Analog differential trigger

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 (*)

  • AM1 to AM6 (if 0BA6), AM1 to AM16 (if 0BA7), or AM1 to AM64 (if 0BA8)

  • NAI1 to NAI32 (if 0BA7 or 0BA8)

  • AQ1 and AQ2 (if 0BA7), or AQ1 to AQ8 (if 0BA8)

  • NAQ1 to NAQ16 (if 0BA7 or 0BA8)

  • The block number of a function with analog output

Parameter

Gain

Range of values: -10.00 to 10.00

Offset
Range of values: -10000 to 10000

On: On/Off threshold
Range of values: -20000 to 20000

Δ: Differential value for calculating the off parameter
Range of values: -20000 to 20000

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.

Overview