EtherNet/IP (Logix) Driver

Overview

EtherNet/IP based on CIP (Common Industrial Protocol). Primarily used to communicate with Allen-Bradley / Rockwell ControlLogix / CompactLogix PLCs.

Item	Value
`opc_type`	`EIP`
Implementation class	`plantpulse.driver.protocol.eip.EIP_34_Driver`
Library	digitalpetri/ethernet-ip (`CipClient` + `GetAttributeListService`)
read	✅ (attribute list raw bytes → String)
write	✅ (CIP Write Tag `0x4D` — scalars and arrays)
Security	None

Differences from PLC4j

Unlike the other PLC drivers, this one uses digitalpetri/ethernet-ip directly instead of PLC4j (it extends BaseProtocolDriver, not PLC4jProtocolDriver). PLC4j's plc4j-driver-eip is also present in lib, but this class does not use it.

OPC Registration Form

Field	Meaning	Example
`opc_agent_ip`	PLC IP	`192.168.0.90`
`opc_agent_port`	EIP port	`44818`
`timecycle`	Polling interval (ms)	`1000`
`options.backplane`	Backplane number	`1` (default)
`options.local-slot`	CPU slot number	`0` (default)

The internal timeout is fixed at 2 seconds (Duration.ofSeconds(2)).

Tag `plc_address` Format

EIP raw reads operate on CIP class / instance / attribute coordinates. In Edge, enter them in the plc_address field using the <class>,<instance>,<attribute> format (decimal or hexadecimal).

Notation	Meaning
`0x6B,1,1`	Symbol class 0x6B, instance 1, attribute 1
`0x6C,1,1`	Template class
`0x01,1,7`	Product Name of the Identity object

Symbolic tags (Tag1.Member)

Symbolic tag reads common in Logix (MyController:Tag1) require a separate service (Read Tag Service); this driver uses raw GetAttributeListService only. If symbolic reads are required, switch to the PLC4j EIP driver or implement the feature later.

`data_type` / `format` Mapping

`data_type`	`format`	Notes
String	(empty)	Response raw bytes are accumulated as a String as-is
Integer / Float / …	(empty)	Cast during post-processing. The current driver returns raw bytes → String

Casting to data_type is done in post-processing (PLCValueFomula / Sparkplug DataTypeMapper).

Common Errors and Fixes

Message / Symptom	Cause	Fix
Connection timeout	Port 44818 blocked, EIP not running	Enable the EtherNet/IP module in RSLogix / Studio5000
Forward Open failure	rack/slot mismatch	Correct `options.backplane` / `options.local-slot`
`Class/Instance not found`	Wrong class / instance ID	Verify the response with the Studio5000 Tag Browser or wireshark
Values look corrupted	Bytes converted to String as-is	Apply a formula in post-processing that interprets the data as 4-byte little-endian

curl Registration Example

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_EIP_LOGIX",
    "opc_type": "EIP",
    "opc_name": "Logix L83E",
    "opc_agent_ip": "192.168.0.90",
    "opc_agent_port": "44818",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": {
      "backplane": "1",
      "local-slot": "0"
    },
    "tag_list": [
      {
        "tag_id": "OPC_EIP_LOGIX_TAG_00001",
        "tag_name": "ProductName",
        "plc_address": "0x01,1,7",
        "data_type": "String"
      }
    ]
  }'

Example Collection (by Data Type)

An EIP raw read accumulates the raw bytes at the <class>,<instance>,<attribute> coordinate (decimal or 0x-prefixed hexadecimal) as a String. Casting to data_type / fomula is done in post-processing.

CIP Coordinate Format

`plc_address`	Meaning
`0x01,1,1`	Identity → Vendor ID
`0x01,1,2`	Identity → Device Type
`0x01,1,7`	Identity → Product Name (String)
`0x6B,1,1`	Symbol Class (Logix tag list) instance 1 attribute 1
`0x6C,1,1`	Template Class
`0x6C,2,1`	Template Class instance 2
`0x73,1,1`	Connection Manager

Mapping by Data Type

`data_type`	`format`	`plc_address` example	Notes
`String`	(empty)	`0x01,1,7`	Product name (raw bytes as String)
`Integer`	(empty)	`0x01,1,1`	Vendor ID. raw bytes → interpreted as little-endian via formula
`Integer`	(empty)	`0x01,1,2`	Device Type
`Boolean`	(empty)	`0x01,1,8`	Status word (bit extraction in post-processing)
`Float`	(empty)	`<class>,<inst>,<attr>`	4-byte raw response → post-processing

Current driver limitations

EIP_34_Driver calls only GetAttributeListService. If reading symbolic tags (MyController:Tag1.Member) is required, a separate implementation using the ControlLogix Read Tag Service is needed. PLC4j EIP is included in lib, so a later switch is possible.

Using Formulas

Purpose	`data_type`	`fomula`	Notes
Integer raw correction	`Integer`	`${VALUE}*1`	Pass-through without conversion
Combining two 16-bit values	`Integer`	`${TAG_HI}*65536+${VALUE}`	Combines the hi/lo attributes
Unit conversion	`Float`	`${VALUE}*0.1`	Scales the raw integer

Complete curl Example

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_EIP_FULL",
    "opc_type": "EIP",
    "opc_name": "Logix Full",
    "opc_agent_ip": "192.168.0.90",
    "opc_agent_port": "44818",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": { "backplane": "1", "local-slot": "0" },
    "tag_list": [
      {"tag_id":"OPC_EIP_FULL_T01", "tag_name":"VendorId",   "plc_address":"0x01,1,1", "data_type":"Integer"},
      {"tag_id":"OPC_EIP_FULL_T02", "tag_name":"DeviceType", "plc_address":"0x01,1,2", "data_type":"Integer"},
      {"tag_id":"OPC_EIP_FULL_T03", "tag_name":"ProductName","plc_address":"0x01,1,7", "data_type":"String"},
      {"tag_id":"OPC_EIP_FULL_T04", "tag_name":"Status",     "plc_address":"0x01,1,5", "data_type":"Integer"}
    ]
  }'

Overview​

OPC Registration Form​

Tag plc_address Format​

data_type / format Mapping​

Common Errors and Fixes​

curl Registration Example​

Example Collection (by Data Type)​

CIP Coordinate Format​

Mapping by Data Type​

Using Formulas​

Complete curl Example​