130-28176 Parallax Inc, 130-28176 Datasheet - Page 218

• Manufacturer Part Number: 130-28176
• Description: KIT PARTS PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 130-28176

• Accessory Type: Education Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Board of Education Full Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Now it is time to complete the testing operation:
Ready to test your process control skills?
Figure 6-20 is a screen capture of our testing. The system has a fairly slow response.
Note that the dynamics are not that of a first order system on heating.
components of the system come into play. The heater requires time to come up to
temperature. This heat must be transferred to the air, and then transferred to the LM34.
On cooling, residual heat from the resistor must be dissipated, and energy of the system is
lost through the test tube walls in addition to the LM34 giving up its stored heat.
With manual temperature control of the system, it wasn't real easy to maintain it at 120
°F. There was lag time in response, causing overshooting and undershooting of the target
setpoint, making control difficult. After a while, and with practice, the user can become
accustomed to the system response and gauge more easily the control amounts needed. If
you were like us, shortly your concentration drifts and control becomes erratic. Precise
process control is best left up to microcontrollers, as they can stay 'focused' on the task.
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Test operation of the heater control by turning it on and watching for a rising
temperature.
Test operation of the fan control.
Turn off the heater.
Allow the incubator to cool back down to room temperature.
Turn off the fan.
Reset the plot.
Note that minimum and maximum temperatures were recorded in the text boxes.
Click the "Clear Min/Max" temperature button.
Turn on the heater and monitor the heating of the incubator until stable.
Turn off the heater and allow cooling to below 120 °F.
Energize the heater.
When temperature reaches 120 °F, click the "Clear Min/Max" button on
StampPlot.
Control the heater and fan for 2 minutes (1 grid division) while controlling
temperature as close to 120 °F as possible.
After 2 minutes disconnect on StampPlot.
maximum temperatures, how did you do?
Disconnect power to your Board of Education to ensure the heater is off.
Based on your minimum and
Multiple