6485 data overflow

I'm a student working with the 6485 low-current test, continuous collection of 50 data, as long as there is an overflow, all the measurements will become large, if there is no overflow, 50 measurements are normal, why? Can someone help me?

Overflow is a condition where the input signal from the device under test exceeds the range or measurements capabilities of a particular instrument.
If you are encountering overflow, I would recommend increasing the range for that measurement to appropriately capture the desired reading.
If you find that overflow on a previous reading/channel is impacting the results recorded on a subsequent channel, I recommend checking the functionality of the channel against a known value (i.e. power supply static voltage source, resistor, etc).
If the channel is operating within specification, this may be an anomalous reaction to the overflow or could be due to a relative measurement configured via other settings of your test.
Can you elaborate on what you find when the values 'become large'?
This will help to better resolve the issue you're encountering. As much detail possible regarding your test, DUTs, settings and readings would be helpful.

Hello,
     the instrument is not set for relative measurement. Because the current of the tested device fluctuates greatly, and may even exceed the range of the instrument, there will eventually be overflow. Can I send instructions to solve the problem that the data overflow causes the reading to become larger. Can you help me? thank you！