Thermal Printer in Python

Sensors Imaging
1

I cannot print using Python.

I use the following code, copied from arduino example

import serial

ser = serial.Serial('/dev/serial0',
                    baudrate=19200,
                    parity=serial.PARITY_NONE,
                    stopbits=serial.STOPBITS_ONE,
                    bytesize=serial.EIGHTBITS,
                    timeout=1)


# Modify the print speed and heat
ser.write(27)
ser.write(55)
ser.write(7)  # Default 64 dots = 8 *('7' + 1)
ser.write(255)  # default 80 or 800us
ser.write(255)  # default 2 or 20us

# Modify the print density and timeout
ser.write(18)
ser.write(35)
ser.write(255)

# print
ser.write(b'Hello World\n')
ser.write(10)

ser.close()

I can print from bash (echo “Hello” > /dev/serial0).

Also the combination 18 35 does not exists in the manual, what does it do ?

2

Also the combination 18 35 does not exists in the manual, what does it do ?

Unfortunately I’m not sure either, it may be something left over from an older version of the thermal printer that never got removed from the example code.

As for your code, I can’t debug that, but the following sequence of bytes will setup the printer and print a hello world message. These are in HEX, you will need to convert them to decimal for your code unless you can alter the code to make the conversion for you.

Setup:

1B 37 07 FF FF 12 23 FF

Hello World!
12345678901234567890123456789012

48 65 6C 6C 6F 20 57 6F 72 6C 64 21 0D 0A 31 32 33 34 35 36 37 38 39 30 31 32 33 34 35 36 37 38 39 30 31 32 33 34 35 36 37 38 39 30 31 32 0D 0A 0A 0A
3

Thanks for the immediate response.

the hex values you 've sent me are the the same values I used in decimal.

Still it doesnt print. It only prints the very first line of the text (view image below)

https://drive.google.com/file/d/1ExHmDv … sp=sharing

4

If I try to print more than 4 characters (not numbers) the printer just prints the very first line

https://drive.google.com/file/d/1G-hAZp … sp=sharing

echo 1 > /dev/serial0

echo 10 > /dev/serial0

echo 100 > /dev/serial0

echo 1000 > /dev/serial0

echo 10000 > /dev/serial0

echo a > /dev/serial0

echo ab > /dev/serial0

echo abc > /dev/serial0

echo abcd > /dev/serial0

echo abcde > /dev/serial0

echo abcdef > /dev/serial0

echo abcdefg > /dev/serial0

5

Anyway, I will go with Arduino. It works flawlessly on it.

6

Not sure what might be causing the issue in Python but I’m glad it works OK for you in Arduino. :slight_smile: