Example Python script to implement the PID controller (plotting)

# pymoku example: PID Controller Plotting Example
#
# This script demonstrates how to configure both PID Controllers
# in the PID Controller instrument. Configuration on the Channel 1
# PID is done by specifying frequency response characteristics,
# while Channel 2 specifies the gain characteristics.
#
# The output response of each PID Controller channel is plotted
# in real-time.
#
# (c) 2019 Liquid Instruments Pty. Ltd.
#
from pymoku import Moku
from pymoku.instruments import PIDController

import matplotlib.pyplot as plt
from matplotlib.ticker import FuncFormatter


def from_dB(dB):
 # Helper function that converts from dB to linear scale
 return 10 ** (dB / 20.0)


# Connect to your Moku by its device name
# Alternatively, use Moku.get_by_serial('#####') or Moku('192.168.###.###')
m = Moku.get_by_name('Moku')

try:
 i = m.deploy_or_connect(PIDController)

 # Configure the Channel 1 PID Controller using frequency response
 # characteristics
 # P = -10dB
 # I Crossover = 100Hz
 # D Crossover = 10kHz
 # I Saturation = 10dB
 # D Saturation = 10dB
 # Double-I = OFF
 # Note that gains must be converted from dB first
 i.set_by_frequency(1, kp=from_dB(-10), i_xover=1e2, ii_xover=None,
 d_xover=1e4, si=from_dB(10), sd=from_dB(10))

 # Configure the Channel 2 PID Controller using gain characteristics
 # Overall Gain = 6dB
 # I Gain = 20dB
 # I Saturation = 40dB
 # Note that gains must be converted from dB first
 i.set_by_gain(2, g=from_dB(6.0), ki=from_dB(20), si=from_dB(25))

 # Set which signals to view on each monitor channel, and the timebase on
 # which to view them.
 i.set_monitor('a', 'out1')
 i.set_monitor('b', 'out2')

 # +- 1msec
 i.set_timebase(-1e-3, 1e-3)
 i.set_trigger('a', 'rising', 0)

 i.enable_output(1, True)
 i.enable_output(2, True)

 # Get initial data frame to set up plotting parameters. This can be done
 # once if we know that the axes aren't going to change (otherwise we'd do
 # this in the loop)
 data = i.get_realtime_data()

 # Set up the plotting parameters
 plt.ion()
 plt.show()
 plt.grid(b=True)
 plt.ylim([-1, 1])
 plt.xlim([data.time[0], data.time[-1]])

 line1, = plt.plot([])
 line2, = plt.plot([])

 # Configure labels for axes
 ax = plt.gca()
 ax.xaxis.set_major_formatter(FuncFormatter(data.get_xaxis_fmt))
 ax.yaxis.set_major_formatter(FuncFormatter(data.get_yaxis_fmt))
 ax.fmt_xdata = data.get_xcoord_fmt
 ax.fmt_ydata = data.get_ycoord_fmt

 # This loops continuously updates the plot with new data
 while True:
 # Get new data
 data = i.get_realtime_data()

 # Update the plot
 line1.set_ydata(data.ch1)
 line2.set_ydata(data.ch2)
 line1.set_xdata(data.time)
 line2.set_xdata(data.time)
 plt.pause(0.001)

finally:
 m.close()