Fieldbus Conformance

Overview

Fieldbus conformance is not a single standard but the family of protocols that field devices actually speak: Modbus (Modbus Organization), BACnet (ISO 16484-5 / ASHRAE 135), DNP3 (IEEE 1815), and EtherNet/IP (the CIP protocol managed by ODVA). Tenders typically name the specific protocols a site already runs and expect a platform to interoperate with them directly. ControlBird implements all four natively, so it connects to existing PLCs, building controllers, meters, RTUs, and serial devices without a separate gateway or translator in between.

Key requirements

Conformant protocol behaviour

Speak each protocol to its specification, including the data model and the standard operations (register reads and writes, object reads, polls, and commands), so interoperability with third-party devices is reliable rather than best-effort.

Native addressing model

Address points the way each protocol defines them: Modbus register and coil addresses, BACnet object and property identifiers, DNP3 object groups and indexes, and EtherNet/IP tag names.

Both sides of the exchange

Act as the initiating side (client or master) and, where the deployment needs it, as the responding side (server or outstation), so the platform fits whether it is polling devices or being polled.

Field transports

Support the physical and transport bindings used in the field: Ethernet/TCP and serial RS-485 / RS-232, plus the building-automation and SCADA transports specific to each protocol.

How ControlBird aligns

Modbus (TCP and RTU)

Acts as a Modbus client over both TCP and serial RTU, and as a Modbus TCP server. Supports the standard function codes for coils, discrete inputs, and input and holding registers, with configurable data types and byte and word order, and per-mapping poll intervals.

BACnet (IP and MS/TP)

Acts as both a BACnet client and server over BACnet/IP and MS/TP serial. Discovers devices through the Who-Is and I-Am handshake, covers the common object and property types, and receives change-of-value subscriptions with automatic fallback to polling.

DNP3 (master and outstation)

Acts as a DNP3 master and as an outstation over TCP, serial, and TLS. Supports integrity and event polling, unsolicited responses by event class, and both direct-operate and select-before-operate commands, with object quality flags carried through.

EtherNet/IP (CIP)

Acts as an EtherNet/IP client for Allen-Bradley ControlLogix and CompactLogix controllers, using tag-based CIP addressing to read and write controller and program-scope tags, including structure members and array elements.

Scope and availability you should plan around

Roles are not symmetric across every protocol: the Modbus server is TCP only, and EtherNet/IP is client only. For transport security, EtherNet/IP has no in-transit encryption and DNP3 master TLS does not provide end-to-end confidentiality, so segment those networks or run them over a VPN. Modbus is available in every edition; BACnet, DNP3, and EtherNet/IP are part of the Cloud and Enterprise editions. We state these limits up front so they can be checked against a tender’s device list.