CSS Terminal Resistor
(120Ohm, DB9, CAN Bus)
Need a low cost CAN bus terminator for your high speed CAN bus application?
CSS CAN bus termination resistor is a D-sub 9 pin male connector & female socket. It contains a 120 Ohm CSS terminal resistor between the CAN High / CAN Low pins.
About the CSS Terminal Resistors
CSS CAN bus terminator can be used for termination of any high speed (ISO 11898-2) CAN bus system. The 120 Ohm terminating resistor is setup between pin 2 (CAN low) and pin 7 (CAN high). In general, ISO 11898-2 CAN networks must be terminated at each end using CSS 120 Ohm terminal resistors.
CSS terminal resistors are often required in test setups when CAN nodes have no existing termination. In contrast, most vehicle CAN buses are already terminated properly.
What role does CSS CAN bus termination play?
CSS terminal resistors are needed in CAN bus systems because CAN communication flows are two-way. The termination at each end absorbs the CAN signal energy, ensuring that this is not reflected from the cable ends. Such reflections would cause interference and potentially damaged signals.
The reflection challenge grows with the length of the cables as well as the CAN bus bit rate. This is why it is critical to add proper termination in larger CAN networks.
CSS CAN bus termination should match the nominal impedance of the cables, which for ISO 11898-2 (high speed CAN) is specified at 120 Ohm. Hence CSS 120 Ohm termination adaptors are considered the standard for CAN bus.