program offered by national instruments stores and displays the data alarms may be generated based on defined settings and limits and central computer 12 may be either configured to initiate the data communication or to respond to data requests initiated at central computer 12 or both information from the hmi software may also be linked to spreadsheets and database software to summarize information in tabular and graphical form information from the hmi software also may be automatically uploaded to the internet for easy access in another example and referring to fig3 sensing device 35 determines a material quantity within storage vessel 15 and transmits a signal that is representative of that measured material quantity to a data collection display unit 42 data collection display unit 42 outputs a signal indicating material quantity and transmits that signal to central computer 12 in this embodiment functions performed by rtu 16 are physically incorporated within data collection display unit 42 the signal generated by data collection display unit 42 can be transmitted over telephone radio or other communication means 40 also data collection display unit 42 may be either configured to initiate the data communication or to respond to data requests initiated at central computer 12 or both in yet a further example and refering to fig4 sensing device 35 determines a material quantity within storage vessel 15 and transmits a signal that is representative of that measured material quantity to an on site computer system 45 on site computer system 45 outputs an analog signal that is proportional to the measured material quantity and transmits that signal to an rtu 16 rtu 16 transmits a signal indicating material quantity to central computer 12 over telephone radio or other communication means 40 in.