How to create an if statement with serial data?

Question

How would I write the code so if I recieve 'hello' it runs a function?

import serial


ser = serial.Serial(port='/dev/tty.usbmodem11201',baudrate=9600)

while True:
    value= ser.readline()
    valueInString=str(value, 'UTF-8')
    print(valueInString)

    if ser.is_open == hello:
        print("Hi")

This is what I saw to do but it did not work. How would I get it to work? Thanks!

If you want to get help here, you need to do better than "it did not work." Tell us what happened, and what you expected to happen or wanted to happen. — Paul Cornelius
– Paul Cornelius, Commented Mar 9 at 4:02
If you want to execute a function when hello is returned, then just replace the print("Hi") line with the function call. And in the if condition, I think you meant "hello" in quotes. — Vansh Patel
– Vansh Patel, Commented Mar 9 at 4:08
You might want to try to find a different module to handle your serial port because the documentation for pyserial 3.5 is no longer applicable to Python 3.13.2 — jackal
– jackal, Commented Mar 9 at 9:16

SyntaxTerror · Accepted Answer · 2025-03-09 05:15:19Z

2

ser.is_open == hello is wrong. It checks if the serial port is open, not if the message is "hello".

if valueInString.strip() == "hello":

edited Mar 9 at 5:15

answered Mar 9 at 5:09

SyntaxTerror

601 silver badge6 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Tux-76 · Accepted Answer · 2025-03-09 04:17:13Z

1

You need to refine your "if" statement. It should be:

if ser.is_open == True:
    if valueInString == "hello":
        print("Hi")

ser.is_open is simply a Boolean value for whether the serial communication is open. You want to compare valueInString for "hello"

Also, consider adding .strip() to your valueInString definition to remove white space, like so:

valueInString=str(value, 'UTF-8').strip()

answered Mar 9 at 4:17

Tux-76

1341 silver badge7 bronze badges

Collectives™ on Stack Overflow

How to create an if statement with serial data?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related