MODBUS RTU Gateway’s Parameters


Name (field): enter the title for your KNX gateway;

Protocol (drop down): choose the protocol to match with the gateway;

Enable (check box): it allows to enable /disable the selected gateway;

Select device (drop down): select the type of device and the port that you want to use;

Address (field): connection address (for X1 and X3 it sets the RS485 port to use)

Port (field): TCP port (for X1 and X3 it’s not needed);

Component’s parameters

Connection timeout: sets the timeout milliseconds to wait for the connection (only valid when TCP gateway is used)

Read interval: delay between each read on the bus

Receive timeout: raise an error after this milliseconds timeout when a request does not receive a correct answer in time.

Connection CRC error timeout: raise an error after this time when a message is received but with CRC error

Wait for interval if frame failed: delay before sending again messages after an error

Wait for interval if frame success: delay before sending a message

Byte order: define the protocol byte order (MSB = Most Significant Byte before) (LSB = Least Significant Byte before))

ASCII transform: must be checked when the protocol is defined as ASCII format

The RTU protocol needs some more information to set up the serial communication:

Baudrate: 300 – 115.200

Bits: 5,6,7,8

Parity: Odd, Even

Stop bits: 1,2

If the device uses the serial communication directly (X1, X3) you can define them with the corresponding drop-down selectors.

If an IP to RS485 is used you have to read the manual of your gateway to setup it, usually from a webpage of the gateway

On Raspberry PI if you attach a USB device as gateway usually the address will become /dev/ttyAMA0

Here is the connector of EVE X1 explained: