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General => Technical support => Topic started by: Tito on August 20, 2012, 08:56:50 AM

Title: ADC simulation
Post by: Tito on August 20, 2012, 08:56:50 AM

Hi I do try out ADC function by using variable resistor 5K.
I just assume this

Temp C          Voltage         ADC
-20C               0                  0
+200C            5                  4096

By linear relationship
(T+20)/(200 +20) =(A-0)/(4096-0)
T = (A/4096)*220 - 20

while try with value A=0 , i do get T = -20C and when A=4096 then T = 200C. mathematically correct

In my custom function i do wrote as
B = ADC(1) *220 - 20

When i do adjust the variable to minimum end, do get -20C but in maximum end i do get 900C instead of 220C. May i know what cause the error. Thanks

Title: Re:ADC simulation
Post by: support on August 20, 2012, 11:27:53 AM

You B formula is incorrect:

B = ADC(1) *220/4096 - 20

Title: Re:ADC simulation
Post by: Tito on August 20, 2012, 09:42:48 PM

 ;) Cheers

Title: Re:ADC simulation
Post by: Tito on August 22, 2012, 08:28:45 PM

Hi, I am using 5K variable resistor to simulate height of water level from 0 to 10 m

A = ADC(1)*10/4096
SETLCD 1,1,"Wtr Level = "+STR$(A)+ " m"

my intention is to display in LCD with 2 decimal place. Is that possible? Currently its just display in integer format.

Title: Re:ADC simulation
Post by: support on August 23, 2012, 02:07:37 PM

Please refer to this thread:

http://www.tri-plc.com/yabbse/index.php?board=2;action=display;threadid=1084

Title: Re:ADC simulation
Post by: Tito on August 24, 2012, 08:12:23 PM

Superb, thank you.

A = ADC(1)*1000/4096 'changed from 10 to 1000
SETLCD 1,1,"Wtr Level = "+STR$(A/100) +"."+STR$(A mod 100,2)+ " m"