Analog threshold trigger

Short description

The output is set or reset depending on two configurable thresholds (hysteresis).

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 threshold
Range of values: -20000 to 20000

Off: Off threshold
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 set thresholds.

* AI1 to AI8: 0 to 10 V corresponds with 0 to 1000 (internal value).

Parameters On and Off

The On and Off parameters can be provided by the actual value of another already-programmed function:

For the 0BA7 and later version devices, you can additionally use the actual values of the following already-programmed functions:

You select the required function by the block number.

0BA4:

A: Gain
Range of values 0.00 to 10.00

 

0BA2, 0BA3:

These parameters apply:
G: Gain in [%]
Range of values 0% to 1000%
O: Offset
Range of values -999 to 999
On: On threshold
Range of values 0 to 9999
Off: Off threshold
Range of values 0 to 9999

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

Description of the function

The function reads the value of the signal at the analog input Ax.

This value is multiplied by the value of parameter A (gain). Parameter B (offset) is added to the product, hence

(Ax * Gain) + Offset = Actual value Ax.

Output Q is set or reset depending on the set threshold values. See the following calculation rule.

0BA2, 0BA3:
The function is as follows:
The offset parameter is added to the read analog value. The sum is multiplied by the value of the gain parameter.
Value = (AI+offset)*gain
Output Q is set to 1 if the calculated value exceeds the on threshold (TH high).
Q is reset to 0 when the value reaches or drops below the off threshold (TH low).

Calculation rule

  • If threshold (On) ≥ threshold (Off), then:
    Q = 1, if the actual value Ax > On
    Q = 0, if the actual value Ax ≤ Off.

  • If threshold (On) < threshold (Off), then Q = 1, if
    On ≤ the actual value Ax < Off.

Particular characteristics to be noted when configuring

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

Note

The decimal point setting must be identical in the minimum and maximum range.