When powering the WatchMonCORE (version 4.5) with a supply above 30Vdc (i.e. 48V battery pack voltage), always connect to an isolated DC-DC (ideally 24Vdc) to ensure a robust, long-term, and reliable product.
Isolated DIN Rail Mount DC/DC Converter, Railway, 4:1, 15 W, 1 Output, 24 V, 0.6 A
Input Voltage DC Min 18V Input Voltage DC Max 75V
*This should be enough as the WatchMon only needs 2W.
Cell Monitor port (aka CMU) now with its own external fully isolated communication module named "IsoMon3" that can link to LongMon, BlockMon and LeafMon
CMU and Shunt serial ports have different sets of pins to avoid confusion
New onboard Relay (30vdc 5a relay) making it easier for DIY wiring
The communication bus is now fully isolated to prevent issues when connected to some equipment that is not properly grounded. The Isolation requirement is now stipulated by some inverters available in the market. The 120ohm terminating resistor is now mounted to the circuit board and can be removed if required (via cutting the resistor leg). This eliminates the need to combine the resistor with the cabling on the plug. More of the new features of the WatchMonCORE are in this article: WatchMonCORE - What is different?
You should also NOT add an extra 120ohm resistor as this is already built into the WatchMon, doing so will prevent the CANbus from working.