Vaisala GMP231 - Manual (Page 61)

Chapter 5 _______________________________________________________________ I2C Interface
VAISALA ________________________________________________________________________ 59
Get_Parameter
Get_Parameter command (ID 81h) reads parameter values. You can use
it to read both measurement results and operational parameters. If the
master tries to read more bytes than message size, the slave sends FFh
bytes.
Table 21 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 13 on page 51
Frame length 1 byte Always 06h
Data 1 byte ID of parameter to be read
Checksum 2 bytes See section Checksum on page 56
Table 22
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 56. 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 13 on page 51
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 56