Vaisala HMM105 - Manual (Page 14)

Technical Reference _________________________________________________________________
12 ________________________________________________________________ M211638EN-A
Get_Parameter
The Get_Parameter command (ID 81h) reads parameter values. You can
use it to read both measurement results and operational parameters. If the
number of bytes the master tries to read exceeds the message size, the
slave sends FFh bytes.
Table 13 Get_Parameter Invoke Message
Message Segment Length Content
I 2 C address 1 byte I 2 C address (write)
Command ID 1 byte Always 81h
Device address 1 byte See Table 5 on page 4
Frame length 1 byte Always 06h
Data 1 byte ID of parameter to be read
Checksum 2 bytes See section Checksum on page 9
Table 14 Get_Parameter Response Message
Message Segment Length Content
I 2 C address 1 byte I 2 C address (read)
Status 1 byte See section Status Byte on page 9. If
requested parameter ID was unknown,
NACK bit is set in the status byte.
Command ID 1 byte Always 81h
Device address 1 byte See Table 5 on page 4
Frame length 1 byte Varies according to data length,
07h ... 39h.
Data 1 byte ID of parameter
1 ... 50 bytes Value of parameter. If requested
parameter ID is unknown, these data
bytes are left out of the response.
Checksum 2 bytes See section Checksum on page 9