It is customary to connect a 120Ω resistor between RS485 interface AB and CAN interface H and L. I only have 100Ω in stock. Can it be replaced?

oyhprince

It is customary to connect a 120Ω resistor between RS485 interface AB and CAN interface H and L. I only have 100Ω in stock. Can it be replaced? [Copy link]

It is customary to connect a 120Ω resistor between the RS485 interface AB and the CAN interface H and L. The warehouse only has 100Ω. Can 100Ω be used instead of 120Ω?

chunyang

That's called "parallel connection". You can use 100 ohms as a temporary replacement, but it is not recommended to use it for a long time or in large quantities.

chunyang

This resistor is called "terminal matching resistor", or "terminal resistor" for short. It is used to eliminate the adverse effects of signal reflection on signal quality, and its value should match the line impedance. Conventional twisted pair cables are valued at 120 ohms, and regular cable manufacturers produce them according to standards. If wires with other impedances are used, it is necessary to select a terminal resistor that matches the characteristic impedance of the wire. If the terminal resistor value is improperly selected and causes mismatch, signal reflection will have an adverse effect on signal quality, which will be more obvious at long distances, high speeds, and high interference, but will have little effect at short distances, low speeds, and a clean electromagnetic environment.