EtherNet/IP Nodes

EtherNet/IP is the industrial Ethernet protocol used by Allen-Bradley PLCs (ControlLogix, CompactLogix, Micro820). MaestroHub provides two node types for EtherNet/IP integration: the standard EtherNet/IP Node for executing individual functions, and the EtherNet/IP Read Group Node for batch read operations.

EtherNet/IP Node

The EtherNet/IP node executes a single function from your EtherNet/IP connection. The function you select determines whether the node performs a read, write, browse, or batch operation.

Configuration

EtherNet/IP and Read Group Nodes

The node configuration has two tabs: Parameters and Settings.

Parameters Tab

Field	Description
Connection	Select the EtherNet/IP connection profile to use
Function	Choose a saved function from the connection (read, write, browse, or batch operation)
Function Parameters	Fill in any parameters defined in the function. Accepts literal values or Maestro expressions (e.g., $input, $.payload.id)
Timeout Override (seconds)	Optional. Override the default function timeout for this node

Settings Tab

Field	Description
Retry on Fail	Number of retry attempts if the function fails
On Error	How to handle errors: stop pipeline or continue to error branch
Notes	Operator notes for documentation
Display Note In Pipeline	Show notes directly on the canvas

Supported Function Types

Function Type	Purpose	Common Use Cases
Read Tag	Read a single tag value (scalar or array)	Temperature readings, motor status, setpoint verification
Write Tag	Write a single value to a tag	Update setpoint, change mode, trigger action
Read Multiple Tags	Batch read multiple tags in one operation	Dashboard updates, process snapshots, historian logging
Write Multiple Tags	Batch write to multiple tags	Recipe download, coordinated updates, batch configuration
Browse Tags	List all available tags with optional filtering	Tag discovery, documentation, setup validation

Output Examples

Read Tag Output:

{
  "value": 75.5,
  "tagName": "Temperature",
  "dataType": "real"
}

Write Tag Output:

{
  "tagName": "Setpoint",
  "success": true
}

Read Multiple Tags Output:

{
  "results": [
    { "tagName": "Temperature", "value": 75.5, "success": true },
    { "tagName": "Pressure", "value": 14.7, "success": true }
  ]
}

Write Multiple Tags Output:

{
  "results": [
    { "tagName": "Setpoint1", "success": true },
    { "tagName": "Setpoint2", "success": true }
  ]
}

Browse Tags Output:

{
  "tags": [
    { "name": "Temperature", "dataType": "real", "scope": "controller" },
    { "name": "Motor1_Speed", "dataType": "dint", "scope": "controller" },
    { "name": "Program:Main.LocalVar", "dataType": "int", "scope": "program" }
  ]
}

Safety First

Always implement validation and safety checks before writing to industrial equipment. Consider adding condition nodes to verify values are within safe ranges.

EtherNet/IP Read Group Node

The EtherNet/IP Read Group node is an advanced connector node that allows you to execute multiple EtherNet/IP read operations efficiently within a single node. It provides powerful grouping capabilities and the Read All feature for comprehensive data collection.

When to Use Read Group vs. Standard Node

Approach	Use Case
EtherNet/IP Node	Execute a single function (read, write, browse, or batch operation)
Read Group Node	Execute multiple read functions from one or more connections in a single node

Configuration

Connection and Functions

The Read Group node supports adding multiple function references, where each reference can either:

• Target a specific function from the connection
• Use Read All to execute all read functions associated with a connection

Read All Feature

The Read All toggle changes the behavior of a function reference:

Mode	Description	Use Case
Specific Function (default)	Execute a single named function	Selective data collection from specific tags
Read All	Execute all read functions from the connection	Complete PLC data snapshot, monitoring dashboards

How to Enable Read All

1. Add a function reference in the EtherNet/IP Read Group node
2. Toggle the Read All switch for that reference
3. Optionally provide a Group Key (defaults to connection ID if not specified)

When Read All is enabled:

• The function selector is hidden (not needed)
• All read functions (Read Tag, Read Multiple Tags) from the selected connection are executed
• Results are grouped under the specified group key or connection ID

Output Structure

{
  "connectionId_or_groupKey": {
    "function1_name": { /* function result */ },
    "function2_name": { /* function result */ },
    "function3_name": { /* function result */ }
  }
}

Parameters

Parameter	Description	Options
Execution Mode	How functions are executed	parallel (default), sequential
Continue on Error	Whether to continue if a function fails	true, false (default)
Functions	List of function references	Array of connection/function pairs

Execution Modes

Parallel Execution (Default)

• All functions execute concurrently
• Faster total execution time
• Best for independent read operations
• Use when accessing different tags

Sequential Execution

• Functions execute one after another
• More predictable timing
• Better for PLCs with limited concurrent request handling
• Use when PLC performance is a concern

Error Handling

Continue on Error = false (Default)

• Node fails if any function fails
• Ensures data consistency
• Best for critical operations where partial data is not acceptable

Continue on Error = true

• Node continues even if individual functions fail
• Failed functions return error in their result
• Best for monitoring scenarios where partial data is valuable
• Successful function results are still available in output

Best Practices

When to Use Read All

• Initial PLC commissioning and exploration
• Complete process data backups
• Dashboard views requiring all PLC data
• Diagnostic and troubleshooting scenarios

When to Use Specific Functions

• Production pipelines with known data requirements
• Performance-sensitive operations
• Selective data forwarding to specific systems
• When only a subset of PLC data is needed

Performance Considerations

• Read All executes all defined read functions, which may impact performance on large function sets
• Consider using parallel execution mode for Read All to optimize speed
• Monitor PLC capabilities - some PLCs may have limits on concurrent requests
• Use Continue on Error strategically based on data criticality

Naming Conventions

• Use descriptive Group Keys when using Read All with multiple connections
• Group Keys help organize output data in complex pipelines
• Default connection ID grouping works well for simple scenarios

Supported Data Types

EtherNet/IP nodes support all standard CIP data types:

Data Type	Description	Example Values
bool	Boolean	true, false
sint	Signed 8-bit integer	-128 to 127
int	Signed 16-bit integer	-32768 to 32767
dint	Signed 32-bit integer	-2147483648 to 2147483647
lint	Signed 64-bit integer	Full 64-bit range
usint	Unsigned 8-bit integer	0 to 255
uint	Unsigned 16-bit integer	0 to 65535
udint	Unsigned 32-bit integer	0 to 4294967295
ulint	Unsigned 64-bit integer	Full 64-bit range
real	32-bit float	75.5, -3.14159
lreal	64-bit float	High-precision decimals
string	Character string	"Hello World"

Tag Naming Reference

Tag Type	Format	Example
Controller-scoped	TagName	Temperature, Motor1_Speed
Program-scoped	Program:ProgramName.TagName	Program:Main.LocalVar
Array element	TagName[index]	DataArray[0], Temps[5]
Structure member	TagName.Member	Motor.Speed, Pump_Data.Pressure