Smithco Envizio Pro Installation & Operation Manual - Manual (Page 187)

Manual No. 016-0171-148 177
Calculating the Calibration Values
Adjusting for Additional Magnets
Typically, four magnets are used with the wheel drive speed sensor. However, to ensure accurate speed
readings for large tires and very low speed applications, additional wheel magnets may be necessary. Any
even number of magnets may be used as long as they are of alternating color and equally spaced. After
calculating the speed cal, this number must be adjusted according to the number of magnets installed using
the following formula:
where ADJ = Adjusted Speed Cal, NM = Number of Magnets used and D = the Distance Measured.
For Example:
The distance measured between starting and stopping marks is 1200 and six magnets are installed.
The Adjusted Speed Cal is 800.
Speedometer Drive Speed Sensor
1. In the System menu, touch the Product Control icon and then select Speed. Touch the Distance button and
use the keypad to enter “0” as the distance displayed on the field computer.
2. Touch the Speed Cal button and use the keypad to enter a speed cal value of 612 [155].
3. Drive 1 mile [1 km]. The field computer will measure the distance driven using the speed cal value of 612.
Note:
Accelerate and decelerate slowly. To achieve the most accurate calibration, do not use the
vehicle odometer or the field computer distance display to measure the actual distance driven.
Use section lines or highway markers to determine the actual distance.
4. Touch the Distance button.
a. The field computer odometer should display a value of approximately 5280 [1000]. If it reads between
5200-5350 [990-1010], the speed cal for the vehicle is 612 [155].
b. If the field computer odometer displays any other value, perform the following calculation:
where OSC = Old Speed Cal, DA = Actual Distance travelled, Do = the field computer odometer
Distance and CSC = the Corrected Speed Cal. Round to the nearest whole number.
For Example:
Speed Cal = 612 [155]
Actual Distance = 5280 [1000]
Field computer odometer reading = 5000 [980]
English Units:
Metric Units:
The Corrected Speed Cal value is 646 [158].
4
NM
--------- D
×
ADJ =
4
6
--- 1200
×
800 =
OSC D
A
×
D
o
------------------------- CSC =
612 5280
×
5000
--------------------------- 646.3 =
155
[ ]
1000
[ ] ×
980
[ ]
------------------------------------- 158.1
[ ]
=