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I am studying the implementation of "Read Device Identification" function (0x2B / 0x0E). Response data frame for this function contains a field named "Number of Objects", but I do not seem to understand what it means. The Modbus Application Protocol document is not of much help to me in this particular case.
AFAIK, the Number of Objects could have one of these meanings:
1) Number of objects in the list transmitted within a single Modbus response. If multiple transactions are required to retrieve all objects using given access type, this field might have a different value in each transaction.
2) Total number of objects that can be retrieved from a Modbus server device using given access type. If multiple transactions are required to retrieve all objects, this field will retain the same value in all those transactions.
Can you please tell me which of the options above describe the meaning of "Number of Objects" field the best?
Thank you in advance
Ivo
AFAIK, the Number of Objects could have one of these meanings:
1) Number of objects in the list transmitted within a single Modbus response. If multiple transactions are required to retrieve all objects using given access type, this field might have a different value in each transaction.
2) Total number of objects that can be retrieved from a Modbus server device using given access type. If multiple transactions are required to retrieve all objects, this field will retain the same value in all those transactions.
Can you please tell me which of the options above describe the meaning of "Number of Objects" field the best?
Thank you in advance
Ivo