Annex A; 301Adi/420Mdbs Technical Bulletin; Reading Value Scale Formulas - Honeywell IAQPoint2 Guide De Démarrage Rapide

301ADI/420MDBS Technical Bulletin

Reading Value Scale Formulas

When used with the 301ADI and the 420MDBS, the 301C menu "Scale"
option (within the Tx Info menu) allows users to scale their 4-20 mA
signal to more practical reading values. This menu also allows the
system to display values below 4mA (for non-standard devices that
operate on a 0 - 20 mA range).
The Scale menu option is composed of two screens that let you set
specific data for your scale conversion: Min, Max, (scaling) factor and
Units (of measurement):
Max
Min
The basic Engineering Unit* conversion formula for standard 4-20 mA
devices is:
(loop current - 4 mA) x (range maximum - range minimum) + range minimum
20 mA - 4 mA) x (specified factor)
Here are two examples of the scale conversion formula:
Example 1: (12 mA - 4 mA) x (1000 ppm - 0 ppm) +
Example 1 result = 500 ppm
Example 2: (12 mA - 4 mA) x (+500ºC - -200ºC) +
Example 2 result = 15.0 ºC
Note: In the example 2, the range is multiplied by a factor of 10, which allows
you to obtain a range of +50.0ºC to
decimal point.
*Engineering units represent the following measurement types: %, ppm, ºC, ºF
and RH.
510846
4/07

Annex A

1. Tx Info 001
-Scale(1)-
00250
00000
(20 mA - 4 mA) x 1
(20 mA - 4 mA) x 10
301ADI User Manual
Honeywell
301ADI/420MDBS Technical Bulletin
1. Tx Info
- Scale(2)-
Factor 00001
Units ppm
-
20.0ºC with a precision of one
Annex A
001
specified factor
0 ppm
1
-
200ºC
10
23