Datasheet Mass Flow Meter EM1 for Gases - Sensirion - #9

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CMOSens® EM1 Mass Flow Meter for Gases 3.2 Measurement frequency vs. resolution There is a trade-off between resolution and measurement time. Possible settings are listed in Table 7. Choosing 12 bit results in a measurement interval of 80 ms. With the max resolution of 15 bit, a new measurement is provided every 640 ms. Table 7: Resolution settings using the res=value command and corresponding response times 3.3 Measurement Strategy As mentioned in paragraph 3.1 (Important Notes) excessive EEPROM write cycles should be avoided. Sensirion therefore recommends to use the EM1 in PUSH-mode strategy: The EM1 is set to constant measurement mode and is pushing a new measurement once it becomes available. Check Table 7 for the update rate (data rate). When using the EM1 in GET-mode strategy a measurement is started after the GET command only. At each GET command the same EEPROM memory cells are rewritten. res= Resolution [bit] Internal signal integration time [ms] Data rate [Hz] 0 8 5 200 1 9 10 100 2 10 20 50 3 11 40 25 4 12 80 12.5 5 13 160 6.25 6 14 320 3.125 7 15 640 1 1.56 Table 8: Error Codes Error Code Description Notes ERROR 01 Invalid command ERROR02 Wrong syntax ERROR 03 Value out of range ERROR 04 Not allowed mode ERROR 05 No permission ERROR 06 No permission ERROR 50 Invalid EEPROM ERROR 99 Internal error www.sensirion.com Data Sheet EM1 - v3.0 /March 2009 9 / 14