Can Bus Cable Impedance

If you are designing both nodes then the 120 ohms resistors are indeed necessary and it s ok that you included them on your board.

Can bus cable impedance.

Bus length cable 1 terminating impedance maximum bit resistivity per rate meter cross section of line. However when dormant a low impedance bus such as can draws more current and power than other voltage based signaling busses. Therefore you should use 120 ω resistors for termination. 100 ohms would match the cat5 cable but the can transceivers would be seeing a lower impedance.

I see the can spec has a definition for rj45 connectors but the cable impedance is the issue. The termination resistors on a cable should match the nominal impedance of the cable. The distances from one end of the bus to the other will be fairly short 3 to 10 meters or so. The shielding reduces the harmful effect of emi or rfi interference.

Can l is pin 2 and can h is pin 7 on the standard 9 pin d sub connector. The termination resistors on a cable should match the nominal impedance of the cable. Iso 11898 requires a cable with a nominal impedance of 120 ω. On can bus systems balanced line operation where current in one signal line is exactly balanced by current in the opposite direction in the other signal provides an independent stable 0 v reference for the receivers.

The can bus cables are designed with materials that meet or exceed txl requirements and the impedance return loss and attenuation requirements of the network system. This is because communication flows both ways on the can bus. Iso 11898 requires a cable with a nominal impedance of 120 î. Can bus data cables delivering signal supplying power for transportation applications prestolite wire brand can bus data cables are designed to the sae j1939 specification utilizing proprietary materials specifically designed for exceptional electrical performance.

We also stock sab wire and cable products. Normally can bus has an impedance of 60 ohms therefore the two 120 ohms resistors at each end. This is because communication flows both ways on the can bus. Can l is pin 2 and can h is pin 7 on the standard 9 pin d sub connector.

Allied wire cable inc. Ul approved can bus cable is part of allied wire cable s extensive stock of electrical wire and cable. Is a distributor and manufacturer of custom cables coaxial cable flexible cables and a complete line of electrical connectors and heat shrink tubing. However be careful in this matter.

I could terminate with 100 ohms 110 ohms or 120 ohms. Therefore you should use 120 î resistors for termination.