Two ax3500 controllers on one PC

I want to use one PC to upload to 2 ax 3500 controllers. Can the software upload to two different controllers, a master and a slave? Would I need to make a separate cable connection to each 3500?

Easiest set up is to have a PC with two serial ports (example using a USB to RS232 dual port which is very inexpensive. Call them Port1 and Port2 then connect each controller to a port.
Any software command issued to Port1 will be routed to a controller, and to Port2 to the other.