Default port is 9100

example/example.dart

 import 'package:esc_pos_printer/esc_pos_printer.dart';
 
 main() {
-  Printer.connect('192.168.0.123', 9100).then((printer) {
+  Printer.connect('192.168.0.123').then((printer) {
     printer.println('hello world :)');
 
     printer.cut();

lib/src/printer.dart

@@ -26,8 +26,8 @@ class Printer {
   ///
   /// The argument [timeout] is used to specify the maximum allowed time to wait
   /// for a connection to be established.
-  static Future<Printer> connect(host, int port,
-      {sourceAddress, Duration timeout}) {
+  static Future<Printer> connect(host,
+      {int port = 9100, sourceAddress, Duration timeout}) {
     return Socket.connect(host, port,
             sourceAddress: sourceAddress, timeout: timeout)
         .then((socket) {