NI 9263- NI9269 precision

[new_ingenieur]

Hello,

I have just one question . How the ni9263 and ni 9269 could have the same number of bits (n=16), the same level voltage (+/-10V) and a different precision (9263: 0.11V / 9269: 0.006V)?

I think that precision of signal depends on resolution and resolution =V/2^n. Now why the precision is different?

thanks

regards

[Henrik_Volkers]

You are talking about resolution 😄

Range does not have to equal the max ADC range 😉

Precision ?  What is pecision???   I usually talk about uncertaincy tied to a measurement 🙂

And uncertaincy usually is a function with a lot of (statistic) variables.

[new_ingenieur]

Hi ,

thanks for your answer.

And for precision , look at  the NI specification : http://sine.ni.com/nips/cds/view/p/lang/fr/nid/208806. We note that precision is egal to 0.11V.

thanks

[Henrik_Volkers · Accepted solution]

So you found out that the number of bits doesn't tell you all 🙂

The resolution of the DAC isn't all. It needs the DAC, a reference source (build-in or external), a supply and an amplifier, all build on a PCB in a housing.

Every part plays a role to the uncertaincy/precision, common main enemies are temperature, drift (over time and temperature), humidity ....  EMC/noise/....

And, no wonder.... one part is about twice the cost of the other.

You can buy a resistor for less than 1c or >1000 times that value ...  both migth have the resistance ... well, at a certain point ...

[new_ingenieur]

************************thanks for answer.Now it's very clear****************************

[new_ingenieur]

************************thanks for answer.Now it's very clear****************************

[new_ingenieur]

Normally i know that i must open a new topic for ask question. But i need this response very quickly it's a high importance.

Tell me if NI9263 could have an offset value? i buy it just one year ago and  i don't see 'offset' in specification.

I ask this question because i have ni 9263 + electronic circuit. On my output i have an offset .

thanks

[Henrik_Volkers]

on page 13 I see an offset error spec.

uncalibrated 1.7% of 21.4V ...   so you migth expect up to 364mV Offset in the temprange -40 to +70°C

Don't know this hardware... is there a autocal or selfcalibration button in MAX?

[new_ingenieur]

hi,

May be in max there are this button but i don't see them. But now What worried me , it's this value of offset .Its very high for my measure.

I have a signal of 220mV so offset egal to 364mV is very high for me.

Do you have tips for this?

regards

[Henrik_Volkers]

How about doing an offset cancelation befor starting your application?

Measure the offset and include that value in your setpoint?