📦 Sample — Building Automation Fieldbusses

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🧠 Remarks and limitations

• This is a sample project demonstrating how to use various building automation fieldbus protocols with Beckhoff TwinCAT 3.
• Minimum TwinCAT version: 3.1.4024.74
• Each fieldbus protocol lives in its own PLC project within a single TwinCAT solution. They can be enabled or disabled independently.
• The DIOC (Fixsus) sub-project requires the third-party DiocLibrary from Upzio, which must be installed separately.
• BACnet Rev12 contains only an empty MAIN program and serves as a placeholder configuration.
• Hardware terminals (KL6301, KL6581, KL6781, KL6821, KL6831, EL6821, EL6851) must be present and configured in the I/O tree for the corresponding sub-project to function.

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🔧 Functionality Overview

BACnet_Rev14

Demonstrates BACnet/IP communication using the TwinCAT 3 BACnet Rev14 library. Creates a hierarchical BACnet object tree with buildings (Office, Production Plant, Warehouse), levels, and rooms, each containing analog input (AI) objects for temperature readings and analog value (AV) objects for setpoints.

• Uses FB_BACnet_Adapter for adapter state, FB_BACnet_View for hierarchy nodes, FB_BACnet_AI / FB_BACnet_AV for data points
• Requires a BACnet I/O Device configured in the TwinCAT project

DIOC_Fixsus

Controls a TP10 DIOC touch panel (Upzio/Fixsus) with LEDs, buttons, and environmental sensors (temperature, humidity, CO2, air quality).

• Uses FB_TP10 from the third-party DiocLibrary
• Requires {attribute 'TcCallAfterOutputUpdate'} and a 12 ms task cycle

EL6821_Tc3DALI

DALI lighting control via the EL6821 EtherCAT terminal using the TwinCAT 3 DALI library.

• Uses FB_EL6821Communication for terminal communication and FB_DALI102DirectArcPowerControl for dimming
• Sets DALI address 10 to power level 127 (mid-range) as an example

EL6851_DMX

DMX512 master and slave communication via the EL6851 terminal for stage/architectural lighting.

• Master (P_DMX_Master): sends up to 512 channels of DMX data using FB_EL6851CommunicationEx
• Slave (P_DMX_Slave): receives DMX channel data (default 64 channels, configurable)

KL6301_EIB_KNX

KNX/EIB communication via the KL6301 Bus Terminal for home and building automation.

• Uses KL6301 FB with physical address configuration and group address filtering (up to 8 filters)
• Demonstrates bit-level send/receive with FB_EIB_BIT_SEND / FB_EIB_BIT_REC and multiple trigger modes (manual, polling, on-change)
• Includes helper function F_EIB_GroupAddress to construct group addresses from main/sub/number

KL6581_EnOcean

EnOcean wireless sensor/switch communication via the KL6581 Bus Terminal.

• Uses FB_KL6581 for terminal communication and FB_Rec_RPS_Switch to decode 4-pushbutton rocker switch telegrams
• Supports up to 64 KL6581 terminals

KL6781_MBus

M-Bus (Meter-Bus) communication via the KL6781 Bus Terminal for reading energy meters and utility meters.

• Standard (P_MBus): uses FB_MBUS_EMU_32x7 to read operating hours, energy, power, and error status from a meter
• Fast (P_MBus_Fast): uses FB_MBUSKL6781 with global I/O variables for higher-speed polling (2 ms task)

KL6821_Tc2DALI

DALI lighting control via the KL6821 Bus Terminal using the older TwinCAT 2 DALI library.

• Uses FB_KL6821Config for digital input event configuration (watchdog, DI1/DI2 edges) and FB_DALIV2DirectArcPowerControl for dimming
• Demonstrates configuration of the KL6821 command buffer

KL6821_Tc3DALI

DALI lighting control via the KL6821 Bus Terminal using the TwinCAT 3 DALI library.

• Uses FB_KL6821Communication with embedded initialization link and FB_DALI102DirectArcPowerControl
• Simplified setup compared to the Tc2 variant

KL6831_SMI

SMI (Standard Motor Interface / Somfy) control for motorized blinds and screens via the KL6831 Bus Terminal.

• Uses FB_KL6831KL6841Config for digital input assignment, FB_SMIDown / FB_SMIUp for motor control, and FB_SMIDiagAll for diagnostics
• Supports priority-based Up/Down commands on DI1/DI2

Modbus_RTU

Modbus RTU serial communication in both master and slave roles.

• Master (P_ModbusRTU_Master): sequential state machine reading input/holding registers and writing to slave devices via ModbusRtuMasterV2_PcCOM (also supports KL6x5B/KL6x22B variants)
• Slave (P_ModbusRTU_Slave): exposes input registers (256 words), output registers (256 words), and memory area (2048 words) at device address 17

Modbus_TCP

Modbus TCP/IP master communication over Ethernet.

• Uses FB_MBReadInputs and FB_MBWriteRegs to communicate with a Modbus TCP slave at a configurable IP address and port
• Demonstrates reading input registers and writing holding registers

Task architecture

Task	Cycle	Priority	Runs
PlcTask_EIB_KNX	10 ms	20	KL6301_EIB_KNX
PlcTask_Tc3DALI	10 ms	21	KL6821_Tc3DALI
PlcTask_EnOcean	10 ms	22	KL6581_EnOcean
PlcTask_SMI	10 ms	23	KL6831_SMI
PlcTask_DMX	10 ms	24	EL6851_DMX
PlcTask_Tc2DALI	10 ms	25	KL6821_Tc2DALI
PlcTask_BACnetRev12	10 ms	26	BACnet_Rev12
PlcTask_BACnetRev14	10 ms	27	BACnet_Rev14
PlcTask_ModbusRTU	10 ms	28	Modbus_RTU
PlcTask_ModbusTCP	10 ms	29	Modbus_TCP
PlcTask_MBus	10 ms	30	KL6781_MBus
PlcTask_MBus_Fast	2 ms	9	KL6781_MBus (fast polling)
PlcTask_DIOC	12 ms	31	DIOC_Fixsus
PlcTask (EL6821)	10 ms	32	EL6821_Tc3DALI

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🧪 Example

PROGRAM MAIN
VAR
END_VAR

P_BacnetRev14();

PROGRAM P_ModbusRTU_Master
VAR
    fbModbus    : ModbusRtuMasterV2_PcCOM;
    Rcv         : ARRAY[0..100] OF WORD;
    Step        : INT := 0;
END_VAR

CASE Step OF
    0:  // Read 6 input registers from device 10, starting at register 0
        fbModbus.UnitID         := 10;
        fbModbus.Quantity       := 6;
        fbModbus.MBAddr         := 0;
        fbModbus.cbLength       := SIZEOF(Rcv);
        fbModbus.pMemoryAddr    := ADR(Rcv);
        fbModbus.ReadInputRegs  := TRUE;
        Step := 1;
    1:  // Wait for completion
        fbModbus.ReadInputRegs  := FALSE;
        IF NOT fbModbus.BUSY THEN
            Step := 0;
        END_IF
END_CASE

fbModbus();

Adapt each example by replacing device addresses, register maps, DALI short addresses, or group addresses with values matching your field installation.

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🧠 Notes

• The DIOC sub-project requires the TcCallAfterOutputUpdate attribute on MAIN and a 12 ms task cycle for correct communication timing with the TP10 panel.
• The KL6301 EIB/KNX project uses a GVL_IO with 24-byte input/output arrays mapped to the terminal process data; the KL6781 M-Bus fast variant similarly uses a GVL_IO for shared I/O structures.
• Modbus RTU master code includes commented-out variants for KL6x5B and KL6x22B Bus Terminals — uncomment the appropriate FB type for your hardware.
• The BACnet Rev14 sub-project creates all BACnet objects dynamically at runtime via PLC code; the BACnet I/O Device must be configured in the TwinCAT I/O tree first.
• For M-Bus fast polling, the task runs at 2 ms (priority 9) to ensure timely serial communication with the KL6781 terminal.

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🔢 Additional information

Required libraries

Library	Vendor	Purpose
Tc2_Standard	Beckhoff Automation GmbH	Standard PLC functions (all projects)
Tc2_System	Beckhoff Automation GmbH	System functions (all projects)
Tc3_Module	Beckhoff Automation GmbH	Module interface (all projects)
Tc3_BACnetRev14	Beckhoff Automation GmbH	BACnet Rev14 protocol
Tc3_BA2_Common	Beckhoff Automation GmbH	BA2 common types for BACnet Rev14
Tc2_DALI	Beckhoff Automation GmbH	DALI v2 protocol (KL6821 Tc2)
Tc3_DALI	Beckhoff Automation GmbH	DALI 102 protocol (KL6821/EL6821 Tc3)
Tc2_DMX	Beckhoff Automation GmbH	DMX512 protocol (EL6851)
Tc2_EIB	Beckhoff Automation GmbH	EIB/KNX protocol (KL6301)
Tc2_EnOcean	Beckhoff Automation GmbH	EnOcean wireless protocol (KL6581)
Tc2_MBus	Beckhoff Automation GmbH	M-Bus protocol (KL6781)
Tc2_SMI	Beckhoff Automation GmbH	SMI motor protocol (KL6831)
Tc2_ModbusRTU	Beckhoff Automation GmbH	Modbus RTU serial protocol
Tc2_ModbusSrv	Beckhoff Automation GmbH	Modbus TCP server/client
DiocLibrary	Upzio	DIOC TP10 touch panel (third-party)
Tc2_DataExchange	Beckhoff Automation GmbH	Data exchange (BACnet Rev14)
Tc2_IoFunctions	Beckhoff Automation GmbH	I/O functions (BACnet Rev14)

Supported platforms: x64 (64-bit)

Minimum TwinCAT version: 3.1.4024.74

License: BSD Zero Clause