edwin001

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  1. Cristian, So, what you are saying is that without user calibration, the Shield will not produce reading accurate to + - 0.1%. If I need to calibrate, do I have to calibrate ALL the various ranges? I want to be able to use the meter to measure any parameter within its capability.
  2. Bianca, I also measured the current using CurrentDC50m and got -5.019mA +4.973mA using factory calibration only.
  3. Bianca, Technically speaking, the Shield should have no issues measuring 200m in the 5A range since the HY3131 chip has a 50,000 count to yield a step resolution of 5/50,000=0.0001A or 100uA. If, however, I was trying to measure 200.06mA then it totally makes sense to dial down to the 500mA range to give myself a step resolution of 0.01mA or 10uA. If I don't have to use the lower range to get current measurement, then that would be best in order to avoid the loading effect associated with the shunt resistor (ie 0.02 ohms in the 5A range vs 1 ohm in the 500mA range). Here are some measurements as you requested where I used CurrentDC5m and VoltageDC5 for the ranges. Factory Calibration Only: 4.714mA -4.9975V +5.0064 After using User Calibration: 4.991mA -5.0025V +5.0034V Standard using Hioki DT4282 DMM having + - 0.025% accuracy: 4.992mA -5.0029V +5.0030V
  4. Cristian, Here are the answers to your questions: 1. Using the DMMShieldDemo_BasicCmds sketch, I can send DMMRestoreFactCalibs within the Serial Monitor and see the board respond with the message: COMMAND: DMMRestoreFactCalibs Calibration data restored from FACTORY EPROM 2. Further playing with the system, I was able to get the board to user calibration using DMMSaveEPROM. I had to cease to the repetitive measurements and only perform calibration measurements to a reference followed by saving the results to user EPROM. I am using an Arduino Mega board. It is odd that after providing all 3 measurements for calibration, the system fails to display a Coeff factor. I have captured this message for you here:
  5. JColvin, Was you able to get any ansnwers?
  6. Can you provide examples of calibrating using Arduino. I used DMMCalibP, DMMCalibN, and DMMCalibZ to calibrate VoltageDC5 range. When I issued DMMSaveEPROM command, nothing was saved. Also, no difference in measurement results from using Factory calibration (using DMMRestoreFactCalibs) and after user calibration (using DMMCalibP, DMMCalibN, and DMMCalibZ and a reference of +-5.002900).
  7. Hello JColvin, Regarding performance accuracy stated in the documentation, are they achievable with factory calibration alone? OR are those specs only achievable when the user calibrates also? For calibration, does the user have to calibrate for all 4 voltage ranges, all 7 resistance ranges, and all 5 current ranges?
  8. Documents for the DMM Shield states an accuracy of +-0.1% for voltage, current, and resistance except for specific ranges highlighted. Is this accuracy obtained with factory calibration only OR does the user need to also need to calibrate the equipment? If the user needs to calibrate, can the calibration factors be stored and used by Shield OR is a external program required to make adjustment in real time. At the moment, the Shield fails to produce comparable measurement with a Fluke 88V that has lower accuracy for current and resistance readings. For the voltage readings, the accuracies are comparable but the Shields gives a poor reading based on calculated values vs measured.