Configuration Registers - GMP251

GMP251 User Guide

Document code
M211799EN
Revision
G
Language
English (United States)
Product
GMP251
Document type
User guide
CAUTION Default power-up values (registers 513-519) are written into non-volatile EEPROM memory. The EEPROM memory implementation has a limit of 30000 writes, and is intended to be used only when saving long-term or permanent configurations. Use the volatile memory (registers 521 … 527, values cleared on power-up) for non-permanent configurations (for example, if the probe is used in a system that regularly updates the compensation values).
Table 1. Modbus Configuration Data Registers (Writable)
Register Number (Decimal) Address (Hexadecimal) Register Description Data Format Unit / Valid Range
513 0200hex Power-up value for pressure compensation 32-bit float hPa

700 ... 1500 hPa

Operating <1.5 bar

(Init/default: 1013.25)
515 0202hex Power-up value for temperature compensation 32-bit float °C

-40 ... +80

(Init/default: 25)
517 0204hex Power-up value for humidity compensation 32-bit float %RH

0 ... 100 %

(Init/default: 0)
519 0206hex Power-up value for oxygen compensation 32-bit float %O2

0 ... 100 %

(Init/default: 0)
521 0208hex Volatile (value cleared at probe reset) pressure compensation 32-bit float Range 700 ... 1500 hPa

(Init copied from power-up value)

523 020Ahex Volatile (value cleared at probe reset) temperature compensation 32-bit float Range -40 … +80 °C

(Init copied from power-up value)

525 020Chex Volatile (value cleared at probe reset) humidity compensation 32-bit float Range 0 … 100 %RH

(Init copied from power-up value)

527 020Ehex Volatile (value cleared at probe reset) oxygen compensation 32-bit float Range 0 … 100 %O2

(Init copied from power-up value)

769 0300hex Modbus address 16-bit integer Valid range 1 … 247 (default: 240)
770 0301hex Serial speed enum Valid range 4800 … 115200

0 = 4800

1 = 9600

2 = 19200

3 = 38400

4 = 57600

5 = 115200

(default: 2 (19200))
771 0302hex Serial parity enum

0 = None

1 = Even

2 = Odd

(default: 0 (None))
772 0303hex Serial stop bits 16-bit integer Valid range 1...2

(default: 2)

773 0304hex Pressure compensation mode enum

0 = Off

1 = On

(default: 1 (On))
774 0305hex Temperature compensation mode enum 0 = Off

1 = Given

2 = Measured

(default: 2 (Measured))
775 0306hex Humidity compensation mode enum 0 = Off

1 = On

(default: 0 (Off))
776 0307hex Oxygen compensation mode enum 0 = Off

1 = On

(default: 0 (Off))
777 0308hex CO2 filtering factor 16-bit integer Valid range 0 ... 100

(default: 100 (no filtering)).

For information on setting the filtering factor, see Filtering Factor on page 1.
To apply an accurate relative humidity compensation (775), you must also enable temperature compensation (774) and pressure compensation (773).