9
KNX serial card
+030220326- rel. 1.0 - 16.05.2017
ENG
3. COMMUNICATION SPECIFICATIONS
4. USING ETS5
3.1.2
Device addresses
In a KNX network, each device must have a unique address. The addresses
are assigned to the devices over the network connection using the ETS
software.
ETS5 is used to define, even before connecting to the bus, the layout
of the entire system, adding all the devices that make it up. The ETS
software automatically assigns an address to each device, however
where necessary these can be changed manually. The values of the
addresses are saved in a project file. During the first stage of installation,
when connecting the personal computer to the bus, the actual device
addresses need to be set. This operation is performed by activating the
“download address” procedure for each device and then pressing the
button on the controller being configured. In this way, each device is
identified and configuration can continue.
3.2 Modbus communication
The card acts as a Modbus RTU master in relation to the pCO, using the
following function codes:
•
01 Read coil status
•
02 Read discrete inputs
•
03 Read holding registers
•
04 Read input registers
•
05 Force single coil
•
06 Preset single register.
The controller address and baud rate can be configured using the ETS
software. For the e-drofan controller the address must be set to 1 and the
baud rate must be 9600 baud. For the other controllers, the address and
baud rate must be set in line with the chosen configuration.
3.1 KNX communication
The mode supported by the Carel Konnex card is TP1 9.6 kbits/s System
mode.
Operation of a KNX network requires a specific bus power supply that
supplies the bus 29 volts DC. The network is configured using a personal
computer (Windows OS) running the ETS5 program, and an interface
between the USB/Ethernet port and the KNX bus.
3.1.1
KNX datapoint
In the KNX standard, information is transferred between devices via data
structures called “datapoints”; the term “datapoint” can be considered a
synonym of shared variable. The connection is created by assigning the
“group address” to each datapoint, independently of the device address.
To “share” a set of variables between multiple devices, these must have the
same group address and be the same type (bit, byte, word, etc.…). This
mode is called System mode and in fact creates “free binding” between
the variables on the various devices.
Multicast data transmission is used: the node that has a certain output
datapoint (transmission flag activated) sends the network a packet
that will be received at the same time by all the devices with an input
datapoint of the same type, with the same group address as the sender.
Example of communication between datapoints:
GROUP ADDRESS 1/1/1: shared among device #1, #4 and #8
GROUP ADDRESS 1/1/2: shared among device #1and #8
GROUP ADDRESS 1/2/3:
shared among device #4 and #8
1/2/3
Device #4
Device #1
Device #8
1/1/1
1/1/2
1/1/6
1/1/1
1/2/3
1/1/2
1/1/1
Fig. 3.a
The ETS5® program is the software solution for designing and setting up
a KNX system. ETS5® is a software tool that is independent of individual
manufacturers and is marketed by KNX International (www.knx.org).
ETS5® can be used to design, commission and run diagnostics on KNX
systems installed with KNX devices made by different manufacturers.
For information on how to the use ETS5, see the dedicated manual
available at www.knx.org.
