In the Orion-Tr Isolated DC-DC Chargers, the remote on/off circuit is referenced to the primary battery (e.g. starter battery). The Orion-Tr Isolated DC-DC Charger Remote Cable is intended for applications where the remote on/off signal is referenced to the secondary battery (e.g. lithium battery with BMS).
More about Victron:
Victron Energy has a strong, unrivalled reputation for technical innovation, reliability, and build quality. Their products are widely considered to be a professional choice for independent electric power. Efficiently combining two or more distinct power sources is what they do best. Their products include sinewave inverters, sinewave inverters/chargers, battery chargers, DC/DC converters, transfer switches, battery monitors and more.