EtherNet/IP

EtherNet/IP is Rockwell Automation’s implementation of CIP (Common Industrial Protocol) over standard Ethernet/TCP-IP. It is used by Allen-Bradley/Rockwell PLCs and by other CIP devices that address data through symbolic tag names rather than fixed memory addresses.

This page covers the eip driver, which speaks generic CIP symbolic addressing. The same Java tag class also backs the logix driver code, registered by the same module - see Logix for that protocol’s page.

Supported Operations

Connection String

The EtherNet/IP connection string has the following format:

eip://{ip-address}:{port}?{options}

tcp is the only supported transport and is the default, so it is omitted from the connection string. The port defaults to 44818 and normally does not need to be given:

eip://192.168.24.32

Connection String Options

Name

Type

Default Value

Required

Description

Name

EthernetIP

Code

eip

Maven Dependency

<dependency>
  <groupId>org.apache.plc4x</groupId>
  <artifactId>plc4j-driver-eip</artifactId>
  <version>1.0.0</version>
</dependency>

Default Transport

tcp

Supported Transports

• tcp

Config options:

big-endian

BOOLEAN

true

Configure if the connection should be set to transport data in Big-Endian format, or not.

connection-serial-number

INT

0

Connection serial number to use in Forward_Open. CIP wants this unique per connection, so the default of 0 means 'pick a random one per connection'. Set it explicitly only when the exchange has to be reproducible, e.g. in recorded tests.
Since: 1.0.0

force-unconnected-operation

BOOLEAN

false

Forces the driver to use unconnected requests.
Since: 0.13.0

request-timeout-ms

INT

10000

Default timeout for all types of requests.

communication-path

STRING

The communication path allows for connection routing across multiple backplanes. It uses a common format found in Logix controllers.
It consists of pairs of values, each pair begins with either 1 (Backplane) or 2 (Ethernet), followed by a slot in the case of a backplane address, or if using Ethernet an ip address. e.g. [1,4,2,192.168.0.1,1,1] - Routes to the 4th slot in the first rack, which is an Ethernet module, it then connects to the address 192.168.0.1, then finds the module in slot 1.

Transport config options:

tcp

tcp.connect-timeout-ms

INT

5000

Connection timeout in milliseconds.

tcp.read-timeout-ms

INT

0

Socket read timeout in milliseconds. 0 means no timeout.

tcp.write-timeout-ms

INT

0

Socket write timeout in milliseconds. 0 means no timeout.

tcp.no-delay

BOOLEAN

true

Enable TCP_NODELAY (disable Nagle’s algorithm).

tcp.keep-alive

BOOLEAN

false

Enable SO_KEEPALIVE.

tcp.send-buffer-size

INT

81920

Send buffer size in bytes. 0 uses system default.

tcp.receive-buffer-size

INT

81920

Receive buffer size in bytes. 0 uses system default.

tcp.local-address

STRING

Local address to bind to (optional). If not set, uses default.

tcp.local-port

INT

0

Local port to bind to (optional). 0 uses ephemeral port.

Tag Addresses

Addressing is implemented in Go and Java. See the protocol support matrix for what each implementation does.

General Format

To read and write data to a PLC4X device, the EtherNet/IP driver uses symbolic segments. This is used to refer to objects through their symbolic names. This makes reading data a lot easier, as you do not need to specify the Datatype for reading.

{tagname}
{tagname}:{DataType}
{tagname}[{selection}]
{tagname}[{selection}]:{DataType}

Data Types

These are the data types the driver can encode and decode:

Examples

Table 1. Examples