Using Second Display as Customer Display

Hello

I have instaled Sambapos on the Maschine on this Link. In fact it is working well.
It has 2 Screens.

http://www.imachine-tech.com/p1-windows-desktop-pos-terminal_p34.html

Developper said: Our mainboard is EDP+LVDS, second screen connect com port name is com1

I cannnot communicate with this screen with following Commands
C:>
echo testing123>COM1
echo testing123>COM2
echo testing123>COM3
echo testing123>COM4
echo testing123>COM5
echo testing123>COM6
echo testing123>COM7
echo testing123>COM8

I would like to show on this second screen information for customers. Items and Price.

What i am doing wrong?

Thanks

https://kb.sambapos.com/en/2-4-13-a-how-to-create-basic-customer-screen-html/