TCP Communication Handles with No Port Number

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:

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!

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

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!