Data acquisition apparatus

Data acquisition apparatus for transferring signals produced by a thermocouple to input circuitry while maintaining electrical isolation between said thermocouple and said input circuitry, said data acquisition apparatus comprising:

• first means for temporarily storing said signals,
• second means for temporarily storing said signals,
• first means operable to transfer signals from said thermocouple to said first storage means,
• second means operable to transfer signals from said first storage means to second storage means,
• means for alternately operating said first transferring means and said second transferring means in a continuous sequence,
• third means responsive to control signals produced by said input circuitry for transferring signals stored in said second storage means to said input circuitry, and
• means for detecting a break in said thermocouple comprising:
• a voltage source and
• an impedance connecting said voltage source to said second storage means;
• the value of said impedance being high relative to the value of the impedance of said thermocouple.

Data acquisition apparatus for transferring signals produced by a sensing element to input circuitry while maintaining electrical isolation between said sensing element and said input circuitry, said data acquisition apparatus comprising:

• a first sample-and-hold capacitor,
• a second sample-and-hold capacitor,
• first semi-conductive means connecting said first sample-and-hold capacitor to said sensing element,
• second semi-conductive means connecting said first sample-and-hold capacitor to said second sample-and-hold capacitor, and
• free-running oscillator means for alternately operating said first and second semi-conductive means in a continuous process to alternately connect said first sample-and-hold capacitor to said sensing element and said second sample-and-hold capacitor.

Data acquisition apparatus for transferring signals produced by a thermocouple to computer input circuitry while maintaining electrical isolation between said thermocouple and said input circuitry, said data acquisition apparatus comprising:

• a capacitor connected across said thermocouple for receiving said signals,
• a first sample-and-hold capacitor for temporarily storing said signals,
• a second sample-and-hold capacitor for temporarily storing said signals,
• a first pair of optical isolator elements connected to said capacitor and said first sample-and-hold capacitor and operable to transfer signals on said capacitor to said first sample-and-hold capacitor,
• a second pair of optical isolator elements connected to said first sample-and-hold capacitor and said second sample-and-hold capacitor and operable to transfer signals on said first sample-and-hold capacitor to said second sample-and-hold capacitor,
• a free-running squarewave oscillator,
• a divide-by-four counter responsive to the output of said free-running oscillator for generating sequentially four output signals,
• a first FET switch responsive to one of said divide-by-four counter outputs for operating said first pair of optical isolator elements to connect said thermocouple to said first sample-and-hold capacitor,
• a second FET switch responsive to another of said divide-by-four counter outputs for operating said second pair of optical isolator elements to connect said first sample-and-hold capacitor to said second sample-and-hold capacitor, and
• a multiplexer responsive to control signals produced by said input circuitry for transferring signals stored in said second sample-and-hold capacitor to said input circuitry.