EtherNet/IP
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EtherNet/IP is a native driver for Allen-Bradley and Rockwell Automation PLCs. It communicates directly with the PLC’s tag database using CIP (Common Industrial Protocol) over standard Ethernet — no OPC server or middleware required.
Supported controllers
- ControlLogix
- CompactLogix
- MicroLogix
- Micro800 family (use the EtherNet/IP Micro800 connection type)
CompactLogix:
MicroLogix:
Connection parameters
| Parameter | Description |
|---|---|
| IP Address | IP address of the PLC |
| Slot | Backplane slot of the processor module — default 0 for most ControlLogix and CompactLogix setups |
| Refresh rate | Tag polling interval in milliseconds — default 500 ms |
Supported data types
| Data type | Description |
|---|---|
| BOOL | Single bit — true/false |
| SINT | 8-bit signed integer (−128 to +127) |
| USINT | 8-bit unsigned integer (0 to 255) |
| INT | 16-bit signed integer (−32 768 to +32 767) |
| UINT | 16-bit unsigned integer (0 to 65 535) |
| DINT | 32-bit signed integer (−2 147 483 648 to +2 147 483 647) |
| UDINT | 32-bit unsigned integer (0 to 4 294 967 295) |
| LINT | 64-bit signed integer |
| REAL | 32-bit IEEE floating-point |
| LREAL | 64-bit floating-point |
| BIT_STRING | Collection of bits, each accessible individually |
| UDT | User-defined data structure |
The data type is determined automatically during the first read from the PLC — it is not entered manually.
Tag addressing
Controller tags — enter the tag name directly:
Pressure
Temperature
ConveyorSpeedProgram tags — prefix with the program name:
Program:Control.Valve
Program:Line1.MotorRunningBOOL arrays (ControlLogix)
BOOL arrays in ControlLogix are addressed by word and bit position. Each word contains 32 bits:
| Element | Address |
|---|---|
| 3rd element | TestBool[0].3 |
| 34th element | TestBool[1].2 |
| 54th element | TestBool[1].22 |
Tag import
Online import — when the PLC is online, its tag list can be imported directly. The PLC must be online during import.
L5X file import — export your PLC project from Rockwell Studio as an .L5X file (including UDTs and alarm limits) and import it into DataTalk when creating the connection. This imports all tags and automatically creates alarm limits defined in the project.
After importing an L5X file, you can only select tags from the imported list — manual tag entry is disabled. If the PLC project changes, re-import the updated L5X file.
Communication speed
ControlLogix reads arrays significantly faster than individual elements. Organize tags in arrays when possible:
Fast — reading 10 tank levels as an array:
Level[1], Level[2], Level[3], ...Slow — reading the same data as structure members:
BigTank[1].Level, BigTank[2].Level, ...For Micro820, Micro830, Micro850, and Micro870 controllers, use the EtherNet/IP (Micro800) connection type instead of the standard EtherNet/IP adapter.