Analog Calibration

The IOBoard you will be using may require calibration.  Your instructor will tell you if this is needed. Calibrating the IOBoard requires close attention to detail but it is not hard to do.  The only instrument you’ll need is a digital multimeter.
Figure 1 below is the arrangement of the connections on the IOBoard. Calibration requires measuring and adjusting voltages at some of the terminals and then using these output ports to automatically calibrate the input ports. 


The initial calibration sets the Gain and the Offset of AWG1 and then repeats the procedure for AWG2:
1. Close any instruments that are on your screen. 
2. Launch Analog I/O. 
3. Connect your digital multimeter to the AWG1 terminal and its ground.  See Fig. 1. 
4. Set Analog I/O’s Analog Out Ch1 to 3.000 V. 
5. Select Device –> Analog Calibration. 
6. In “calibration settings,” select “channel 1.”  (It probably is already.) 
7. On the “AWG output” line, adjust “Gain” to get the dmm to read 3.000. 
8. Change Analog Out Ch1 to –3.000 V. 
9. Note the dmm’s reading.  Calculate the mean value between this number and –3.000.  For example, if the reading is –3.227, the mean value is –3.114 V. 
10. On the “AWG Output” line, adjust “Offset (SE)” to get the dmm to read the value just calculated. 
11. On the “AWG output” line, adjust “Gain” to get the dmm to read –3.000 V. 
12. Change Analog Out Ch1 to +3.000 V. 
13. Check the dmm, which should read 3.000 V.  If it doesn’t, split the difference and return to Step 7. 
14. Repeat Steps 3 through 13 for AWG2 with the following differences: 
     a. Connect the dmm to AWG2 and its ground. 
     b. Set Analog I/O’s Analog Out Ch2 as directed. 
     c. Make all calibration adjustments on “channel 2.”
This completes the manual calibration of the outputs.  

Now we’ll have Mobile Studio automatically calibrate the inputs A1+/– and A2 +/–. 
1. Close Analog I/O. 
2. Connect AWG1 to A1+ and AWG1’s ground to A1–.  (See Fig. 1.) 
3. Connect AWG2 to A2+ and AWG2’s ground to A2–. 
4. Near the bottom of the Analog Calibration screen,click the “auto-calibrate A1” button.  Calibration could take as long as a minute. 
5. Similarly, click the “auto-calibrate A2” button. 

That does it!  All of the instruments are calibrated.

Text and image courtesy of Dr. William J. Eccles, Rose-Hulman Institute of Technology.
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