Analog Input Block

Purpose

The Analog Input (AI) block sends and receives analog data from an I/O driver or OPC server every time the Scan, Alarm, and Control (SAC) program scans the block.

Features

The Analog Input block:

  • Is a primary block.
  • Can be used as a stand-alone block.
  • Generates alarms when values are outside of defined limits.
  • Sends and receives values from an I/O driver or OPC server when placed in Automatic mode.
  • Receives values from operator input in the iFIX WorkSpace, from scripts, from Program blocks, or from Easy Database Access programs when operating in Manual mode.
  • Can be used in a chain with exception-based or time-based processing.
  • Can use linear scaling on values received. The following formula is used to determine the linear scale value:

The equation for a line is Y = mX + b

Where Y is the scaled output value, X is the raw value from the PLC, m is the slope of the line and b is the y intercept.

The slope for our linearization is defined by output range divided by the input.

m  =  (ScaleHigh - ScaleLow ) / (RawHigh - RawLow)

The y intercept is determined by using the low values and the slope.

b = ScaleLow - m(RawLow)

In the analog block this results in the block's current value is equal to the driver value times the slope plus the y intercept.

X_CV = (IO value)m + b  

The driver value equates to the block current value minus the y intercept divided by the slope.

IO Value = (X_CV – b) / m

 

Typical Uses

Example

Fields

Important Notice

You do not have the latest version of iFIX! You are missing out on the newest capabilities and enhanced security.

For information on all the latest features, see the iFIX product page.

For more information on upgrades, contact your GE Digital sales agent or e-mail GEDClientServices@gevernova.com.

For the most up-to-date documentation, go here.