Keithley SourceMeter 2460 User Manual page 60

Section 6: Rechargeable battery measurements
Send the following TSP commands for this example application:
--This code discharges a 2500 mAH 1.2 V battery to 0.9 V with a
--discharge current of 2.5A (1C).
--Before using this code, reset the instrument from the front panel
--and set the output-off state of the Model 2460 to High Impedance
--(High Z). Also, insert a USB flash drive in the front-panel USB
--port to save your readings.
--Clear the buffer.
defbuffer1.clear()
--Measurement settings.
smu.measure.func = smu.FUNC_DC_CURRENT
smu.measure.range = 2.5
smu.measure.sense = smu.SENSE_4WIRE
--Source settings.
smu.source.func = smu.FUNC_DC_VOLTAGE
smu.source.offmode = smu.OFFMODE_HIGHZ
smu.source.level = 0.9
smu.measure.terminals = smu.TERMINALS_REAR
smu.source.range = 0.9
smu.source.readback = smu.ON
smu.source.ilimit.level = 2.5
--Set the voltage limit for the battery to stop discharging.
--Set the variable for the number of iterations.
voltLimit = 0.9001
iteration = 1
--Turn on the source output.
smu.source.output = smu.ON
--Change the display to the USER swipe screen.
display.changescreen(display.SCREEN_USER_SWIPE)
--Keep taking readings in the while loop until the measured voltage
--is equal to the voltage limit.
while true do
--Take 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.
6-10
Model 2460 Interactive SourceMeter® Instrument User's Manual
2460-900-01 Rev. A / September 2014