This category is used to scale the input of an analogue tag value to a real value.

Range

      The Range is the range of the input, select one of the common ranges or select No Input Scaling if the value does not need to be scaled. To calculate a custom range that is not in the list of ranges, click the "Calculate Custom Scale" button. To read a floating point number out of a PLC's integer data file, the value must be multiplied by 10 in the PLC and set the Input Range to Custom Scale and set the scale value to 0.1000.

      When an Input Range is selected, the Scale and Offset edit controls are automatically updated with the correct values to produce this range.

NOTE:

For reading of parameters ie SV, PV etc from Shimaden controllers, set the Range to No Input Scaling.

Resolution

This field is the number of steps in the data value, 1023 means 10 bit, and 4095 means 12 bit.

Software Offset

The software offset is turned on when a 4-20 mA signal is connected to an input which reads 0-20 mA.

Scale

This value is the scale factor used to convert the input range to the required real value.

Offset

This value is a constant used to calculate the real value from the raw input.

If the Input Range is set to Custom Scale, the following formula is used

     Line Reading = raw input * scale + offset + calibration      

Calculate Custom Scale

This dialog box can be used to set the scale of the tag to one that is not provided in the list of input ranges. To calculate a scale, press the Calculate Custom Scale button. Remember when entering a scale, it must match the scale of the attached transducer for the input to be calculated correctly.

See Calculate Custom Scale.

Calibration

The calibration value is added to the tag's input value after the input has been scaled. It is used to fine tune the input to the correct value in conjunction with a known input reference. To decrease the value of the input, specify a negative calibration value.

Units 

Enter a text string or select from the supplied list to appear as the tags units. 

Sqr Root

Click this checkbox on to apply a square root filter to the tags value, the actual filter uses the tags Input Resolution to calculate the sqr root value.

BCD Prescale

Click this on to convert the tags value from a BCD number to a Binary value before the tags value is scaled to a real number. This is used when the data is stored within the PLC as BCD numbers.  

Prescaler

A built in math function that can be applied to scale the tags value.
Current Prescaler functions are shown in Prescaler Functions.

See Also

Type and Address
Scaling
Alarm
Alarm 1
Alarm 2
Totaliser
Retransmission
Digital Scaling
Psuedo Digital Scaling
Digital Alarm
Math Settings
Counter Scaling