Use the Blue Iris macros feature to display transaction data from Verifone Ruby & TOPAZ POS registers.
python -m pip install pyserial
python serial_capture.py
Only 2 pins need to be connected to the COM port (GND & RX). POS system needs to configured to output DVR data via serial on COM5 in the POS settings. Google verifone topaz backdoor codes to gain access to these configuration options.
Configure a macro to display the contents of the clipboard log file generated by the script. Go to your desired camera video options and choose overlay and enter the macro ID (ex. %1) to enable the macro.