USB-2416 Calibration Tolerances

[darod]

Hello,

 

I am calibrating Analog Input DC Voltage and Type K TC on a USB-2416. I am using the absolute accuracy for my tolerance, but I am observing out of spec measurements for the Analog Input DC Voltage even after performing the calibration in the software. Do you guys use other accuracies/specifications to verify this unit? (E.g. gain error, offset error, INL error, absolute accuracy, gain temperature coefficient & offset temperature coefficient combined?). I also noticed the user guide calls out for a 10V calibration reference with a +/- 5mV maximum accuracy.

 

Thanks

[DAQman]

The accuracy specifications are published in the back of the USB-2416 user manual. The device uses an LT1236 precision reference to generate the internal 10-volt reference, which produces references for all the ranges. If the reference is out of spec, it is adjusted when returned to the factory for calibration. If the voltage input is set to differential mode and your voltage calibrator has an isolated output, connect a reference resistor from the channel low to the ground. If the input is set to temperature, set the data rate to 60 Hz for best results.

 

[darod]

I am sourcing 10 V using a Fluke 5560A with the USB-2416 configured to the following:

1. Channel Type: Voltage
2. Input Mode: Differential
3. Range ±10V
4. Data rate: 3750 Hz

Per the accuracy specifications in the user manual, the measured value is supposed to be between 9.9995784 V & 10.0004216 V to be deemed within specification. Can you please confirm my understanding on the accuracy is correct. I am currently getting 9.9983 V.

[DAQman]

The absolute accuracy for the 10-volt range and the channel set to 3750 Hz data rate is +/- 421.600 µV. The measurement should fall within (9.9995784 - 10.0004216). You also must add the fluke 5560a errors.