It looks like you get the data by polling, which means you don't need threads or multiple processes. Simply poll the device at your preferred interface and plot a single point.
Here's an example with some simulated data to illustrate the general idea. It updates the screen every 100ms.
import Tkinter as tk
import random
class ServoDrive(object):
# simulate values
def getVelocity(self): return random.randint(0,50)
def getTorque(self): return random.randint(50,100)
class Example(tk.Frame):
def __init__(self, *args, **kwargs):
tk.Frame.__init__(self, *args, **kwargs)
self.servo = ServoDrive()
self.canvas = tk.Canvas(self, background="black")
self.canvas.pack(side="top", fill="both", expand=True)
# create lines for velocity and torque
self.velocity_line = self.canvas.create_line(0,0,0,0, fill="red")
self.torque_line = self.canvas.create_line(0,0,0,0, fill="blue")
# start the update process
self.update_plot()
def update_plot(self):
v = self.servo.getVelocity()
t = self.servo.getTorque()
self.add_point(self.velocity_line, v)
self.add_point(self.torque_line, t)
self.canvas.xview_moveto(1.0)
self.after(100, self.update_plot)
def add_point(self, line, y):
coords = self.canvas.coords(line)
x = coords[-2] + 1
coords.append(x)
coords.append(y)
coords = coords[-200:] # keep # of points to a manageable size
self.canvas.coords(line, *coords)
self.canvas.configure(scrollregion=self.canvas.bbox("all"))
if __name__ == "__main__":
root = tk.Tk()
Example(root).pack(side="top", fill="both", expand=True)
root.mainloop()
