You can add additional COM ports to WebHMI using USB-COM converters. Popular chips of such manufacturers are supported:
Attention: the operation modes such an extra port will support depends on specific manufacturer's implementatoin and drivers provided. In some cases, devices have been discovered being unable to work on certain speed, process parity bit etc.
After installing such a converter in the system, when configuring connections, it will be possible to select an additional serial port:
A special case of such a connection can be a direct connection of a PLC or other device to the USB port of WebHMI (usually a micro USB cable) directly. Onboard the PLC, in most cases, one of the above-mentioned USB-COM chips is installed.