Adjust - GMP231

GMP231 User Guide

Document code: M211501EN
Revision: E
Language: English
Product: GMP231
Document type: User guide

Adjust command (ID 84_hex) controls the user adjustment sequence of CO₂ measurement.

Table 1. Adjust invoke message
Message segment	Length	Content
I²C address	1 byte	I²C address (write)
Command ID	1 byte	Always 84_hex
Device address	1 byte	See Table 2.
Frame length	1 byte	Varies according to data length, 07_hex ... 0B_hex.
Data	1 byte	Adjustment subcommand. See Table 3.
	1 byte	Parameter to be adjusted. See Table 4.
	4 bytes	Value of parameter. Used only with subcommands 2 and 3.
Checksum	2 bytes	See Checksum.

Table 2. Adjust response message
Message Segment	Length	Content
I²C address	1 byte	I²C address (read)
Status	1 byte	See Status byte.
Command ID	1 byte	Always 84_hex
Device address	1 byte	See Table 2.
Frame length	1 byte	Always 07_hex.
Data	1 byte	Return code. See Table 5.
Checksum	2 bytes	See Checksum.

Table 3. Adjustment subcommands
Code	Adjustment operation
0	Start 1 point adjustment
1	Start 2 point adjustment
2	Record measured point 1, reference value is given in parameter
3	Record measured point 2, reference value is given in parameter
4	Cancel adjustment (previous adjustment is reverted)
5	End (adjustment is saved and new values are taken in use)
6	Revert to factory calibration (clear user adjustment)

Table 4. Adjustment parameters
Code	Purpose
0	All parameters (valid with revert to factory calibration)
1	CO₂

Table 5. Adjustment return codes
Code	Meaning
0	OK
1	Function not supported
2	Sequence error
3	Recorded-Reference difference too large
4	2-point adjustment: Points too close
5	Given reference value is invalid