For a Low Speed CAN, termination resistors are required at the low speed transceiver (not at the cable). The termination requires one resistor : RTH for CAN_H, and RTL for CAN_L. If the Low Speed CAN card is set to be internally-powered, it still requires an external volatge (8-27 Volts DC) connected to the "V+" pin. This voltage is supplied to the "Vbat" pin on the card. The transceiver itself is powered by the PCI bus.
Thus, the cable requires 4 lines, CAN_H, CAN_L, V+, and V-. This same cable can be used for externally powered applications. When the switch is in the "external power" mode, the low speed CAN transceiver and the Vbat pin are powered by the external power. So in both externally and internally powered applications you always need to have external power conn
ected to the "V+" pin.
