Records¶

All data lines are called records, and each record contains the following four fields:

The field are defined as follows:

cc

The byte count. A two digit hex value (1 byte), counting the actual data bytes in the record. The byte count is separated from the next field by a space.

aaaa

The address field. A four hex digit (2 byte) number representing the first address to be used by this record.

:

The address field and the data field are separated by a colon.

dd

The actual data of this record. There can be 1 to 255 data bytes per record (see cc) All bytes in the record are separated from each other (and the checksum) by a space.

ssss

Data Checksum, adding all bytes of the data line together, forming a 16 bit checksum. Covers only all the data bytes of this record.

Please note that there is no End Of File record defined.

Byte Count¶

The byte count cc counts the actual data bytes in the current record. Usually records have 16 data bytes. I don't know what the maximum number of data bytes is. It depends on the size of the data buffer in the EMON52.

Address Field¶

This is the address where the first data byte of the record should be stored. After storing that data byte, the address is incremented by 1 to point to the address for the next data byte of the record. And so on, until all data bytes are stored.

The address is represented by a 4 digit hex number (2 bytes), with the MSD first.

Data Field¶

The payload of the record is formed by the Data field. The number of data bytes expected is given by the Byte Count field.

Checksum¶

The checksum is a 16 bit result from adding all data bytes of the record together.

Size Multiplier¶

In general, binary data will expand in sized by approximately 3.8 times when represented with this format.