User guide

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Thermocouples: (preferred method) First calibrate lo VOLTS range (250mV) for the
same channel as described above. Then switch to Thermocouple range. Select
NOMINAL to copy the volts calibration to thermocouple range. The recorder is now
calibrated for ideal sensors. Refine the calibration by either shorting the input (you need
to know the ambient temperature) or attaching a thermocouple sensor or calibrator of
the correct type for the selected range, and then if necessary, adjust the OFFSET until
the correct temperature is displayed – this corrects the ambient temperature sensor. If
there's a known "high" temperature source handy use that to fine-tune the SPAN value.
Currents: (preferred method) First calibrate Hi VOLTS range (5.00V) for the same
channel as described above. Then switch to any CURRENT range. Select NOMINAL to
copy the volts calibration to the current range. The recorder is now calibrated for ideal
resistor (250 ohm). Refine calibration for resistor and sensor current tolerances by
attaching a 250 ohm +0.1% resistor and input sensor matching the selected range.
Apply low value inputs to adjust the OFFSET value, and high value inputs to adjust the
SPAN value.
RTDs: (preferred method) First calibrate lo VOLTS range (250mV) for the same
channel as described above. Then switch to RTD range. Select NOMINAL to copy the
volts calibration to RTD range. The recorder is now calibrated for ideal sensors and
internal current source. Refine the calibration by applying an accurately known
resistance for a given temperature (you may need resistance to RTD tables). Adjust the
SPAN until the correct temperature is displayed – this corrects for the internal current
source.
Frequency (RPM or Hz): Apply a calibrated frequency input near the high end of the
selected input range of either channel. Adjust SPAN until the indicated value is correct.
There is no applicable OFFSET adjustment to be made.
Recommended procedure for full initial calibration, in this order:
- Calibrate 250 mV range, both channels using a calibrated source.
- Calibrate 5.00 V range, both channels using a calibrated source
- Calibrate any T/C range, both channels using the NOMINAL method.
- Calibrate any RTD range, both channels using NOMINAL method
- Calibrate any current range, both channels using NOMINAL method
- Calibrate any Tach range, either channel using a calibrated signal source.
NOTES:
As with other numeric editing, the rate that a calibration value is adjusted accelerates
with the length of time the button is pressed.
Calibrating either channel for tachometry calibrates both channels and does not have to
be repeated for each channel as they use the same base counter. Additionally there's
no OFFSET adjustment for these inputs.
Thermocouple and RTD linearization tables are very accurate; usually calibrating the
250mV range for the same channel and then copying the calibration values using
NOMINAL should be enough. Remaining sources of error are the ambient sensor
(probably small) for the thermocouple and the current source (small) for the RTD, and
the actual sensors themselves. The ambient sensor can be calibrated by adjusting the
OFFSET with the thermocouple at some known temperature (such as ice water) or a
known room temperature with a wire short on the input. The input sensor span
adjustment would need a high temperature point to calibrate.
There can be interaction between the OFFSET and SPAN with the thermocouple input
since it can't be easily determined when exactly 0 volts is applied in combination from
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