Monarch Instrument DC1250 User Manual
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range it's a derived from. This usually affects only the input type
category selected for the current channel.
CAL ALL
Calibrate Nominal All - will reset all correction values for all input types
on both channels when selected from any input type and channel, a
sort of master reset. This is the default in the event that calibration data
is found to be corrupted in the non-volatile memory.
5.3.1 Basic Calibration
All calibration values are derived from a couple of key calibration points. Thereafter, any
fine-tuning done to a specific input on a channel is saved for that channel and input
range only. The key calibration constants are for:
Lo Volts
covering the 250mV, 1.25V, 2.50V ranges and should be
done on the 250mV range
– each channel
Hi Volts
covering the 5.00V, 12.5V, 25.0V ranges and should be
done on the 5.00V range
– each channel
THERMOCOUPLES
which are derived from the Lo Volts calibration value require
an additional offset to compensate for the ambient
temperature sensor
– each channel
RTDs
which are derived from Lo Volts calibration value require an
additional span calibration to correct for the internal current
source
– each channel
CURRENTS
which are derived from the Hi Volts calibration value require
an additional span calibration to correct for the external
resistor (Customer supplied)
– each channel
FREQ and SPEED
requires only a time base calibration shared for both
channels
In general, to calibrate an analog input, first set the specific channel to an input type in
the ADVANCED SETUP MENU - CHANNEL SETUP - INPUT TYPE (see Section 4.1).
Once an input type has been chosen, select CALIBRATION (see Section 4.1). Do not
change the units from the default values set when that range is selected (i.e. leave volts
as volts and current as current).
Apply a "zero" value to the input and using the up (▲) and down (▼) arrow buttons
adjust the OFFSET until the onscreen indications shows zero.
Apply a "high" value to the same input and using the up (▲) and down (▼) arrow
buttons adjust the SPAN until the onscreen indication agrees with the input (Note
– use
an input value slightly less than the full scale value to prevent an overrange indication).
Repeat for all input types and channels to be used, if not all of them.
5.3.2 Examples
Volts: Should be done for the Lo Volts - 250mV, 1.25V, 2.50V ranges, and Hi Volts -
5.00V, 12.5V, 25.0V ranges using the 250mV and 5.00 volt ranges respectively. For
each channel individually, set the input for 250mV and go to Calibration. Short the input
and adjust the OFFSET until 0 is indicated. Then apply a near full scale input (so as to
not over range the input, say 240 mV on the 250 mV range) and adjust the SPAN.