and observing what happens. It may be that the sample can still be measured
but it is necessary to note that:
1) The voltage may take a period of a few seconds, up to a couple of
minutes, to reach the voltage to be measured. In this case the ‘peak’
voltage should be noted.
2) The unit may need to be set to Low sensitivity. This is the case if the
RM3000 displays ‘Out of Range’ rather than ‘Contact Limit’. If the
measurement still cannot be made but ‘Out of Range’ is displayed it is
possible to measure the voltage using an external voltmeter plugged
into the rear of the RM3000 (this is where the voltage exceeds 1.2V).
Error Messages
During attempting a reading several error messages are possible instead of a
reading.
“Out of Range” indicates that the reading exceeds the maximum input of the
in-built DVM. Reduce the current or the sensitivity of the internal DVM, or
use an external DVM.
“Contact Limit” indicates that the automatic compliance voltage has been
reached due to contact resistance or too much current, try reducing the
current
“Illegal Current” indicates that the set current is outside the normal 10nA to
99.999mA range. Set a new current.
“Calibration Error” indicates an error in the factory calibration
Calibration / Self Calibration
The overall calibration of the current source is carried by potentiometer
adjustment. The internal DVM has no calibration potentiometers; its
calibration is carried out in the factory. This can be recalibrated if required.
If the calibration factor is outside certain limits or has become corrupted
‘Calibration Error’ is displayed.
A separate internal DVM calibration occurs at power up. It recalibrates
against an internal reference at power up and when changing from Low to
High sensitivity, or vice versa. Zeroing also occurs at this time.
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