Modbus Register Map; Modbus Message Example - E+E Elektronik EE160 User Manual

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
Read register: function code 0x03
Temperature T
Relative humidity RH, Uw
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
Read register: function code 0x03
Temperature T
Relative humidity RH, Uw
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:
See Application Note Modbus AN0103 (available at www.epluse.com/EE160)
Request [Hex]:
Response Hex]:
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
Byte 3
Example:
Byte 1 (Register 2 - Hi)
41
10
Unit
°C, °F 3)
% RH
Unit
°C, °F 4)
% RH
www.modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf
Modbus ID Function
address code
F5 03
Modbus ID Function Byte
address code count
F5 03
MMMMMMMM
Byte 4
Response [Hex]
Byte 2 (Register 2 – Lo)
BA
Register number
1)
26
28
Scale Register number
1)
100 301
100 302
Starting Starting
address Hi address Lo
00 19
Register 1 Register 1
value Hi value Lo
04 51 F0
SEEEEEEE
Byte 1
Byte 3 (Register 1 - Hi)
51
User Manual EE160 Humidity and Temperature Sensor for HVAC Applications
[Dec] Register address
0x19
0x1B
[Dec] Register address
2)
0x12C
0x12D
No. of No. of
register Hi register Lo
00 02
Register 2 Register 2
value Hi value Lo
41 BA
EMMMMMMM
Byte 2
Value in decimal
Byte 4 (Register 1 - Lo)
F0
[HEX]
2)
[HEX]
3)
CRC
01 0F
CRC
98 10
23.290008