PCT EET320 Utilities

Two Python utilities for EET320/EET321 at the Pennsylvania College of Technology.

This repository is designed for use in the electronics labs in the BWD building at Penn College.
It is not intended as a general-purpose device discovery tool.

To use, download PCT_EET320.py to the same folder where the lab Python code is stored.
At the top of the file with the other imports, include the following:

import PCT_EET320 as pct

This allows either function to be called with the prefix pct.

Functions

addr_assign()

This function imports PyVISA and automatically opens a connection to every piece of benchtop equipment it can find.
It is able to automatically identify and assign the USB addresses to allow easier transition between lab workstations.
If PyVISA is not installed, this function will ask the user to allow PyVISA to be installed, and then it will be imported.

addr_assign() is passed no values and returns nothing.
However, it creates global variables to be used by user-defined functions and methods.
These variables are used to communicate with the benchtop test equipment used in lab.
The variables are:

VARIABLE	PURPOSE
oscope	Oscilloscope
supply	DC Power Supply
fungen	Function / Arbitrary Waveform Generator
dmm	Benchtop Multimeter

To use one of these variables in a function, first use the `global` keyword and declare the variables you are going to use.
Then, use the variable to make the write or query.
The variables must be first declared as globals in a user-made function or method so a local variable with the same name is not instantiated.

Example:

import PCT_EET320 as pct
pct.addr_assign()

global supply  #declares that the global variable 'supply' is used
global dmm     #declares that the global variable 'dmm' is used

# Other code here

supply.write("CH1:VOLTage 5")             #Sets the DC power supply to 5V on channel 1
measurement = dmm.query("MEAS:VOLT:DC?")  #Measures the voltage with the multimeter and places the value in 'measurement'

This shows how the addr_assign() function could be used in a user-defined function.

eng_note(inputValue, numSigFigs)

This function converts a number into engineering notation representation.
This function is intended to format data for readability on the terminal. It will not be formatted correctly for use in a CSV file or Excel spreadsheet.

Inputs:

• inputValue - The numerical value to convert into engineering notation representation.
  • Can be type float, int or string
  • If string, it must only contain numeric characters and a decimal point
• numSigFigs - The number of significant figures the string will be formatted with.
  • If left blank, the string will contain the maximum number of available digits.

Returns:

• A string containing the formatted number and engineering notation prefix.
  • If inputValue is within the range of prefixes, the string will be numSigFigs + 3 characters wide and right-justified. If numSigFigs is not specified, then the string may be longer or shorter.
  • If inputValue is too large or too small for the range of prefixes, then the string will default to scientific notation. The string will contain the appropriate amount of significant figures, but the length of the string will be dependent on the size of the scientific engineering exponent.

Range of prefixes:

Symbol	Prefix	Power		Symbol	Prefix	Power
'Y'	yotta-	1024		'y'	yocto-	10-24
'Z'	zetta-	1021		'z'	zepto-	10-21
'E'	exa-	1018		'a'	atto-	10-18
'P'	peta-	1015		'f'	femto-	10-15
'T'	tera-	1012		'p'	pico-	10-12
'G'	giga-	109		'n'	nano-	10-9
'M'	mega-	106		'u'	micro-	10-6
'k'	kilo-	103		'm'	milli-	10-3

Example:

import PCT_EET320 as pct

num1 = pct.eng_note(3.1415926, 5)  # No prefix
print("num1 = " + num1)

num2 = pct.eng_note(27182818, 3)  # Prefix for positive exponent
print("num2 = " + num2)

num3 = pct.eng_note(0.0001618033988, 6)  # Prefix for negative exponent
print("num3 = " + num3)

num4 = pct.eng_note(-0.00060221415, 6)  # Negative number, same sig figs
print("num4 = " + num4)

num5 = pct.eng_note(1414213562373095048801688724209, 5)  # Out of prefix range
print("num5 = " + num5)

num6 = pct.eng_note(0.707106781187)  # No sig figs specified
print("num6 = " + num6)

Output:

num1 =  3.1416
num2 =  27.2M
num3 =  161.803u
num4 = -602.214u
num5 =  1.4142e+30 
num6 = 707.106781187m

This demonstrates how the output of eng_note() changes based on input parameters.