Control.com - Nerds in Control

Dear All,

What would be the voltge resolution the PLC can read if the analog input resolution is 16 bit and the input range selected in 0 to 10 volts?

Approximately 10/16384 unipolar or 20/16384 if bipolar.

Regards

cww

The resolution would be 10 volts divided by 2 to the 16th power (0.00015 volts).

I'll bite.

6535.5 counts per volt.

Another student question?

16 bit = 0xffff = 65535 states
0-10 V is a 10 V span

10 V / 65535 states = 1.5259 x 10^-4 V/state

Davis Gentry

Hi,

David's answer is correct, but you should check with the manual as some modules just use -10 to +10 and then the Most Significant Bit is the signed bit and thereby in reality giving you only a 15 bit resolution. And then some will scale to an over voltage range, i.e. 0 to 10.5v. Cheers.

The above calculation will give you resolution but you should really look into the absolute accuracy of your measurement.

It is not because you are a resolution of 16-bit that your accuracy is 16-bits. You typically should find the accuracy in the user manual of you devices.

I know that NI Programmable Automation Controller (PAC - http://www.ni.com/pac/) will have that in their user guide.

You can also check out these online ressources:
Understanding Instrument Specifications -- How to Make Sense Out of the Jargon
http://zone.ni.com/devzone/cda/tut/p/id/4439


Meas urement Accuracy of a Data Acquisition Board
http://zone.ni.com/devzone/cda/tut/p/id/4517

Hope this helps,

Vincent Carpentier
Vincent.carpentier - at - ni.com
Quebec and Maritimes Field Sales for National Instruments

Hi,

In case of Siemens S7 IO cards, it is 361.7 uV/bit.

Regards,

Jacek Dobrowolski