I don't think there is an easy way to do this with PYVCP but it isn't too hard with Glade.
If you use GladeVCP you can use the python interface to directly read the status of LInuxcnc
linuxcnc.org/docs/2.6/html/common/python...ding_linuxcnc_status
the stat you'd use would be g5x_index
But you would probably need to write a little bit of python code to use it.
This is how the newer Glade based GUIs like Gmoccapy do it.
I've muddled my way through doing some things like this, but please don't ask me to explain exactly how to it.
There are some good GladeVCP tutorials for Linuxcnc out there.