DH Instruments MOLBOX ANALOG CIRCUIT, User Manual

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2. RUNNING A CALIBRATION
Page 3 © 1997-2002 DH Instruments, Inc.
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2.1 OVERVIEW
Before running a calibration, connect the 25 pin connector end of the calibration cable to the MFC port and the
other end to the voltage or current measuring channel of the multimeter. The red plug is positive voltage,
the black plug is negative voltage, the blue plug is positive current and the white plug negative current.
When performing a Voltage mode calibration only connect the Red and Black connectors to the
multimeter. Current (mA) calibrations should only have the blue and white connectors attached.
Leaving different mode connectors attached or letting any connectors come in contact during a
calibration could damage the molbox circuit.
2.2 CHECK CALIBRATION
The first step is to check to see if the calibration is out of specification. This is accomplished by selecting
a Voltage or Current mode Calibration Check from the Test menu (see Section 3.5). The software will set
two points, 5 and 0.5 V or 20 and 5 mA, without correcting with the molbox sense line. After each setting
a prompt on the status bar to enter the current multimeter reading displays. The area of input will
highlight and you must type in the multimeter reading and press return. The multimeter will only display
the proper value when you are prompted; so wait for the prompt before entering the reading.
It is important to make sure that the value is properly input into the text box as this will directly
affect the results of the calibration.
The agreement between the multimeter readings and those read back from the molbox must be less than
± 0.1 % full scale for set values and ± 0.05 % full scale for the measure values for molbox1. If this is the
case, the molbox1 is in tolerance and there are no other necessary steps. However, if the molbox is out
of tolerance then a recalibration is necessary.