Controllino serial communications issue

Greetings

To get to the core of my problem withought completly explaining my project: I have an issue to make a serial connection between the PC trough a excell VBA program i wrote and the controllino mini PLC. (connected on it's usb port)

The same VBA program is perfectly capable of establishing connection with an arduino Uno via the same port and accept commands for the control of a stepper motor. The same arduino program that works with the uno is uploaded on the controllino and works. (tested trough serial monitor)

My question is: whats different with the Controllino that i wouldn't be able to establish a serial connection in the same way i do it with the arduino? (the comm port was different but i changed the program for that difference)

My question is: whats different with the Controllino

The Controllino is not an official Arduino. If you want to ask questions about it here, you'd be smart to at least provide a link, so we know what you are talking about.

Can your VBA app connect to a Leonardo or Micro? Those require setting the DTREnable flag, while the UNO does not. Maybe the Controllino needs that flag set.