Microcontroller - 8051, 8052, OpCodes, Analog Interface.

Saturday, February 17, 2007

How to Use Your PC to Measure Temperature

Thermocouple, RTD, Temperature monitoring is central to the majority of data acquisition systems, be it to save energy costs, increase safety, reduce testing time...whatever your reasons, you will need a device to measure the temperature - a temperature sensor.

How to Use Your PC to Measure Temperature

Thermocouples, resistance temperature devices (RTDs), thermistors and infrared thermometers are all types of temperature sensor. Which you choose depends on factors like your expected maximum and minimum temperatures, the accuracy you need and your environmental conditions.

752-RTD: RTD Resistance Temperature Measurement, Digital I/O, Counting, Analog Output
  • Measure temperature using RTDs or Pt100 sensors, and voltage signals
  • With extra hardware monitor thermocouples and strain gauge bridges
  • Includes the powerful yet easy-to-use Windmill software for Windows: no programming required
  • Connect up to 8 USB units to one PC
Here is a way you can learn, How To Interface PC to the Outside World.

How to Use Your PC to Measure Temperature

Temperature Control with a PC

Based on the above the Octagon computes a sensible heating/cooling current value and transmits a corresponding analogue signal to the current control electronics in the TC-box.
The current control electronics control the current provided by a big external power supply flowing through the peltier heating elements according to the signal received from the Octagon.

delabs Notes

This is a project that will help students learn both hardware and software aspects of a control system. Here you can test out an automation program on a PC with minimum external hardware.

When you implement in the field, the system has to be a dedicated real time uC based product on custom firmware. Systems with OS + Software combination are not known to be reliable in Process Control. But OS + Software is good for Supervisory Systems which get their data from Real Time Controllers.

So a front end controller must be Rugged, Non-PC based and Non-OS based unit. This means use something like a SBC. With a Robust and Compact (means fast) firmware.

The firmware should be Polling or Interrupt based but with both internal and external watchdog. Most important a Power supply Management that resets system properly over Brown-outs and Black-outs. Even today some Embedded Systems i have to turn off and on after power resumes.

Don't Forget, Multiple Watch Dogs and Multiple Power Management for graceful start of system !! Use one big SuperCap if you want. Else people will go back to Thermostats.