question

if you are refering to the REC BMS's can connection then as far as I know this plugs directly into the canbus as a spur the canbus back bone normally has to be powered and there has to be a 120 ohm terminator resistor at end of the bus and a VE-BMS unit is not required.

or are you refering to the victron VE-BMS then the Rec bms is connected to the plugs on the bottom of the unit, if so it works only on the VE-BUS network (it must not be connected to the CAN BUS)

1. It signals the multi/quattro to stop inverting if it gets low cell voltage signal from the BMS being used

2 It tells the multi/quattro to stop charging if it gets high cell voltage signal from the BMS being used

on the bottom of the VE-BMS unit there are two plugs one male one female. these are just 3 looped circuits (ie closed circuit, there are 3 wires in the loop one blue one brown one black

As a example

Brown loop is closed the cells are ok and then if BMS opens the circuit as a cell voltage drops below set figure it signals the Multi/Quattro to stop inverting

BLUE loop is closed the cells are ok and then if the BMS opens the circuit as a cell voltage goes over the set figure it signals the multi/Quattro to stop Charging

Black is opened by the bms if the temp goes low or high it signals the multi/Quattro to stop inverting and charging

so this loop wire is TOTALLY controlled by the bms you are using and then the BMS cell units themselves report to the BMS you are using . normally all 3 loops are closed if any one of them open then the required trigger caused the VE BMS unit to send the signal to the multi./quattro to respond accordingly.

NOTE Brown and Blue colours maybe reversed as to what they do in the example above so test first.

hope the above makes sense.

I'm not sure that those 3x looped signals are steady ones, some manual refer to it "as communication".
Is there anyone who can confirm that?