### Author Topic: arduino measuring 4-20ma what kinda precision  (Read 10216 times)

0 Members and 1 Guest are viewing this topic.

#### XFDDesign

• Frequent Contributor
• Posts: 435
• Country:
##### Re: arduino measuring 4-20ma what kinda precision
« Reply #25 on: January 09, 2016, 01:27:15 pm »
So I’m think you want me to put some numbers on what I’m looking for ?

so in terms off precision assuming the sensor was 100% accurate something like 1data point / pr 1 cm  in other word 8meter - 0.4m(sensor dead zone) = 7.6 m = 760 data points

Since i'm no engineer just pure hobby the circuit design and calculation need to be simple and straight forward

If you want about 760 data points, then you're looking at a 10 bit converter (1024 counts).

So here is a simple question, have you hooked up a DMM in Ammeter mode to the supply line of this thing, and directly powered it from a DC supply? Can you confirm basic operation of the device by adjusting height and verifying a reading change on your DMM?

#### simondid

• Contributor
• Posts: 20
• Country:
##### Re: arduino measuring 4-20ma what kinda precision
« Reply #26 on: January 09, 2016, 01:34:16 pm »
Quote
So here is a simple question, have you hooked up a DMM in Ammeter mode to the supply line of this thing, and directly powered it from a DC supply? Can you confirm basic operation of the device by adjusting height and verifying a reading change on your DMM?

no i havent i don't have acces to a 14v+ power supply atm i goth one in order on ebay but you know like 30+ delivery

#### XFDDesign

• Frequent Contributor
• Posts: 435
• Country:
##### Re: arduino measuring 4-20ma what kinda precision
« Reply #27 on: January 11, 2016, 03:22:09 pm »
Quote
So here is a simple question, have you hooked up a DMM in Ammeter mode to the supply line of this thing, and directly powered it from a DC supply? Can you confirm basic operation of the device by adjusting height and verifying a reading change on your DMM?

no i havent i don't have acces to a 14v+ power supply atm i goth one in order on ebay but you know like 30+ delivery
Stack two 9V batteries in series?

#### Seekonk

• Super Contributor
• Posts: 1837
• Country:
##### Re: arduino measuring 4-20ma what kinda precision
« Reply #28 on: January 11, 2016, 03:47:10 pm »
Just going to more bits may not increase the accuracy.  Every instrument will have some drift and noise associated with it.  If this does measure distance  as said in the prior post, I doubt that it is that accurate or repeatable.  Distance measured with an analog signal is seldom accurate. 1000 data points should be about the limit for this kind of device.  The number of data points needed for the entire length should have been the first thing figured out.

Smf