E+E Elektronik EE160, User Manual, Page: 10 / 13

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User Manual EE160 Humidity and Temperature Sensor for HVAC Applications
4.5 Modbus Register Map
The measured data is saved as a 32 bit floating point values (data type FLOAT) and as 16 bit signed
integer values (data type INTEGER).
FLOAT 32 bit:
Parameter Unit Register number
1)
[Dec] Register address
2)
[HEX]
Read register: function code 0x03
Temperature T °C, °F
3)
26 0x19
Relative humidity RH, Uw % RH 28 0x1B
1) Register number starts from 1.
2) Register address starts from 0.
3) The choice of measurement units (metric or non-metric) is done at the time of ordering, see the ordering guide in the EE160 data sheet. It is not
possible to switch from metric to non-metric or vice versa by means of the EE-PCS.
INTEGER 16 bit:
Parameter Unit Scale
1)
Register number
2)
[Dec] Register address
3)
[HEX]
Read register: function code 0x03
Temperature T °C, °F 4) 100 301 0x12C
Relative humidity RH, Uw % RH 100 302 0x12D
1) Example: For scale 100, the reading of 2550 means a value of 25.5.
2) Register number starts from 1.
3) Register address starts from 0.
4) The choice of measurement units (metric or non-metric) is done at the time of ordering, see the ordering guide in the EE160 data sheet. It is not
possible to switch from metric to non-metric or vice versa by means of the EE-PCS.
4.6 Modbus Message Example
Example of Modbus RTU command for reading the temperature (float value) T = 23,290008 °C
from the register 0x19.
Device EE160; slave ID 245 [0xF5]
Reference document, chapter 6.3: www.modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf
See Application Note Modbus AN0103 (available at www.epluse.com/EE160 )
Modbus ID
address
Function
code
Starting
address Hi
Starting
address Lo
No. of
register Hi
No. of
register Lo
CRC
Request [Hex]: F5 03 00 19 00 02 01 0F
Modbus ID
address
Function
code
Byte
count
Register 1
value Hi
Register 1
value Lo
Register 2
value Hi
Register 2
value Lo
CRC
Response Hex]: F5 03 04 51 F0 41 BA 98 10
Decoding of floating point values:
Floating point values are stored according IEEE754 standard. The byte pairs 1, 2 and 3, 4 are inverted
as follows:
MMMMMMMM MMMMMMMM SEEEEEEE EMMMMMMM
Byte 3 Byte 4 Byte 1 Byte 2
Example:
Response [Hex] Value in decimal
Byte 1 (Register 2 - Hi) Byte 2 (Register 2 – Lo) Byte 3 (Register 1 - Hi) Byte 4 (Register 1 - Lo)
41 BA 51 F0 23.290008