In or order to request spesific data from one node that uses J1939 protocol, is it necessary to claim address before requesting that data? Do we also need to request PGN before that process? Or can we directly request data without requesting PGN or claiming address? Thanks.
Address claiming indicate that you are owner of the perticular address AND there is no other node with same address.
If you know the network will not have any other node with your node address, you can directly request the data. However, you will not comply with J1939 standards.
Your device will not be generic and will be specific to your own network (where you are sure that no other node is using same address).
In short, You can do away address claiming but you should not!