Timeline for Hot pluggable CAN collections of devices
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 14 at 5:02 | comment | added | Astrinus | Well, in theory it's "discouraged" but if you go slow enough and keep the stubs short (< 2 m), it usually works fine (stubs are explicitly allowed so given your constraints it's ok). The "right thing" would be going back and forth on each branch (U-shape), but obviously this makes hot plugging of whole sections harder. CAN gateways/hubs are used when stubs are longer or run on different speeds. | |
| Jun 13 at 15:34 | comment | added | iBax | I am definitely considering CAN FD, just was more concerned about the branches off the main bus as I couldn't find anywhere that was expressly "allowed" with CAN. | |
| Jun 13 at 8:39 | comment | added | Astrinus | Also look into CAN FD SIC transceivers. They improve ringing in data phase (and using CAN FD means you can go up to 64 bytes frames, so you may reduce overhead, even if you don't use an higher data rate). | |
| Jun 13 at 8:30 | comment | added | Astrinus | It seems fine for your use case. Look into CAN in Automation recommendations about bus / stub length: old.can-cia.org/ru/can-knowledge/canopen/canopen-lower-layers - 125 kbit/s seems to be attainable with your configuration (mind that you might have capacitance issues with so many devices that may distort the signal too much, so make sure to build the maximum network and test with an oscilloscope at several nodes). Also mind that with 500 nodes and 1 ms/message (8 bytes, 11-bit IDs ~> 110-120 bits) every node gets to transmit more or less 1 message per second (at 50%-60% bus load). | |
| Jun 13 at 1:52 | answer | added | Voltage Spike♦ | timeline score: 0 | |
| Jun 13 at 1:44 | comment | added | iBax | Thanks for the speedy reply! The CAN bus in each collection could be up to 1 meter and the 'always there' CAN Bus would be ~2 meters. I don't have a required speed and could likely get by with something rather slow. BTW, you mention it can be fine, but is there a better way that I should be doing it (e.g. 2-channel, use a hub, add termination resistors, etc.)? | |
| Jun 13 at 1:28 | comment | added | user1937198 | What speed are you running at, and long are the runs into your subcollections? For sufficiently 'low' speeds and 'short' stubs it can be fine. | |
| S Jun 13 at 1:12 | review | First questions | |||
| Jun 13 at 10:28 | |||||
| S Jun 13 at 1:12 | history | asked | iBax | CC BY-SA 4.0 |