 p: Number of decimals Range of values: 0, 1, 2, 3
Output Q	Q is set or reset, depending on the threshold and difference values.
* AI1 to AI8: 0 to 10 V corresponds with 0 to 1000 (internal value).

A: Gain Range of values: 0.00 to 10.00

Parameter p (number of decimals)

Parameter p applies only to the display of On, Off and Ax values in a message text.

Parameter p does not apply to the comparison of On and Off values. (The compare function ignores the decimal point.)

Timing diagram A: Function with negative difference Delta

Timing diagram B: Function with positive difference Delta

Description of the function

The function fetches the analog signal at input Ax.

Ax is multiplied by the value of the A (gain) parameter, and the value at parameter B (offset) is added to product, i.e.

(Ax * gain) + offset = actual value of Ax.

Output Q is set or reset, depending on the set (On) threshold and difference value (Delta). The function automatically calculates the Off parameter: Off = On + Delta, whereby Delta may be positive or negative. See the calculation rule below.

Calculation rule

• When you set a negative differential value Delta, the On threshold >= Off threshold, and:
  Q = 1, if the actual value Ax > On
  Q = 0, if the actual value Ax <= Off.
  See the timing diagram A.

• When you set a positive differential value Delta, the On threshold < the Off threshold, and Q = 1, if:
  On <= the actual value Ax < Off.
  See the timing diagram B.

Particular characteristics to be noted when configuring

Refer to the help on analog block parameters in the Information on analog value processing section.

Special Functions Overview