CanFaq

This is the Wiki Wiki CAN FAQ

• Why maintaining it this way?
  • Because if many experts are contributing, the FAQ should be more precise and growing faster.
• What is CAN?
  • try to answer it here or see http://www.can-cia.org/index.php?id=170
• Where is CAN used?
  • http://www.can-cia.org/applications/
• When was CAN invented?
  • http://www.can-cia.org/index.php?id=574
• Where do I get the standards from?
  • The only place is http://www.iso.ch , search for 11898-1
• How does CAN work?
  • http://www.can-cia.org/index.php?id=84
  • An older CiA presentation describing the physical layer, can be found at http://weble.upc.es/asig/ea/practica4/CANphy.pdf
  • Another CiA presentation describing the data link layer DLL http://weble.upc.es/asig/ea/practica4/CANdll.pdf
  • Different CAN implementions in silicon are described in http://weble.upc.es/asig/ea/practica4/CANimpl.pdf
  • CAN application fields http://weble.upc.es/asig/ea/practica4/CANappl.pdf
• What kind of physical layer is used?
  • http://www.can-cia.org/index.php?id=88
• Why is my CAN not working ? Here are some ProblemSolvingQuestions
• What are Error Active, Error Passive, and Bus off of CAN Bus?
  • read more: CanFaqErrors:
• What are commonly used bit rates?
  • read more: CanFaqBitrates
• Can a CAN Transceiver blow-up when connected to RS232?
  • read more: CanFaqBlowUpRS 232
• What is the difference between Basic CAN and Full CAN?
  • read at CanFaqBasicFullCAN
• What is TTCAN
  • Time Triggered CAN - to make CAN more predictable. All you need to know at a first glance can be found at the CiA TTCAN page http://www.can-cia.org/can/ttcan/ . There are also some PDF papers available.
• What connectors are used ? See CanConnectors
  • depends of the suggestions made in higher layer protocols. The most different kind of connectors and there pinning are described in the CiA paper CiA DR 303-1 V 1.1.1 part 1: CANopen Cabling and Connector Pin Assignment. Version 1.0 can be found at: http://www.datamicro.ru/can/standards/pdf/DR303-1.pdf
  • Some can also be found directly here: http://www.cd-systems.com/Can/can-cables.htm
  • Beware! Some manufacturers use proprietary pinning!
• WhatIsWrongWithRTR ? using remote transmission requests
• What is CanMessageFiltering ?
• How is the BusOff handled by the CAN controllers?
• What is the maximum CanCableLength ?
• What is GMLAN ? General Motors CAN protocol. See http://www.gmtcny.com/lan.htm

the above link does not work!

• Is the filter for CAN messages before or after the receiver/ACK hardware?
  • jk: ACK is always sent by all enabled nodes receiving a valid frame that are not the transmitter of the frame. Filtering only determines whether or not the received message gets stored in a mailbox, and for controllers with multiple filters, which mailbox. Filtering comes after the ACK is sent.
  • pk: You may also have to set the acceptance filter much wider and do the final filtering in the software, the ACK mechanism would still not be an indication that someone is actually interested in your message.
• What is Fault Tolerant CAN ?
  • See ISO 11898-4