11... APPENDIX C: HYPERWARE FILE LISTING
High Speed Thermocouple Application:
In some applications, maximum speed of thermocouple measurement is desired. The Thermocouple icon is one of the slowest to process in a Program Net due to the intensive math associated with each sample. A Cold Junction Compensation reading is required as well as the thermocouple reading, then the two are combined through curve approximating polynomials... heavy math for the
A method to improve on the throughput rate of thermocouple inputs exists. If the thermocouple inputs are read as mV signals (which are processsed very quickly) and the CJC is read as a resistance (which is lots faster than temperature), the net will process many times faster. The mV readings from the Thermocouple icon and the resistance reading from the CJC icon are then merged in a
The following Program Net represents an application of this method of high speed thermocouple temperature data collection. Temperature rise data on components within an automobile brake is desired. Thermocouples are installed and connected to
A unique triggering scheme is implemented with the Event icon and three Sample Rate Clocks. One Sample Rate Clock causes the Event icon to sample the status of a switch connected to the brake pedal every 10mS. When the switch is open (ie brakes NOT activated) the CJC icon is enabled and the Sample Rate Clock sends a reading to memory every second. Additionally,. the 50mS Sample Rate Clock is sampling at its primary rate which is set to 1 second.
When the brake pedal is depressed, the CJC icon is disabled and the 50mS Sample Rate Clock driving the three Voltage icons (thermocouple inputs) switches to its Alternate rate, storing readings to memory every 50mS.
After the data has been collected and downloaded to the PC, a
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