Cryogenic Sensor Signal Conditioning Unit

Abstract

A cryogenic system including a source of cryogen fluid, a cryogenic chamber receiving the cryogen fluid to cool the cryogenic chamber, an exhaust for venting spent cryogen from the cryogenic chamber, a cryogenic sensor positioned in the cryogenic chamber to monitor a condition, and a cryogenic signal conditioning unit associated with the cryogenic sensor. The cryogenic signal conditioning unit includes a software programmable current source, a programmable gain amplifier, an analog to digital converter, a memory, and a user interface.

We claim: 
     
         1 . A cryogenic system comprising:
 a source of cryogen fluid;   a cryogenic chamber receiving the cryogen fluid to cool the cryogenic chamber;   an exhaust for venting spent cryogen from the cryogenic chamber;   a cryogenic sensor positioned in the cryogenic chamber to monitor a condition; and   a cryogenic signal conditioning unit associated with the cryogenic sensor and including
 a software programmable current source outputting an excitation current to the cryogenic sensor, 
 a programmable gain amplifier receiving a sensor output from the cryogenic sensor and amplifying the sensor output into an amplified output, 
 an analog to digital converter receiving and converting the amplified output, and outputting a data output, 
 a memory in communication with the software programmable current source, the analog to digital converter, and the programmable gain amplifier, and 
 a user interface in communication with the software programmable current source, the analog to digital converter, the programmable gain amplifier, and the memory, 
   wherein the user interface uses an industry standard communication protocol,   wherein the user interface communicates with the software programmable current source to set a value of the excitation current, and   wherein the data output is saved to the memory.   
     
     
         2 . The cryogenic system of  claim 1 , wherein the industry standard protocol is MODBUS. 
     
     
         3 . The cryogenic system of  claim 1 , wherein the industry standard protocol is Ethernet. 
     
     
         4 . The cryogenic system of  claim 1 , wherein the industry standard protocol is CAN. 
     
     
         5 . The cryogenic system of  claim 1 , wherein the communication with the user interface is provided over an RS485 connection. 
     
     
         6 . The cryogenic system of  claim 1 , wherein the software programmable current source sets the value of the excitation current between 0 mA and 200 mA. 
     
     
         7 . The cryogenic system of  claim 1 , wherein the software programmable current source sets the value of the excitation current based on an input at the user interface. 
     
     
         8 . The cryogenic system of  claim 1 , wherein the software programmable current source sets the value of the excitation current based on the type of cryogenic sensor connected to the system. 
     
     
         9 . The cryogenic system of  claim 8 , wherein the value of the excitation current is set according to a preset value corresponding to one of a temperature diode, a thermistor, a thermocouple, an RTD sensor, a hall sensor, and a pressure transducer. 
     
     
         10 . The cryogenic system of  claim 1 , wherein the analog to digital converter and the programmable gain amplifier provide a usable data output based on a sensor output from sub-mV to V levels. 
     
     
         11 . The cryogenic system of  claim 1 , further comprising a bus in communication with the software programmable current source, the analog to digital converter, the programmable gain amplifier, the memory, and the user interface, the industry standard communication protocol being communicated via the bus. 
     
     
         12 . The cryogenic system of  claim 11 , wherein the bus is configured to allow simple integration into data acquisition and control systems. 
     
     
         13 . The cryogenic system of  claim 1 , wherein cryogenic signal conditioning unit is arranged to receive an unconditioned sensor output from the cryogenic sensor. 
     
     
         14 . The cryogenic system of  claim 1 , further comprising a housing, the software programmable current source, the analog to digital converter, the programmable gain amplifier, and the memory positioned within the housing. 
     
     
         15 . The cryogenic system of  claim 14 , the housing configured to be DIN rail mounted. 
     
     
         16 . The cryogenic system of  claim 14 , the housing including a power bus, an excitation bus, a sensor bus, and an output bus. 
     
     
         17 . The cryogenic system of  claim 1 , wherein the cryogenic signal conditioning unit is configured to operate with the cryogenic sensor by positioning a jumper. 
     
     
         18 . The cryogenic system of  claim 1 , wherein the user interface is a personal computer, and wherein a user interacts with the user interface through a java interface. 
     
     
         19 . The cryogenic system of  claim 1 , further comprising a microcontroller in communication with the software programmable current source, the analog to digital converter, the programmable gain amplifier, the memory, and the user interface, the microcontroller coordinating operation thereof 
     
     
         20 . The cryogenic system of  claim 19 , further comprising a housing, the software programmable current source, the analog to digital converter, the programmable gain amplifier, the memory, and the microcontroller positioned within the housing.