Watlow CAS - Manual (Page 87)

Appendix: Linear Scaling Examples
CAS User’s Guide 77
Example 3
Situation
A pulse encoder which measures the movement of a conveyor is
connected to the CAS. The encoder generates 900 pulses for every inch
the conveyor moves. You want to measure conveyor speed in feet per
minute (f/m).
Setup
The encoder input is connected to the pulse input. An one second
sample time gives adequate resolution of the conveyor's speed.
The resolution is:
so a display format of -99.99 to +300.00 is appropriate.
The input readings are as follows.
At the maximum pulse rate of the CAS (2000 Hz):
At zero hertz, the input reading will be 0.00 f/m.
Therefore, the scaling values are:
Parameter Low Value High Value
Process Value (PV) 0 f/m 1.11 f/m
Input Reading (RDG) 0 Hz 2000 Hz
1 pulse
1 ond sec
---------------------
60 onds sec
1minute
---------------------------
1 inch
900pulses
--------------------------
Ч Ч
1 foot
12inches
-----------------------
×
0.006 f m
⁄
=
200pulses
1 ond sec
--------------------------
60 onds sec
1minute
---------------------------
1 inch
900pulses
-------------------------- Ч Ч
1 foot
12inches
----------------------- × 11.11 f m ⁄ =