GUI program for turning on/off a projector via RS232

Question

I'm pretty new with the Raspberry enviroment, but I managed to write a code in Python 2, watching a lot of videos and post on this website. What I'm trying to do is a simple GUI with an ON/OFF switch for turning ON/OFF a projector.

I managed to create a window with a button that says on/off and an exit button as well. For turning on or off the projector, I use another codes, I'll put them below. I'm using a USB to Serial HUB RS232 converter,it has 4 RS232 Ports.

The entire thing works like this so far, When I start it and press the button, it sends the codes for turn the projector off, but it only works once, when I press it again it doesn't do anything, like it doesn't load the code for on/off anymore.

Ultimately, I want to do this for 4 projectors, so my thinking is to replicate the codes for on/off and changing the port name:'\dev\ttyUSB0 for USB1, USB2 and so on.

Any idea on how to help me solve this is gratefully accepted!

The commands for turning on/off the projector are these:

Baud rate: 9600
Data Length: 8 bits
Parity bit: None
Stop bit: 1 bit
Communication mode Full duplex

Turning On the projector: 02h 00h 00h 00h 00h 02h
Turning Off the projector: 02h 01h 00h 00h 00h 03h

This is my code so far

from Tkinter import *
import tkFont
import RPi.GPIO as GPIO


GPIO.setmode(GPIO.BOARD)
GPIO.setup(40, GPIO.OUT)
GPIO.output(40, GPIO.LOW)

win = Tk()

myFont = tkFont.Font(family = 'Helvetica', size = 36, weight = 'bold')



def ledON():
print("LED button pressed")
if GPIO.input(40) :
             ledButton["text"] = "ON"
             import SerialOFF
else :
            ledButton["text"] = "OFF"
            import SerialON

def exitProgram():
print("Exit")
    GPIO.cleanup()
win.quit()


win.title("NEC Control")

win.geometry('800x480')

exitButton  = Button(win, text = "Exit", font = myFont, command =     exitProgram, height =2 , width = 6)
exitButton.pack(side = BOTTOM)

ledButton = Button(win, text = "Iniciate", font = myFont, command = ledON,    height = 2, width =8 )
ledButton.pack()

mainloop()

And these are the codes for switching on/off the projector, for the Off part is the same, I just changed the command line and the ON parts

ON
import time
import serial

ser = serial.Serial(
 port='/dev/ttyUSB0',
 baudrate=9600,
 parity=serial.PARITY_NONE,
 stopbits=serial.STOPBITS_ONE,
 bytesize=serial.EIGHTBITS
 )

 ser.close()
 ser.open()
 ser.isOpen()


 ON=bytearray([0x02,0x00,0x00,0x00,0x00,0x02])



 ser.write(ON)
 print(ser.name)
 ser.close()

Answer 1

It's irritating when you get 99% of the way there. I've done this myself (not in python - in LabVIEW!) I trust your projector doesn't have a network port? This would make your life a lot easier if you're controlling multiple projectors.

You have your commands for on and off correct, BUT you're not listening for the response from the projector. I don't think you can issue a subsequent command without first receiving the projector's response.

success: 22h 00h (ID1) (ID2) 00h (CKS)
failure: A2h 00h (ID1) (ID2) 02h (ERR1) (ERR2) (CKS)

Enjoy!!

Answer 2

Python will not actually import a module twice. If you really want to import it again, you should use reload. Altough I would rather make a on_off function, with the command as parameter.

def on_off(cmd):
    ser = serial.Serial(
     port='/dev/ttyUSB0',
     baudrate=9600,
     parity=serial.PARITY_NONE,
     stopbits=serial.STOPBITS_ONE,
     bytesize=serial.EIGHTBITS
    )

    ser.close()
    ser.open()

    cmd=bytearray(cmd)

    ser.write(cmd)
    print(ser.name)
    ser.close()

Then you call them as so:

on_of([0x02,0x00,0x00,0x00,0x00,0x02])