The following table describes the query messages, that is the request-response pairs, used for data collection using the Ethernet connection.
|Response keys that are always sent are preceded by an asterisk (*).|
|Specification||Description||Request ID||Request data||Response key|
|NULL message||Included in query messages for debugging purposes as it can be used to check whether the server is listening. The message gives a high-level 'ping' functionality.||0x00000000||(none)||
|Protocol version||Responded to with a value representing the server (refractometer) protocol version.||0x00000001||(none)||*Version: integer, the server protocol version (currently 3)|
|Refractometer information||Gives the basic information of the refractometer.||0x00000003||0x00000000: always zero||
Gives the measured and calculated measurement values from the refractometer.
|0x00000004||0x00000000: always zero||