Tektronix Keithley SourceMeter 2450 User Manual page 89

Model 2450 SourceMeter® Instrument User's Manual
-- Change the display to the USER swipe screen.
display.changescreen(display.SCREEN_USER_SWIPE)
-- Keep making readings in the while loop until the measured voltage
-- is equal to the voltage limit.
while true do
-- Make a reading and get the current, voltage, and relative timestamp.
curr = smu.measure.read(defbuffer1)
volt = defbuffer1.sourcevalues[iteration]
time = defbuffer1.relativetimestamps[iteration]
hours = time/3600
-- Compare the measured voltage to the voltage limit.
-- Exit the loop if it has reached the limit.
if volt <= voltLimit then
break
end
-- Print the number of completed cycles, the voltage, and the time for the
-- iteration. Display the information on the front panel.
print("Completed Cycles: ", iteration, "Voltage: ", volt, "Time: ", time)
display.settext(display.TEXT1, string.format("Voltage = %.4fV", volt))
display.settext(display.TEXT2, string.format("Current = %.2fA, Time = %.2fHrs",
curr, hours))
-- Increment the number of iterations and wait 10 seconds.
iteration = iteration + 1
delay(10)
end
-- Turn the output off when the voltage limit is reached.
smu.source.output = smu.OFF
-- Save the measurements to the USB flash drive.
FileNumber = file.open("/usb1/TestData.csv", file.MODE_WRITE)
file.write(FileNumber,"Current,Voltage,Seconds\n")
-- Print the measured values in a four-column format.
print("\nIteration:\tCurrent:\tVoltage:\tTime:\n")
for i = 1, defbuffer1.n do
print(i, defbuffer1[i], defbuffer1.sourcevalues[i],
defbuffer1.relativetimestamps[i])
file.write(FileNumber, string.format("%g,%g, %g\r\n",defbuffer1.readings[i],
defbuffer1.sourcevalues[i],defbuffer1.relativetimestamps[i]))
end
-- Close the .csv file.
file.close(FileNumber)
2450-900-01 Rev. E / August 2019
Section 8: Rechargeable battery measurements
8-11