20bit Code with x at the end - Mandoyn RC-710

[Woyton]

Hello,

I have a problem that I can not get any further. I have radio sockets of Mandolyn RC-710 - I could read the remote control with the Arduino. Sent a 6 digit decimal code and a 20 bit binary code. With the Arduino, I could control the sockets when an "x" ​​is sent along with the 20-bit code. The Mandolyn sockets definitely need this "x", otherwise they will not respond.
In the Arduino Scetch it looks like this:

mySwitch.send ("10110000000000001001x")

When I enter the decimal code with codesend on the Raspberry I get the correct binary code, but how do I attach the x? I made several attempts in the codesend.cpp, but to no avail and unfortunately I do not know how to continue. Does anyone have a solution or an indication where I'm stuck?

Thanks and best wishes
David