typedef struct
{
unsigned short usCurrentMsg; // This is the current
UDP package number.
unsigned short usTotalMsg; // This is the total number
of UDP packages.
long lSeqNo;
long lMsgID;
} ParamMsgHdrDef;
lSeqNo: This is the “Value and attribute update" number. It is incremented for each UDP package. In a Server alive message this means the last used sequence from the server. In an Request retransmit message, this means the UDP package that should be re-transmitted.
lMsgID: This is the identification of the current message. The following values are defined.
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const long lPM_SERVER_ALIVE = 3; |
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const long lPM_REQUEST_RETRANSMIT = 4; |
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const long lPM_VALUE_ATTRIBUTE_UPDATE = 6; |
If the amount of data exceeds the limit of one UDP message, the data will be split into multiple UDP messages. The TotalMsg field contains the number of UDP messages for the current data. This is identified with any number larger than 1. The CurrentMsg field contains the current UDP package number out of the total number of packages.
The actual parameter notification data is organised as follows:
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Value and attribute update messages
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Parameter update structures |
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Attribute update structures |
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Request re-transmit message |