The "INVALID PORT" error message on a payment terminal typically indicates that the terminal is not able to communicate with the system it is trying to connect to. This could be due to a variety of reasons such as driver issues on the port, POS issue, the terminal might be unplugged from POS or base, the base is not getting power or broken cables.
To tackle the issue of an invalid port, follow the below steps:
Check the below:
The terminal is sitting properly on the base to get power (Should make a "beep" sound when you pick it up)
The cables are not damaged
Everything is plugged in
Once that is checked, restart the terminal.
If restarting POS does not fix it, update the Linkly Drivers.
If the error is still occurring, try plugging in the USB cable to another port
If it is still not working, please contact Till Customer Support team by submitting a ticket.