TCP Communication Handles with No Port Number


#1

Hey all,

 I want to use a LED marquee sign with an Opto-22 Snap-Pac-R1 controller that I have and I want to communicate using Ethernet if possible. The marquee sign is made by EZAutomation:

http://www.ezautomation.net/products/ezmarquee_models.php

I know I have to use a tcp communication handle but the documentation for the marquee sign does not specify what port number to use, it seems they do not need a port number?

Do I have to specify a port number when I use a communication handle or can I just specify the IP address? Has anyone run into this before and know of the “secret” port number that needs to be used? Any help would be greatly appreciated. Thanks!


#2

Hi Duffanator
All TCP communications rely on a port to transfer data. Some ports are defined by their protocol (http:80, https:443, ftp:21, telnet:23 etc…). To use the communication handle you must specify a port or else the handle will not know which port it needs to connect to. if a random port is selected like 88, that particular port may not be opened on the device.

I would suggest you contact technical support for the device to see which one is used. i am unaware of any “secret” port number, but if there is one I’d like to know!

If tech support will not help you, the another option is to use a program such as wireshark to ‘sniff’ the communications and retrieve the port number from there.

I hope this helps


#3

I did get a response from their tech support, the port number they use for ASCII communication is 49999. FYI in case anyone else is interested. Thanks for the response!