Hi Cindy,
are you using the Raspberry image from PANS? If you runs default PANS image, it will try to configure the module to Bridge mode. If you want to take control over the DWM1001-DEV, then you need to stop DWM Proxy, DWM Daemon and then DWM Kernel:
sudo /etc/init.d/dwm1001 stop
sudo /etc/init.d/dwm1001-proxy stop
sudo rmmod dwm
Then you can do what is needed via the /dev/serial0. E.g.
minicom -D /dev/serial0 -b 115200
Cheers,
TDK