Vaisala GMP231 - Manual (Page 65)

Chapter 5 _______________________________________________________________ I2C Interface
VAISALA ________________________________________________________________________ 63
Get_Parameter_Info
Get_Parameter_Info command (ID 83h) reads the properties of a single
parameter from the GMP231. The command is useful for adapting to
parameters that have been added in a new software version. If the
requested parameter ID is not valid, data type Unknown Parameter ID
is returned.
Table 30 Get_Parameter_Info Invoke Message
Message Segment Length Content
I
2
C address 1 byte I
2
C address (write)
Command ID 1 byte Always 83h
Device address 1 byte See Table 13 on page 51
Frame length 1 byte Always 06h.
Data 1 byte Parameter ID
Checksum 2 bytes See section Checksum on page 56
Table 31
Get_Parameter_Info 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.
Command ID 1 byte Always 83h
Device address 1 byte See Table 13 on page 51
Frame length 1 byte Always 12h.
Data 1 byte Parameter ID
1 byte Parameter datatype. See Table 32
below.
1 byte Parameter length in bytes.
1 byte Parameter persistence. Describes if the
parameter value is volatile (lost at reset)
or non-volatile (survives reset). See
Table 33 below.
8 bytes Parameter name. If name is shorter
than 8 bytes, extra bytes are filled with
00h.
Checksum 2 bytes See section Checksum on page 56
Table 32
Parameter Data Types
Code Meaning
0
Unknown parameter ID
1 Byte
2 Integer (16-bit)
3 Unsigned Integer (16–bit)
4 Float (32-bit)
5 String
Table 33
Parameter Persistence
Code Meaning
0
Void
1 Volatile
2 Non volatile