Send GSD Command in JSON to Zebra Printer

Question

Trying to send commands (not labels) to Zebra printers using Python.

On page 574 of the documentation it shows:

Here's my code:

mysocket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)          
host= "192.168.100.245" # verified IP address of Zebra printer
port = 9100
mysocket.connect((host, port)) 
name_string= '''"sgd.name":null'''
my_string= f'''{{}}{{{name_string}}}'''
x = json.dumps(obj=my_string)
mysocket.sendall(bytes(x,encoding="utf-8"))
data= mysocket.recv(1024)
print(data.decode('utf-8'))

The printer responds to pings and other non-JSON Zebra commands sent to it (i.e. mysocket.send(b"~hs")). However, with the code above I wait for a long time and no response returns from the printer.

Tried multiple variations of the JSON formatting, what should I try next?

Per @bruan comment I tried the following variations but did not work:

my_string= '''"sgd.name":null"'''

my_string= '''{}{"sgd.name":null}'''

It looks like you create the JSON/command manually, then dump it into JSON one more time. What you send now is '"{}{\\"sgd.name\\":null}"'. I think you should send my_string as command. That said, better create JSON used in the command properly — buran
– buran, Commented Feb 29, 2024 at 17:11
@buran tried two variations based on your feedback, no success. — Python_Learner
– Python_Learner, Commented Feb 29, 2024 at 17:25
but did you remove the x = json.dumps(obj=my_string) line? Second one looks right — buran
– buran, Commented Feb 29, 2024 at 17:28

buran · Accepted Answer · 2024-03-06 06:45:32Z

1

You create the JSON/command manually, then dump it into JSON one more time. What you send now is '"{}{\\"sgd.name\\":null}"', i.e. the string "{}{\\"sgd.name\\":null}" Also, as I said in the comments, better don't create JSON manually. Use json module and it will be easier to expand the query dict and get multiple values at once if needed.

import json

# some lines skipped for brevity
query = {'sgd.name': None}
command = f'{{}}{json.dumps(query)}' # {}{"sgd.name": null}
mysocket.sendall(bytes(command, encoding="utf-8"))

edited Mar 6, 2024 at 6:45

answered Feb 29, 2024 at 19:10

buran

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