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According to NI, NTM commands can be sent to the Node. They are the follwing:

  • Start Remote Node
  • Stop Remote Node
  • Enter Pre-Operational
  • Reset Node
  • Reset Communication.

Start Remote Node enables all services. Stop Remote Node disable all services, except NMT service. Enter Pro-Operational only disable PDO service.

But what does Reset Node and Reset Communication in practice? I have heard that Reset Node reset ALL values of the device to the power on values, e.g default values. But I'm not sure about that.

I'm definitely not sure about Reset Communication. What communication? Do they mean services?

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Each node is supposed to have an internal state machine, which basically goes: coming out of reset into an initialization state -> pre-operational -> operational. How exactly these are implemented is vague and for each product to decide. Though you are not allowed to do PDO communication unless operational, and you are not allowed to switch to operational while there are errors present.

Reset could be implemented as in run the whole CANopen protocol stack initialization over again from the start. Or it could be implemented as a hard MCU reset. I'm not entirely sure what difference reset communication is supposed to do, I'd have to study the standard. But from what I remember it'ss about the same - probably running the initialization code once again but perhaps not doing a hard reset. Is means re-start everything and not just LSS.

I think that in both these cases you end up in initialization state and re-transmit a boot-up message upon transition to pre-operational.

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  • \$\begingroup\$ I tought that reset node means reload the whole OD from memory. Reset Communication means reload parts of OD from memory. In that case, reload the services. \$\endgroup\$
    – MrYui
    Oct 12 '21 at 9:30

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