PCI-4070 spec question

[JSflow]

DMM => PCI-4070
1) 카달로그에 나와있는 READING RATE는 전압을 기준으로 나와 있는것으로
알고 있습니다.. 그런데 저희는 저항의 값을 0 - 300옴 사이에 0.01옴의 오차를
요구하며, READING RATE가 1KS/s이상이면 합니다. 저항을 측정할 때도
전압과 같은 READIND RATE를 가지는지 확인 부탁드립니다.

2) 저항을 측정하는데 있어서 중간에 연결하는 CABLE이 조금 길어질수 도있는데
길이에 따른 저항 값의 오차는 어떻게 보상되는지? 오차는 얼마인지..?

Hello,

From the Data Sheet of 4070, I see it mentions the Reading Rate on DC and AC Voltage measurement.
However, I'd like to measure resistance in beteen 0-300 Ohm and require error +-0.01 Ohm.
IS there a reading rate on Resistance measurement?

Also, when measuring resistance, the cable could get longer at times. Will length change
the resistance value? If so, how do I compensate?

Thanks

[RossC]

JSFlow,

The DC reading rates in the NI 4070/4072 Specifications on page 1 apply to resistance measurements. 300 Ohms would require you to set the DMM to the 1 kohm range. To get accuracy down to +/- 0.01 ohms in the 1 kohm range, you would need to use 6 1/2 digit resolution, since you need accuracy down to the 6th digit of the selected range.

In addition, if you are concerned about cable length compensation when doing your measurement, you should use 4-wire resistance measurement mode, as this mode compensates for errors due to cable length.

Sincerely,

Ross C
Applications Engineer