I am experiencing an issue with the TC56, that it turns off the scanner if you turn off the screen. Im experiencing the same issue with the barcodeScanner sample app you can download on github. I have modified the samples OnPause, so it doesn't unregister the scanner. This should make the scanner work even when the screen is turned off or in the background.
 
 
1. Put the app into lockscreen / sleep mode.
2. start scanning with the hardware scan buttons.
 
after a few presses it stops scanning and its only the aim/seeker which is enabled.
The scanner beam should be visible too and working.