RTK correction from base to moving base

Hi,
I’m using a simpleRTK2B+heading modules to have an accurate heading, and I use also a fixed base sending RTK correction to simpleRTK2B+heading modules to get an accurate GPS position.
Is there a UBX message to know if the simpleRTK2B+heading modules are receiving RTK correction from the fixed base ?
Thanks for your help.