Use stable udev symlink for Datamax device instead of /dev/usb/lp0

app.rb

@@ -13,7 +13,7 @@ if !File.exist?('config.json') || !File.readable?('config.json')
   raise RuntimeException, 'Could not read config.json'
 end
 
-PRINTER_DEVICE = '/dev/usb/lp0'
+PRINTER_DEVICE = '/dev/usb/lp_datamax' # stable udev symlink, see /etc/udev/rules.d/99-datamax.rules
 PRINTER_DPI = 203 # DatamaxONeil E4204B Mark III native head resolution
 PRINTER_DARKNESS = 8 # lower than factory default to stop thermal dot-gain from fusing barcode bars
 TEST_LABEL_PDF = File.join(File.dirname(__FILE__), 'test-label.pdf')