KNX to MODBUS/RS485/RS232 Protocol Conversion Gateway Manual

Function Introduction:

1. ETS configuration interface.
2. The KNX bus provides direct power supply.
3. supportsKNX<->MODBUSmaster or slave mode conversion, with a maximum support of 500 registers. Supports value conversion of any bit length (up to 16 bits). Support configuring multiple identical registers simultaneously. Only supports instructions 0x03, 0x04, 0x06, and 0x10.
4. supportsKNX<->RS485conversion of any instruction (up to 24 bytes) to each other. The conversion value can be fixed or follow the data in the 485 instruction. Supports a maximum of 100 instructions.
5. supportsKNX<->RS232to convert any instruction (up to 24 bytes) to each other. The conversion value can be fixed or follow the data in the 232 instruction. Supports a maximum of 100 instructions.
6. supports 100 sets of logic input and output, including functions such as delay and 2-point logic control output.

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MODBUS Configuration

1.Modbus Communication Parameter Configuration

①Bps for Modbus (Set Baud Rate):Supports 2400, 9600, 19200, 38400, 56000, 115200, 128000, 256000.

②.Modbus master-slave mode selection:Slave mode: Slave mode, Host modeHost mode.

③.Modbus address (decimal) The address setting of the local machine in Modbus slave mode.

④.(Host only)Host mode read/write timeout (* 100ms):In host mode, when reading slave devices, the timeout time for waiting for a response from the slave is set to 5, which represents 500ms and cannot be less than 200ms. It is recommended to wait for 500ms or more, and the default is 500ms.

⑤.Number of Modbus registers enabled:Enable register configuration.

2.Modbus Register Configuration

①.Configuration precautions:Register addresses should be sorted in ascending order as much as possible according toascending orderconfiguration. In host mode, all registers of the same device are placed together and arranged in ascending order. This configuration allows the gateway to read the slave registers at once instead of reading them one by one, greatly improving efficiency.

② Enable reg:Active means enabled, inactive means not enabled.

③ Remark Name:You can label what the register corresponds to according to your needs.

④ Slave Address (Host Only):Set the address of the slave that needs to be read (decimal)).

⑤ Modbus register address: decimal.

⑥ Data type (dpt):KNX object data type.

⑦ Modbus Register Type:Hold Register - Modbus Host can read and write, Input Register - Modbus Host can only read, Coil Status - Modbus Host can read and write.

⑧ Time interval (host only):The time interval for reading each register in host mode, set to 0 by default.

⑨ Instruction selection (host only):Instruction selection for reading registers, 0X03H/0X04H/0X06H/0X10H/0X01H/0X02H/0X05H/0X0FH

⑩ Number of registers (host only):You can choose to read both registers 1 and 2 together, merge them, and forward them to KNX.

• ①Data format (host only):can choose the high byte first and high byte second modes, and set according to the specific data format.
• ② Send once for every value change:Set 0 to forward regardless of the change, set 1 to forward when the value changes by 1 (suitable for switch values), and set 10 to forward only when the current value changes by 210.
• ③ The bits that need to be converted:are the values of which bits in the register are taken and forwarded to KNX. Similarly, when KNX is transferred to the Modbus register, the values of the other bits remain unchanged. As shown in the figure below, 1 is set to represent hexadecimal 0x0001, which forwards the lowest bit data. If the value of the register is 0x1231, KNX forwards 1. If the value of the register is 0x1230, KNX forwards 0. The default value is 65535, which is 0xFFFF, which forwards all 16 bit values.
• ④ KNX to Modbus Data Conversion:This is a multiple used to process data conversion, for example: assuming the set value is 2, the KNX end receives data of 5, and the Modbus register receives data of 10; A negative number represents one part, such as -2. If the value received from KNX is 10, then the data in the Modbus register is 5. In application scenarios such as temperature conversion, most temperature values in Modbus are accurate to one decimal place, but KNX is accurate to two decimal places, so there is a difference of 10 times between them. You can set -10 to correct the temperature value. The default value is 1, and the original data is forwarded.

RS485 configuration

RS485 communication parameter configuration

①Bps for RS485:Set the baud rate of the RS485 bus.

②.Stop bit for RS485:Stop bit setting, only supports 1-bit and 2-bit.

③.Data bit for RS485:Data bit setting, only supports 8-bit and 9-bit.

④.Check bit for RS485:Check bit setting, only supports odd check and even check or no check.

⑤.Crc Check (0- No Check):provides a multi criteria CRC check algorithm and offers length selection for selecting CRC check source data.

⑥.Calculate CRC from the nth BYTE:Set the starting position of CRC.

⑦.Last BYTE deadline for settlement CRC:Set the end position of CRC.

⑧.Message reception timeout time (N character time):The time when RS485 bus recognizes the end of a frame, the time of one character * N.

⑨RS485 bus message sending interval (. ms):The minimum time interval for this device to send one frame of message to the bus.

⑩.RS485 channel number enable.

RS485 Command Configuration

①Remark Name:You can label what this instruction corresponds to according to your needs.

②.Data format of KNX (dpt):Data type of KNX object.

③.Does KNX send the message to RS485 after receiving it.

④.After receiving the message, does RS485 forward it to KNX.

⑤.Forwarding method:After receiving the correct instruction from the RS485 bus, select the value to forward to KNX. Forward the received value, then forward the data at the position replaced by XX in the instruction; Forward fixed values and send the set values on KNX.

⑥.Data forwarding settings:Refer to the seventh point of Modbus register configuration.

⑦.Instruction Content:The instruction is input in hexadecimal format, separated by spaces between each byte, and uses the letter XX to represent the data that needs to be converted to KNX. All instruction contents are case insensitive.

RS232 configuration

RS232 configuration is the same as RS485.

Function Configuration

Global Configuration

Channel Quantity: Maximum of 100.

Fun parameter configuration

① Enable the current function function.

② Function selection:Delay function provides the function of delayed sending, while 2-point logic function provides a simple 2-point control logic (triggering one operation above set point A and another operation below set point B).

③ Object dpt:Configure the required data type.

④ (Delay) Delay (seconds):0 represents no delay, 0~255.

⑤ (Delay) Delay (milliseconds):0 represents no delay, 0-255.

⑥ (2-point) High threshold setting:When the input value is higher than the set value, after a delay of the set time, send the value parameter set when it is higher than the high threshold.

⑦ (2-point) Low threshold setting:When the input value is higher than the set value, after a delay of the set time, send the value parameter set when it is lower than the low threshold.

⑧(2-point) Out. Object dpt:Control the data format of the output object:

⑨(2-point) Send value above high threshold:

⑩(2-point) Send value below low threshold:

• (2-point) Delay time (. min):Time setting for delayed output, in minutes.
• (2-point) Delay Time (. sec):Set the delay output time in seconds.
• Note: When the input value exceeds the high threshold and a value below the high threshold is received again within the delay time, the transmission will be canceled. The function remains the same when it is below the low threshold.

Example demonstration

RS485/RS232 to KNX conversion.

• (1) Set the hexadecimal instruction 0x12345678. When the converter receives a message from RS485/RS232 with the value 0x12345678, the KNX group address 1/0/4 sends the value of 50.
• can also be one of the values received by forwarding, using xx to represent the value that needs to be forwarded. When the converter receives a message of 0xabcdef0812 from RS485/RS232, the corresponding address 1/0/5 on the knx end will forward the 08 at xx position.

Video Tutorial

Basic Parameters and Installation

2.1 Electrical Parameters

2.2 Installation steps

1. Fixed equipment: clamped on a standard 35mm guide rail (similar to the installation method of an electric meter box).
2. Wiring:

• KNX: Connect the bus using twisted pair cables (similar to Ethernet cables).
• RS485/RS232: Use shielded twisted pair (anti-interference) to connect the equipment.

1. Indicator light:

• Green light constantly on: power supply is normal.
• Red flashing: Configuring.

Example of Practical Application Scenarios

Scenario 1: Intelligent Building Lighting

• Equipment: KNX Lighting System+MODBUS Human Sensor.
• Logic:

1. Sensor detects unmanned → sends signal to gateway.
2. Gateway delay of 30 seconds → Turn off lights through KNX.

Scenario 2: Industrial Temperature Control

• Equipment: RS485 Temperature Sensor+KNX Air Conditioning Controller.
• Logic:

1. Sensor reports 28 ℃ → Gateway forwards to KNX.
2. KNX judgment>25 ℃ → send the "turn on air conditioning" command.

Frequently Asked Questions and Answers

Q1: What should I do if the indicator light is not on?

• Check if the KNX bus power supply is normal (21V-31V).
• Confirm if the wiring is loose.

Q2: Data forwarding unsuccessful?

• Check if the baud rate and parity are consistent with the device.
• Confirm whether the position ofXXin the instruction is correct.

Q3: Logical rules not triggered?

• Check if the threshold is set properly (e.g. ">30" is mistakenly written as "<30").
• Confirm if the address of the output object is correct.

Technical Parameters Summary