User Manual

Differences Between Series A, Series B, Series C and Series D Thermocouple/MillivoltE–2
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Explanation of Differences
•
Calibration is now done automatically using auto–calibration
feature, or manually through programming.
• calibration is now done at 0.000mV and +100.000mV .
• If EEPROM read of the auto cal values fails, BTR WORD 1 bit 7
is asserted.
• Series A used potentiometers for calibration settings with
calibration done at –99 and +99mV.
• RTS can now be reduced to 100ms for all thermocouples by
programming RTS = 1.
• The default RTS setting (RTS = 0) makes data available every
50ms. Series A default value was 500ms.
• BTR WORD 12 is the rounded Cold Junction Temperature
resolute to 1 degree C displayable in the programmed format
(BCD, 2s complement or signed magnitude). In Series A, BTR
word 12 was the cold junction calibration word.
• BTW WORD 1 bit 7 is no longer used (cold junction
update).
• Cold Junction calibration by the user is no longer required; it is
calibrated at power up.
• Cold junction temperature is digitally filtered having a filter
time constant of 12.8 seconds. It is no longer updated once per 15
second interval.
• Cold junction value is updated continously in Series B. Update
was once every 15 seconds in Series A.
• Backplane power is approximately 750mA at 5V. Series A had a
backplane power requirement of 1200mA.