Industrial Control (Students guide, 1999, v1.1 )

DEBUG "!USRS Time:", HEX2 hours,":",HEX2 minutes,":",HEX2 seconds

DEBUG " Sample Due:",HEX2 LHours,":",HEX2 LMinutes,":",HEX2 LSeconds

DEBUG " # ",DEC MemAddr-4, " Temp now = ", DEC Temp,CR

DEBUG DEC Temp,CR

Return

SetTime:

'****** Initialize the real time clock to start time RTemp = $10 : RTCCmd = CtrlReg : GOSUB WriteRTC

'Clear Write Protect bit in control register

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HIGH RTCReset

SHIFTOUT RTC_IO, RTC_CLK, LSBFIRST, [%0\1,RTCCmd\5,%10\2,RTemp]

LOW RTCReset

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Return

We'll discuss operation and major blocks in our code. At the top of the code is the initialization information:

'******************************************************

This data defines the time to set the RTC, how long the interval between logging should be, and how many samples should be logged. Stop_Reset is defines whether to stop logging (1) or reset (0) and start over destroying the old data when the maximum samples are collected.

The pushbutton has several purposes:

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1.On-Power up or Reset of the BS2, a message will appear informing you to hold down the pushbutton to initialize the clock and logging (the LED will light for this also). If the button is held down, the value of time in the initialization section will be used to set the RTC and logging will be reset to the start. Recovery data will be written to EEPROM for the next reset.

2.During logging, if the pushbutton is pressed, the data will be ‘dumped’ or downloaded. We will be using StampPlot Lite to capture and plot the data as it is dumped. The data is NOT destroyed and the logger will continue to log new data.

3.At the end of a data dump, if the pushbutton is held down, the data logger will reset the log to the start destroying old data and resetting the start time of logging.

If the BASIC Stamp 2 is reset and the button is NOT held down, the program will read recovery data of current memory location and start time from the EEPROM. The RTC time will NOT be reset. It should be maintaining proper time through the reset UNLESS power was lost. Figure 7.7 is the flowchart of the initialization of the program.

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Figure 7.7: Logging Initialization Routine

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Figure 7.8: Control and Saving Routines

Time Control routine (Figure 7.8) is used to determine if it is time to save new data to memory. This is contingent on the memory location for samples being less than the number of samples specified.

TimeControl: ' Check if time for reading IF (Time = LTime) AND (MemAddr-4 < Samples) THEN SaveData

RETURN

The Save Data routine is called from Time Control when it is time to write a new sample to memory. The current DataIn (value read from the ADC) is stored in the current memory address, and the memory address is incremented for the next cycle. The next interval time is calculated (and later BCD adjusted). If the

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maximum number of samples is reached, depending on the Stop_Reset value, data logging will either ceased (see Time Control) or logging will start over.

Note that the raw DataIn value from the ADC is stored and not the temperature-calculated value. This allows the data to be stored in one byte instead of two as a word. The stored value will be converted into temperature when it is ‘dumped’ to the PC.

Figure 7.9 illustrates the flow of the DumpData routine. When the pushbutton is pressed, Dump Data configures StampPlot for plotting, and creates a loop reading through the logged values, converting them to temperatures, and sending the values for plotting and the message window. Note that the log time is set to the start time, and the timing interval is added to the log time each loop iteration to determine the original time the data was logged.

Once the loop is complete, the log time is set back to the current time and the user is requested to hold down the pushbutton to reset the logging to start (the LED will light for indication also).

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Figure 7.9: Data Dump Routine Flowchart

Once DumpData is complete, the control time will be updated to the time of the next sample, and logging will continue from the point it left off, allowing downloading without affecting the stored data. Figure 7.10a is a screenshot of our collected data dumped to StampPlot Lite.

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Figure 7.10a: Sample Data Dump of Logged Data

The format of the message data is suitable for importing into a spreadsheet for graphing, as seen in Figure 7.10b. A portion of the saved message file is as follows:

Point,Time,Temperature

0,22:51,787

1,22:56,787

2,23:01,787

3,23:06,787

4,23:11,783

5,23:16,783

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Figure 7.10b: Imported Message Data to Excel

We set the incubator outside of a window and recorded outdoor temperatures.. Outdoor temperature can be tricky due to effects of wind cooling, sunlight heating, and thermal layers in the canister trapping heat. We had quite a few spikes in readings. Can you do better?

Our plot shows temperatures from 22:51 to 22:51 the next night. Note the rise and falls in temperature during the day. The expected high for the day was 88F, and we came pretty close!

Of course, we are not restricted s temperature range 70F-120F. Refer back to Experiment #4. Software range values are determined by the span and offset voltage settings to the ADC0831.

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