Protocols

A protocol defines how Koios communicates with an external device or data source. When you create a device, you choose a protocol. This determines the connection settings you'll need to provide and the types of tags you can create.

Protocol cannot be changed after creation

The protocol is locked once a device is created. If you need a different protocol, create a new device and recreate the tags.

Supported Protocols

Protocol	Use Case	Configuration Guide
OPC-UA	PLCs, SCADA systems, historians, and modern industrial equipment	OPC-UA Device
Modbus TCP	Sensors, meters, and simple controllers using register-based addressing	Modbus TCP Device
EtherNet/IP	Allen-Bradley Logix controllers and generic CIP-compliant devices	EtherNet/IP Device
SOAP	RDM HVAC controllers via web services	SOAP Device
REST	CAREL BOSS building management systems	REST Device
Microsoft SQL	Querying data directly from SQL Server databases via ODBC	Microsoft SQL Device

Protocols are system-defined. You cannot add or delete them. Protocols you don't use can be hidden from the device create flow with the visibility toggle on the Protocols list or detail page.

Protocol Details

OPC-UA

OPC Unified Architecture (shown as OPC UA in the app) is the modern standard for industrial data exchange. It provides a platform-independent, service-oriented architecture for communicating with PLCs, SCADA systems, historians, and other industrial equipment.

Koios connects as an OPC-UA client and supports:

Server discovery: browse your network for available OPC-UA servers and endpoints
Security modes: None, Sign, or Sign & Encrypt
Security policies: Basic128Rsa15, Basic256, Basic256Sha256
Authentication: Anonymous or Username/Password
Node browsing: explore the server's address space to find and select tags

Modbus TCP

Modbus TCP is a widely-used protocol for communicating with sensors, meters, and simple PLCs over Ethernet. It uses a register-based addressing model where data points are identified by register type and address number.

EtherNet/IP

EtherNet/IP (shown as Ethernet/IP in the app) uses the Common Industrial Protocol (CIP) to communicate with industrial devices over standard Ethernet. Koios supports two device types under this protocol:

Logix Controller: connects to Allen-Bradley ControlLogix and CompactLogix controllers using tag-based addressing. Includes a tag browser for exploring the controller's tag database.
Generic CIP: connects to any CIP-compliant device (variable frequency drives, I/O modules, non-Allen-Bradley equipment) using assembly-based addressing. Supports EDS file upload for structured browsing of device data.

SOAP

The SOAP (Simple Object Access Protocol) implementation in Koios is designed for RDM (Resource Data Manager) controllers. RDM devices expose a SOAP-based API for reading and writing HVAC parameters.

REST

The REST protocol currently connects specifically to CAREL BOSS building management systems. The device-type selector defaults to BOSS, and no other REST device type is implemented, so request formatting and response parsing are BOSS-specific. Koios sends HTTP requests to the configured BOSS endpoint and parses the response to extract tag values.

Microsoft SQL

Microsoft SQL devices allow Koios to query data from SQL Server databases using ODBC. Each tag on an SQL device executes a SQL query on every scan cycle and stores the result as a live value. This is useful for integrating data from business systems, energy management platforms, or external historians.

Certificates

Some OPC-UA servers require certificate-based trust in addition to (or instead of) username/password authentication. See OPC-UA Certificates for details on managing certificates in Koios.

What's Next

Create a Device: add a device on the protocol you picked
OPC-UA Certificates: manage certificate-based trust for OPC-UA servers

Backing Up Docker Volumes OPC-UA Certificates