Industrial Routes Overview

Why Industrial Routes?

Bridge the gap between your PLCs and MQTT without custom middleware. Read sensor data, write setpoints, and integrate industrial equipment into your IoT pipeline—using a single, consistent configuration pattern across all supported protocols.

Industrial Protocol Integration

Industrial routes enable direct communication between your Coreflux MQTT broker and industrial automation equipment. Read data from PLCs, write setpoints, and bridge the gap between IT and OT systems - all through standardized LoT (Language of Things) syntax.

Like a translator at an international meeting. Industrial routes speak both PLC (Modbus, S7, OPC UA) and MQTT—so your broker can read sensor data and send commands without custom glue code.

Supported Protocols

Modbus TCP

Industry-standard protocol for PLCs and industrial devices over Ethernet.

Modbus Serial

RS-232/RS-485 serial communication with Modbus RTU devices.

Siemens S7

Native S7 protocol for Siemens S7-200/300/400/1200/1500 PLCs.

OPC UA

Unified Architecture for cross-platform industrial communication.

ADS (Beckhoff)

TwinCAT ADS protocol for Beckhoff PLCs with AutoDiscovery support.

Allen-Bradley

ControlLogix, CompactLogix, and other Rockwell Automation PLCs.

EtherNet/IP

CIP-based communication for Allen-Bradley and compatible devices.

FINS (Omron)

Omron FINS protocol for CJ/CS/CP series PLCs.

Protocol Comparison

Protocol	Transport	Use Case	Vendor
Modbus TCP	TCP/IP	Universal PLC communication	Multi-vendor
Modbus Serial	RS-232/485	Legacy devices, long distances	Multi-vendor
Siemens S7	TCP/IP	Siemens automation systems	Siemens
OPC UA	TCP/IP	Cross-platform, secure IIoT	Multi-vendor
ADS	TCP/IP	Beckhoff TwinCAT systems	Beckhoff
Allen-Bradley	TCP/IP	Rockwell Automation	Rockwell
EtherNet/IP	TCP/IP	CIP devices, explicit messaging	Multi-vendor
FINS	TCP/UDP	Omron PLCs	Omron

Common Architecture

All industrial routes share a common architecture with three key components:

1. Connection Configuration

Each protocol has specific connection parameters:

ADD <PROTOCOL>_CONFIG
    WITH HOST "192.168.1.100"
    WITH PORT 502
    // Protocol-specific options...

2. MAPPING with Polling

MAPPING Definition A MAPPING is a scheduled, continuous polling operation that automatically reads data from industrial devices (PLCs, Modbus devices, etc.) at regular intervals and publishes the values to MQTT topics.

Polls: industrial device at regular intervals (EVERY)
Reads: multiple data points (TAGs) in a single operation
Publishes: each TAG value to its own MQTT topic

In LoT, you define a MAPPING like this:

ADD MAPPING SensorGroup
    WITH EVERY 500 MILLISECONDS
    ADD TAG Temperature
        // TAG config...
    ADD TAG Pressure
        // TAG config...

Common MAPPING-level fields

These fields are available at the MAPPING level across all industrial protocols:

SOURCE_TOPIC

string

Base MQTT topic for publishing tag data. Each TAG publishes to {SOURCE_TOPIC}/{TAG_NAME}.

EVERY

string

required

Polling interval (e.g. 500 MILLISECONDS, 1 SECOND).

3. TAG Definitions

TAG Definition A TAG is an individual data point within a MAPPING that represents a specific variable or register in an industrial device.

Identifies: a specific memory address in the device
Transforms: raw value using scaling, offset, and engineering units
Publishes: to a dedicated MQTT topic
Monitors: changes using deadband filtering

TAG capabilities

Data transformation: Scaling, offset, min/max validation
Change detection: Deadband to filter noise
Formatting: Publish as JSON or raw value

In LoT, you define a TAG like this:

ADD TAG Temperature
    WITH ADDRESS "100"
    WITH DATA_TYPE "FLOAT"
    WITH SOURCE_TOPIC "plc/temperature"
    WITH SCALING 0.1
    WITH UNIT "°C"

Common TAG Parameters

These parameters are available across all industrial protocols:

Addressing

ADDRESS

string

required

Protocol-specific address (register number, variable path, NodeId, etc.).

ADDRESS_TYPE

string

Address type varies by protocol (e.g., HOLDING_REGISTER, DATABLOCK, SYMBOL).

Data Types

DATA_TYPE

string

required

Data type for the value. Common types: BOOL, INT16, UINT16, INT32, UINT32, FLOAT, DOUBLE, STRING.

Topics

SOURCE_TOPIC

string

Topic where PLC values are published. Subscribe here to receive sensor data.

DESTINATION_TOPIC

string

Topic to send write commands. Publish a value here to write it to the PLC (requires WRITABLE true).

Value Transformation

SCALING

double

Multiplier applied to raw value. Formula: published_value = (raw_value * SCALING) + OFFSET. Default: 1.0.

OFFSET

double

Value added after scaling. Default: 0.0.

DECIMAL_PLACES

integer

Number of decimal places in published value. Default: 2.

Filtering

MIN_VALUE

double

Minimum allowed value. Values below this are filtered out.

MAX_VALUE

double

Maximum allowed value. Values above this are filtered out.

DEADBAND

double

Minimum change required to publish a new value. Reduces network traffic for slowly changing values. Default: 0.0.

Publishing Options

PUBLISH_MODE

string

Output format: VALUE_ONLY (just the value) or JSON (structured object with metadata). Default: VALUE_ONLY.

UNIT

string

Engineering unit for documentation and JSON output (e.g., °C, bar, RPM).

DESCRIPTION

string

Human-readable description of the TAG.

Write Control

WRITABLE

boolean

Allow writing to this TAG via DESTINATION_TOPIC. Default: false.

Byte Ordering

BYTE_ORDER

string

Byte order for multi-byte values: BIGENDIAN or LITTLEENDIAN. Default: BIGENDIAN.

WORD_ORDER

string

Word order for 32-bit values: BIGENDIAN or LITTLEENDIAN. Default: BIGENDIAN.

4. SOURCE_TOPIC Configuration

There are two ways to configure where TAG values are published. Use group-level when you want consistent topic structure across all TAGs in a MAPPING; use individual TAG when you need custom paths per sensor (e.g., different namespaces for temperature vs pressure).

Group-level (Recommended)
Individual TAG

Define SOURCE_TOPIC at the MAPPING level. Each TAG automatically publishes to {SOURCE_TOPIC}/{TAG_NAME}.

ADD MAPPING ProductionLine
    WITH SOURCE_TOPIC "factory/line1"
    WITH EVERY 1 SECOND
    ADD TAG Temperature
        WITH ADDRESS "100"
        WITH DATA_TYPE "FLOAT"
    ADD TAG Pressure
        WITH ADDRESS "102"
        WITH DATA_TYPE "FLOAT"

Result: Temperature publishes to factory/line1/Temperature; Pressure publishes to factory/line1/Pressure.

Define SOURCE_TOPIC at each TAG level for custom topic structure.

ADD MAPPING ProductionLine
    WITH EVERY 1 SECOND
    ADD TAG Temperature
        WITH SOURCE_TOPIC "sensors/temp/line1"
        WITH ADDRESS "100"
        WITH DATA_TYPE "FLOAT"
    ADD TAG Pressure
        WITH SOURCE_TOPIC "sensors/pressure/line1"
        WITH ADDRESS "102"
        WITH DATA_TYPE "FLOAT"

Result: Temperature publishes to sensors/temp/line1; Pressure publishes to sensors/pressure/line1.

5. EVENT (On-Demand Operations)

Understanding on-demand operations in routes. EVENT Definition An EVENT is an on-demand operation that waits for messages on an MQTT topic, executes a specific action when triggered, and publishes the results back to another MQTT topic. Use EVENT when you need on-demand reads or writes (triggered by a message); use MAPPING for continuous polling. Syntax varies by protocol—see the protocol-specific docs (e.g., Modbus TCP) for details. In LoT, you define an EVENT like this:

ADD EVENT ReadOnDemand
    WITH SOURCE_TOPIC "plc/commands/read"
    WITH DESTINATION_TOPIC "plc/responses/read"
    WITH QUERY "<protocol_query>"

Common EVENT Parameters

These parameters are available across all industrial protocols for EVENT definitions:

SOURCE_TOPIC

string

required

MQTT topic where the EVENT listens for trigger messages. Publish a message here to execute the operation.

DESTINATION_TOPIC

string

required

MQTT topic where the EVENT publishes the result of the operation.

QUERY

string

required

Protocol-specific specification of the operation (read or write) and its parameters. Uses LoT object syntax. See each protocol’s documentation for supported operations.

When to Use MAPPING vs EVENT

Use the right acquisition pattern for the job:

	MAPPING (Cyclic)	EVENT (On-Demand)
Trigger	Automatic, on a timer (`WITH EVERY`)	Manual, via an MQTT message to SOURCE_TOPIC
Direction	Reads from device, publishes to MQTT	Reads or writes on command, publishes result
Best for	Dashboards, alarms, continuous telemetry	Operator commands, diagnostics, recipe downloads
Data volume	Constant stream at defined interval	Only when requested

Most real-world routes combine both patterns: MAPPING for continuous monitoring and EVENT for on-demand operations within the same DEFINE ROUTE.

Basic Example Pattern

Cyclic Only

This minimal pattern works across all industrial protocols for continuous data acquisition:

DEFINE ROUTE MyPLCConnection WITH TYPE <PROTOCOL_TYPE>
    ADD <PROTOCOL>_CONFIG
        WITH HOST "192.168.1.100"
        // Connection parameters...
    
    ADD MAPPING CriticalSensors
        WITH EVERY 100 MILLISECONDS
        ADD TAG Temperature
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/temperature"
        ADD TAG Pressure
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/pressure"
    
    ADD MAPPING SlowChangingData
        WITH EVERY 5 SECONDS
        ADD TAG ProductCount
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "INT32"
            WITH SOURCE_TOPIC "plc/production/count"

Combined (Cyclic + On-Demand)

A production route typically combines MAPPING for continuous monitoring with EVENT for on-demand operations. Publish a message to the EVENT’s SOURCE_TOPIC to trigger a one-shot read or write, and receive the result on the DESTINATION_TOPIC:

DEFINE ROUTE MyPLCConnection WITH TYPE <PROTOCOL_TYPE>
    ADD <PROTOCOL>_CONFIG
        WITH HOST "192.168.1.100"
        // Connection parameters...
    
    // Continuous monitoring — polls every 500ms
    ADD MAPPING ProcessSensors
        WITH EVERY 500 MILLISECONDS
        ADD TAG Temperature
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/temperature"
        ADD TAG Pressure
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/pressure"
    
    // On-demand read — triggered by publishing to SOURCE_TOPIC
    ADD EVENT ReadRegister
        WITH SOURCE_TOPIC "plc/commands/read"
        WITH DESTINATION_TOPIC "plc/responses/read"
        WITH QUERY "{operation: READ, address: <protocol_specific_address>, data_type: FLOAT}"
    
    // On-demand write — triggered by publishing to SOURCE_TOPIC
    ADD EVENT WriteSetpoint
        WITH SOURCE_TOPIC "plc/commands/write"
        WITH DESTINATION_TOPIC "plc/responses/write"
        WITH QUERY "{operation: WRITE, address: <protocol_specific_address>, value: 0}"

Advanced Example Pattern

When you need engineering-unit conversion, noise filtering, range validation, or bidirectional control, add transformation and publishing parameters to your TAGs. This pattern builds on the basic structure above to unlock the full power of industrial routes.

Scaled and Filtered Monitoring

Apply scaling and offset to convert raw PLC register values into meaningful engineering units, and use deadband to suppress noise:

DEFINE ROUTE AdvancedPLCConnection WITH TYPE <PROTOCOL_TYPE>
    ADD <PROTOCOL>_CONFIG
        WITH HOST "192.168.1.100"
        // Connection parameters...
    
    ADD MAPPING ProcessMonitoring
        WITH EVERY 500 MILLISECONDS
        ADD TAG Temperature
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/temperature"
            // Value transformation — raw 245 becomes (245 * 0.1) + (-40) = -15.5
            WITH SCALING 0.1
            WITH OFFSET -40
            WITH UNIT "°C"
            // Noise filtering — only publish when change exceeds 0.5
            WITH DEADBAND 0.5
            // Range validation — discard values outside physical limits
            WITH MIN_VALUE -20
            WITH MAX_VALUE 150
            // Precision — publish with 1 decimal place
            WITH DECIMAL_PLACES 1
            // Structured output — includes unit, description, and timestamp
            WITH PUBLISH_MODE "JSON"
        ADD TAG Pressure
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/sensors/pressure"
            WITH SCALING 0.01
            WITH UNIT "bar"
            WITH DEADBAND 0.1

Writable Setpoints with Validation

Enable bidirectional control by marking TAGs as writable. Published values on the DESTINATION_TOPIC are written to the PLC, with MIN/MAX enforcing safe limits:

    ADD MAPPING Setpoints
        WITH EVERY 1 SECOND
        ADD TAG TemperatureSetpoint
            WITH ADDRESS "<protocol_specific_address>"
            WITH DATA_TYPE "FLOAT"
            WITH SOURCE_TOPIC "plc/setpoints/temperature"
            // Bidirectional — publish to DESTINATION_TOPIC to write a value
            WITH WRITABLE "true"
            WITH DESTINATION_TOPIC "plc/setpoints/temperature/write"
            WITH UNIT "°C"
            // Safety limits — reject values outside the safe operating range
            WITH MIN_VALUE 0
            WITH MAX_VALUE 100

Best Practices

Optimize Polling Intervals

Group TAGs by update frequency:

Fast (50-100ms): Safety signals, real-time control
Medium (500ms-1s): Process values, sensor readings
Slow (5-30s): Configuration, counters, status

ADD MAPPING FastLoop
    WITH EVERY 100 MILLISECONDS
    // Critical TAGs only

ADD MAPPING SlowLoop
    WITH EVERY 5 SECONDS
    // Non-critical TAGs

Use Deadband for Analog Values

Reduce network traffic for slowly changing values:

ADD TAG Temperature
    WITH DEADBAND 0.5  // Only publish if change > 0.5

Apply Scaling at the Edge

Transform raw PLC values to engineering units in the route:

ADD TAG Temperature
    WITH SCALING 0.1   // Raw 245 becomes 24.5
    WITH OFFSET -40    // Apply offset if needed
    WITH UNIT "°C"

Use JSON Mode for Rich Data

Include metadata in published messages:

ADD TAG Temperature
    WITH PUBLISH_MODE "JSON"
    WITH UNIT "°C"
    WITH DESCRIPTION "Main reactor temperature"

Output:

{
  "value": 24.5,
  "unit": "°C",
  "description": "Main reactor temperature",
  "timestamp": "2024-01-15T10:30:00Z"
}

Secure Write Operations

Only enable WRITABLE for TAGs that need it, and use specific topics:

ADD TAG Setpoint
    WITH WRITABLE "true"
    WITH DESTINATION_TOPIC "plc/setpoints/temperature/write"
    WITH MIN_VALUE 0
    WITH MAX_VALUE 100

Next Steps

Choose the protocol that matches your equipment:

Modbus TCP

Start with the most common industrial protocol.

Siemens S7

Connect to Siemens PLCs directly.

Quick Start

Developing and Managing Coreflux

Coreflux MQTT Broker

LoT Language

Product Updates

Why Industrial Routes?

Industrial Protocol Integration

Supported Protocols

Modbus TCP

Modbus Serial

Siemens S7

OPC UA

ADS (Beckhoff)

Allen-Bradley

EtherNet/IP

FINS (Omron)

Protocol Comparison

Common Architecture

1. Connection Configuration

2. MAPPING with Polling

Common MAPPING-level fields

3. TAG Definitions

Common TAG Parameters

4. SOURCE_TOPIC Configuration

5. EVENT (On-Demand Operations)

Common EVENT Parameters

When to Use MAPPING vs EVENT

Basic Example Pattern

Cyclic Only

Combined (Cyclic + On-Demand)

Advanced Example Pattern

Scaled and Filtered Monitoring

Writable Setpoints with Validation

Best Practices

Next Steps

Modbus TCP

Siemens S7

​Why Industrial Routes?

​Industrial Protocol Integration

​Supported Protocols

Modbus TCP

Modbus Serial

Siemens S7

OPC UA

ADS (Beckhoff)

Allen-Bradley

EtherNet/IP

FINS (Omron)

​Protocol Comparison

​Common Architecture

​1. Connection Configuration

​2. MAPPING with Polling

​Common MAPPING-level fields

​3. TAG Definitions

​Common TAG Parameters

​4. SOURCE_TOPIC Configuration

​5. EVENT (On-Demand Operations)

​Common EVENT Parameters

​When to Use MAPPING vs EVENT

​Basic Example Pattern

​Cyclic Only

​Combined (Cyclic + On-Demand)

​Advanced Example Pattern

​Scaled and Filtered Monitoring

​Writable Setpoints with Validation

​Best Practices

​Next Steps

Modbus TCP

Siemens S7

Why Industrial Routes?

Industrial Protocol Integration

Supported Protocols

Protocol Comparison

Common Architecture

1. Connection Configuration

2. MAPPING with Polling

Common MAPPING-level fields

3. TAG Definitions

Common TAG Parameters

4. SOURCE_TOPIC Configuration

5. EVENT (On-Demand Operations)

Common EVENT Parameters

When to Use MAPPING vs EVENT

Basic Example Pattern

Cyclic Only

Combined (Cyclic + On-Demand)

Advanced Example Pattern

Scaled and Filtered Monitoring

Writable Setpoints with Validation

Best Practices

Next Steps