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3.7.3
EE895 Connected to a KNX Bus
Fig. 13
Example KNX Bus
Pin 7 - ISEL is connected to the ground → the EE895 features I
The VCC_EM and the VCC_IO are connected to the typical 5 V bus voltage.
The I
C host keeps the EE895 enabled with the pin 3 – EN and can read the values at any time,
2
pin 6 - RDY is not used.
4
Digital Interface
The EE895 features standard I
The interface selection is made with pin 7 – ISEL, see Tab. 2 on page 9.
On both interfaces, I
PDUs).
Please note: Modbus implementation details and request/response examples are described in detail in
the Modbus Application Note AN0103 (available at www.epluse.com/EE895).
4.1
I
C Interface
2
The EE895 supports the standard I²C specification. For detailed information about the I
please refer to NXP document „I²C-bus specification and user manual", Rev. 6, 4 April 2014:
www.nxp.com/docs/en/user-guide/UM10204.pdf
The I
C interface simultaneously supports two protocols on two different slave addresses:
2
• Modbus over I
• I
C simplified
2
These addresses are fixed, they cannot be changed by the user.
4.1.1
Modbus Protocol Over I
I
C slave address: 0x5F
2
The I
C interface encapsulates the data according Modbus PDU packets, including CRC:
2
S
Slave Address
S
Slave Address
Every byte of the Modbus PDU and the Modbus CRC must be acknowledged
(according to I
C specification, not shown above).
2
12
C and UART interfaces.
2
C and UART, the data is encapsulated in Modbus Protocol Data Units (Modbus
2
C
address 0x5F
2
address 0x5E
C Interface
2
W
A
Request: Modbus PDU + Modbus CRC
R
A
Response: Modbus PDU + Modbus CRC
C interface.
2
User Manual EE895 Miniature Sensor Module for CO
C interface,
2
P
P
, T and p
2
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