Uart Interface; Modbus Protocol Over Uart Interface - E+E Elektronik EE895 User Manual

The measured data is available as a 16 bit integer and is expressed in SI units:
Measurand
CO average
2
T
p
Tab. 7 Data availability from the EE895 Miniature Sensor Module
Example for reading all measurands (7-bit address shifted):
Request [Hex]: S BC 00 P
Slave address
START
7-bit shifted
S BC
Response [Hex]: S BD 03 B0 0A B7 8D 00 26 70 P
Slave address
START
7-bit shifted
S BD
*) reserved for future use
Conversion:
Measurand
CO
2
T
p
Tab. 8 Interpretation of data from the response
Example for reading the air pressure value (7-bit address shifted):
Request [Hex]: S BC 06 P
Slave address
START
7-bit shifted
S BC
Response [Hex]: S BD 26 70 P
Slave address
START
7-bit shifted
S BD
Conversion:
Measurand
p
Tab. 9 Interpretation of data from the response
4.2

UART Interface

4.2.1

Modbus Protocol Over UART Interface

Modbus slave address: 0x5F
The interface settings are: Baud rate 9600, 8 Data, No parity, 1 Stop bit (9600 8 N 1)
The slave address and the interface settings are fixed, they cannot be changed by the user.
The EE895 module shall be addressed according to the specification "Modbus over serial line V1.02",
see http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf
14
Register pointer Unit
0x00 ppm
0x02 °C
0x06 mbar
Register
STOP
pointer
00 P
CO CO
2 2
high byte low byte high byte
03 B0 0A
Response [Hex]
0x03B0
0x0AB7
0x2670
Register
STOP
pointer
06 P
p p
STOP
high byte low byte
26 70
Response [Hex]
0x2670
T T res.*)
low byte high byte
B7 80
Response [Dec]
944
2743
9840
P
Response [Dec]
9840
User Manual EE895 Miniature Sensor Module for CO
Scale
1:1
1:100 *
1:10 **
* Example: 2575 means 25.75 °C
** Example: 10130 means 1013 mbar
res.*) p p
low byte high byte low byte
00 26 70
Value
944 ppm
27.43 °C
984.0 mbar
Value
984.0 mbar
.
STOP
P
, T and p
2