How to run a routine continuously until input is entered in command line? - Python

Question

Currently, I have a program that is designed to continuously send coordinates (encoded as ASCII) to a motor via socket communication, such that the motor moves with a sinusoidal motion. I would like for these coordinates to be continuously sent to the motor until the user enters end into the command line.

I have this currently:

import socket
import numpy as np
import math

pi = math.pi

s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #TCP Server Connection
s1.connect(("192.168.177.200", 4001))

gearpositionlim = 10000

# sample sine 
step = 2*pi / 2000
time_range = np.arange(0,2*pi + step,step)
x_motorrange = gearpositionlim*np.sin(time_range)
x_motorrange = ['la'+str(int(i)) for i in x_motorrange]

def motormove():
    for i in np.arange(0,len(x_motorrange)):
        s1.send(str(str(x_motorrange[i])+"\n").encode("ASCII"))
        message = s1.recv(1024).decode()

#-------------------------------------------
while True:
    motormove()
    name = input("Code Running: Type 'end' to end program: ")
    if name == 'end':
        break
    else:
        print("ERROR: Home position not returned to")
        exit()
#send the motor back to home position
s1.send("la0\n".encode("ASCII"))
s1.send("m\n".encode("ASCII"))
s1.send("np\n".encode("ASCII"))
s1.send("DI\n".encode("ASCII"))

However, the code currently only sends the coordinates x_motorrange once, then gives the input prompt to type end . Whereas, I would like for this prompt to always be present in the command line and for the routine motormove() to only stop when the prompt end is given. How can this be done?

Answer 1

insteade of writting exit you can use KeyboardInterrupt . so when you prees ctrl + c it will stop:

try:
    while True:
        do_something()
except KeyboardInterrupt:
    pass

Answer 2

There are many ways to solve this problem:

for example, move a of code to another thread or process

import threading
import socket
import time

import numpy as np
import math


class MotoMover(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        pi = math.pi
        self.id = 0
        self.s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  # TCP Server Connection
        self.s1.connect(("192.168.177.200", 4001))

        gearpositionlim = 10000

        # sample sine
        step = 2 * pi / 2000
        time_range = np.arange(0, 2 * pi + step, step)
        self.x_motorrange = gearpositionlim * np.sin(time_range)
        self.x_motorrange = ['la' + str(int(i)) for i in self.x_motorrange]
        self.connected = False
        self.stopped = False

    def try_to_connect(self):
        try:
            self.s1.settimeout(1000)
            self.s1.connect(("192.168.177.200", 4001), timeout=1000)
            self.connected = True
        except:
            self.connected = False

    def motormove(self):
        for i in np.arange(0, len(self.x_motorrange)):
            self.s1.send(str(str(self.x_motorrange[i]) + "\n").encode("ASCII"))
            message = self.s1.recv(1024).decode()

    def run(self): ## main cycle of the thread
        while not self.stopped:
            if not self.connected:
                #            print('connecting to server...')
                self.try_to_connect()
            else:
                self.id += 1
                self.motormove()
            time.sleep(1) #pause = 1 sec. you can reduce it to a few ms (0.01, for example), but I do not recommend removing it completely

    def stop(self):
        self.stopped = True


def main():
    moto = MotoMover()
    moto.start()

    while True:
        name = input("Code Running: Type 'end' to end program: ")
        if name.startswith('end'):
            print("end of the program")
            moto.stop()
            moto.join()
            exit(0)
        else:
            print('!', name)
            if len(name) >= 3:
                name = ''


main()