DC input ranges for NI -9225 and NI-9227

[faisaldin]

Hi Everyone,

I am very much confused about the DC input voltage and currrent ranges for NI-9225 and NI-9227 respectively. Plz help me out, I cant find them in the specifications.

Regards

[PackersFan]

9225  ->  -300V - +300V

9227  ->  -5Arms - +5Arms

All found on the specifications tab.

[faisaldin]

Thanks Chris for your reply,

I find it hard to understand datasheet or specifications for the above mentionned analog input modules.....

For example:

There is no such information provided for input voltage ranges for current sensing module NI-9227 that what is the maximum voltage signal line that can be applied to the module.

Secondly, as you mentioned that DC input current range for NI-9227 is -5Arms - +5Arms but the datasheet says 14 A peak. while if we convert 5Arms to its peak (5 x 1.414) we get current peak of 7.07 A. Its very ambigious and i cant understand the difference in specifications.

Regards

[KatieC]

Faisaldin, 

The NI 9227 is a current input module, so there are no input voltage ranges as this module does not support voltage inputs. 

As to your second question on the NI 9227 and the current range: Arms = 14/sqrt(2) is about ten. The total range would be 10Arms. The difference between -5Arms and +5Arms is 10Arms. Does this help clarify this specification?

Katie

[faisaldin]

Katie,

Thanks for your kind reply...... your answer clearifies the specifiation for current input .......

But Katie as you mentioned that NI 9227 is current module , so it does not require input voltage range....Question arises here that ..... for example let i have 2 type of input signals one of 100 VDC and 10A and the other one 440VAC and 5Arms in both cases the current is within the specified range now plz tell me that Is module is capable of measuring both curents or not????

One thing more i have learned from operating instruction and specification document page # 8....... is that the current sensing is basically a voltage measurement across shunt resistor and then it is conditioned, buffered and sampled by ADC...... so the realtion ( I= V/R) gives a resultant curent...... then im once again confused that if ADC is basically sampling voltage across shunt then why dont the module need input voltage ranges.........

plz reply me .........

Regards, 

[Carisa_L]

Hi faisaldin,

According to page 22 of the 9227 User Manual, the max voltage we recommend for safety is 250 Vrms. You would be able to measure the first signal you described, but not the second with effective channel isolation. Hope this helps!

Best,

Carisa

[TTP38]

Hi,

I would like to mesure current with a range of 0 - 250 mA. The NI9227 can mesure this range with an accuracy of at least 0.01 mA? Thanks and good day.

TTP38.

[Case_in_Point]

Hi TTP38,

This thread hasn't had a post in over four years. You're much more likely to have people see your posts if you post on more current/active threads. 

As to your spec question, you can see the accuracy specs in the user manual: http://www.ni.com/pdf/manuals/375101e.pdf, page 19. The typical offset error alone is 0.05% of the full range, which is 5 Arms (7.07 peak), which goes beyond your 0.01 mA requirement. The 9227 is much more geared towards higher current measurements.

Cason

Applications Engr., NI

[TTP38]

Hi Cason_Point,

Thanks for your response and your advise.

I was thinking that the measurement depend only of the ADC resolution (24

 bit) and the Input noise (400µArms).

So the NI9227 has an accuracy of 2.5 mA thus it is not adapted for my measurements. I searched lot of NI current acquisition module for CompactDAQ (http://ohm.ni.com/advisors/compactdaq/pages/common/compare2.xhtml?conversationContext=2) but I did not manage to find the current acquisition module for my measurement. Do you know one current acquisitition module that which would correspond to my need? Thanks and good day.

Best regards,

TTP38.

[eltico]

Hi TTP38,

There isn't a device with that specific range, I suggest you get a conditioning stage to either amplify the signal and use the NI 9227 or decrease the signal enough to use any of the ±20 mA/ ±25mA range devices.