SCXI-1125 Self Calibration

[Bojan]

HI,

What "DAQmx Self Calibrate.vi" performs when the device in is SCXI-1125 module?

Thank you

Bojan

[Kokosinela]

Hi, Bojan.

If you look at the palette on your block diagram in LV, which comes with instaling DAQmx drivers, you can find subpalete which has functions for self calibration.

One of those fuctions is DAQmx Self Calibrate.vi. This function measures the onboard reference voltage of the device and adjusts the self-calibration constants to account for any errors caused by short-term fluctuations in the operating environment. When you self-calibrate a device, no external signal connections are necessary.

Another function, which you can find on subpalette, is for example DAQmx Adjust SCXI  Calibration.vi . This function adjusts the external calibration constants for an SCXI module. The instances of this polymorphic VI correspond to the SCXI module you want to calibrate. Refer to the calibration procedure for your module for detailed calibration instructions. There is also DAQmx Setup SCXI  Calibration.vi. This function sets up calibration for SCXI modules. The instances of this polymorphic VI correspond to the SCXI module you want to calibrate. Refer to the calibration procedure for your module for detailed calibration instructions.

So, answer on your question is that DAQmx Self Calibrate.vi does things which are described in previous paragraph (calibration is done on DAQ device). It means that using this function, you have influence on your DAQ device. If you want to calibrate SCXI module, you will use another functions.

I hope that this answer will help you.

If you have more doupts, do not hesitate to ask.

Kind regards,

Sofija P.

[Bojan]

Hi,Sofija.

Thank you for your help, but I just want to perform offset calibration of the SCXI-1125 using DAQ device, LabVIEW and DAQmx driver and not the external gain calibration.

"The SCXI-1125 provides input switching that allows to programmatically shunt the differential input channels of the SCXI-1125. Once the channels are shunted, the channel can be read by a calibrated DAQ device

or calibrated DMM. These offsets voltages, read by the calibrated device, can be saved in the calibration EEPROM in the SCXI-1125 for software correction of offset."

(cited from SCXI-1125 User Manual, Chapter 5 Using the SCXI-1125, Calibration, pp. 5-30).

"To perform offset calibration on your module, follow this procedure if you are using LabVIEW:

1. Make sure the DAQ device or DMM you are using has a valid

calibration and meets the accuracy specifications for your application.

2. In LabVIEW, use the SCXI Calibrate VI to calibrate your module."

(cited from SCXI-1125 User Manual, Chapter 5 Using the SCXI-1125, One-Point Offset Calibration, pp. 5-31).

The problem is that SCXI Calibrate VI arrives from Traditional DAQ driver. What is the replacement for One-Point Offset Calibration with DAQmx driver ?

Thank you

Bojan