I 2 C Simplified Protocol - E+E Elektronik EE895 User Manual

The EE895 module supports repeated START or STOP conditions between the request packet and
the response packet. If a START condition and an address match are detected, the EE895 will stay
active until a STOP condition is received or an idle timeout of 500 ms occurs. This might increase the
power consumption and self-heating. The I
possible in case of a repeated START.
For the Modbus register map please refer to chapter 4.3, page 15.
Please note: The CRC16 shall be calculated including the unshifted slave address.
Example of command reading the temperature (floating point value) T = 25.30 °C from the register 0x3EA:
Request [Hex]: S BE 03 03 EA 00 02 E8 C5 P
Slave address
START
7-bit shifted
S BE
Response [Hex]: S BF 03 04 00 00 41 DC 74 3F P
Slave address
START
7-bit shifted
S BF
For decoding of float values stored according standard IEEE 754, please refer also to the Modbus
Application Note AN0103.
Example of Decoding:
Response [Hex]:
Byte 1
(Register 2 - Hi)
41
Please note: For obtaining the correct value, both registers have to be read with a single request.
The measured value can change between two Modbus requests. Exponent and mantissa may get
inconsistent in this case.
4.1.2 I C Simplified Protocol
2
I C slave address: 0x5E
2
This I²C protocol is intended for I
"EEPROM-like-mode".
The simplified I
in 8 subsequent registers, as 16 bit integers.
Slave address
0x5E
*) Reserved for future use
The read pointer is the first register to be set. Additional bytes are answered by the EE895 module
with NACK. If more bytes are read than the 8 registers, the EE895 answers with 0xFF
(i.e. the SDA line is not pulled down). If a START condition and an address match are detected, the
EE895 will stay active until a STOP condition is received or an idle timeout of 500 ms occurs.
User Manual EE895 Miniature Sensor Module for CO
Function Starting
code address Hi
03
Function Byte
code count
03 04
Byte 2
(Register 2 – Lo)
DC
C master reading the measured values from EE895 in
2
C does not support any error detection (such as CRC) and provides the measured data
2
0x00 0x01
CO CO
2 2
high byte low byte
, T and p
2
C master shall ensure that the data is retrieved as soon as
2
Starting No. of
address Lo register Hi
03 EA
Register 1 Register 1
value Hi value Lo
00 00
Byte 3
(Register 1 - Hi)
00
0x02 0x03
T T reserved*)
high byte low byte high byte
No. of
register Lo
00 02 E8
Register 2 Register 2
value Hi value Lo
41 DC 74
Byte 4
(Register 1 - Lo)
00
0x04 0x05 0x06
reserved*)
low byte high byte
CRC STOP
C5 P
CRC STOP
3F P
Decimal value
27.50
0x07
p p
low byte
13