ICP DAS USA PISO-DNM100-D User Manual

PISO-DNM100 DeviceNet Master API functions User’s Manual (Ver: 1.0) 2008/02/25 222.3.3 Wire connectionIn order to minimize the reflection effects on the CAN bus line, the CANbus line has to be terminated at both ends by two terminal resistances as in thefollowing figure. According to the ISO 11898-2 spec, each terminal resistanceis 120Ω (or between 108Ω~132Ω). The length related resistance should have70 mΩ/m. Users should check the resistances of the CAN bus, before theyinstall a new CAN network.Figure 2.4 CAN bus network topologyMoreover, to minimize the voltage drop over long distances, the terminalresistance should be higher than the value defined in the ISO 11898-2. Thefollowing table can be used as a good reference.Bus Cable ParametersBus Length(meter)Length RelatedResistance(mΩ/m)Cross Section(Type)TerminalResistance(Ω)0~40 70 0.25(23AWG)~0.34mmP2P(22AWG)124 (0.1%)40~300 < 60 0.34(22AWG)~0.6mmP2P(20AWG)127 (0.1%)300~600 < 40 0.5~0.6mmP2(20AWG)150~300600~1K < 20 0.75~0.8mmP2P(18AWG)150~300Table 2.4 Relationship between cable characteristics and terminalresistance