Object Dictionary does not get updated

[Phillip0407]

I have a real CAN-network with one device connected. This device tries to interact with another node that I want to simulate by a LocalNode object, which workds fine. I created an object dictionary with one ODVariable with the particular index and subindex on which the real device tries to perform an SDO Download (e.g. 0x1F51, 0x01) and assigned it to the LocalNode object.
The SDO Download completes successfully what I can observe via candump. However, when I try to access the value via the object dictionary from the local node, I can't see the updated value but the default one from the initialization. The only way I can access the updated value is via "node.sdo[0x1F51].raw", which is an SdoVariable and not the original ODVariable. At this point, I can not provide any subindex and when a second ODVariable got assigned before with the same index but different subindex, I only can check the updated value from the most recently added Variable.

I don't know if I understand wrong the concept of the different variable classes, but my guess was that the object dictionary of the LocalNode gets updated when another Node performs SDO Downloads.

If not, how can I access an Variable with index and subindex?

[acolomb]

You're right in your expectation about the OD getting updated. That's what a LocalNode should be doing through its SdoServer member.

Now I think you might be looking at the wrong thing and therefore coming to wrong conclusions. The ODVariable holds all the metadata about the object, and especially the actual value for a local SDO node. The SdoVariable is pretty much only an adapter to make SDO reading and writing easier. It points back to its associated ODVariable.

Now accessing local data through SDO is not wrong, as you might have thought. It basically just accesses the current cached data in the OD. There is no network overhead involved when calling this for a LocalNode. But of course you can also just look up the ODVariable object and use that directly the data should be identical.

If not, how can I access an Variable with index and subindex?

There is a get_variable() method on both the object dictionary and the SDO server class. That's how you easily find the right variable. But beware of the second argument's default value: if not specified, it will give you subindex 0 of any record or array.