Vaisala GMP231 - Manual (Page 68)

User's Guide _______________________________________________________________________
66 ___________________________________________________________________ M211501EN-C
Two Point Adjustment
To perform a two point adjustment of CO
2
measurement using I
2
C
protocol, you must perform the following sequence:
1. Using the Adjust command, start 2 point adjustment for CO
2
.
2. Supply the low concentration CO
2
reference gas to the sensor and
wait for three minutes until the measurement has stabilized.
3. Using the Adjust command, record the first measured point and
give the first reference value.
4. Supply the high concentration CO
2
reference gas to the sensor and
wait for three minutes until the measurement has stabilized.
5. Using the Adjust command, record the second measured point and
give the second reference value.
6. Use the Adjust command to end the adjustment.
Data Registers
The register table describes all available parameters and their properties.
The properties are: parameter meaning, ID, name, data type, length and
persistence. Persistence defines if the parameter is saved in eeprom (non-
volatile memory) or in RAM. Make sure not to write excessively to the
eeprom, as it has a maximum lifetime of approximately 30000 cycles.
Data Formats
Table 39 Data Formats
Data type name Size (Bytes) Other
Byte 1 Value range 0...255
Integer 2 Value range -32768...32767.
Unsigned integer 2 Value range 0…65535
Long integer 4 Value range
−2,147,483,648…2,147,483,647
Unsigned long integer 4 Value range 0…4,294,967,295
Float 4 According to IEEE-754. Nan
(7FC00000) is returned if no value
is available.
String Max. 50 All characters accepted
(00h…FFh)
NOTE Maximum string size refers to maximum communication buffer size.
The actual reserved storage space for each parameter can be seen in
Table 40 on page 67.
NOTE Integers and floating point numbers are sent LSB first.