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Protocol_EtherNetIP-Master

Protocol_EtherNetIP-Master

Oct 06, 2023

Table of Contents

 

Introduction

The RediGate Configuration Manual describes the configuration of many of the RediGate's standard features using the ACE program. This document gives additional instructions for configuring the RediGate to use the following protocol:

  • Rockwell Automation/Allen Bradley EtherNet/IP (EIP/CIP) Master

 

The EtherNet/IP master will communicate with ControlLogix, CompactLogix, and MicroLogix-820 PLCs. See the following Quick Start example configuration:

To communicate with PLC5, SLC50x, or MicroLogix-1xxx PLCs, you will need to use the DF1 protocol instead.

 

 

EtherNet/IP Protocol Description

This document is not intended to provide a detailed description of the protocol(s) involved, nor to disclose proprietary information that may belong to other parties. Depending on the protocol, it may be necessary to refer to other vendor protocol documentation or device configuration details to understand how the RediGate should be configured to interface with it. This section provides a brief discussion of the protocol for the purpose of understanding the RediGate's configuration objects.

The Ethernet/IP protocol (EIP/CIP, an adaptation of Common Industrial Protocol, managed by ODVA) uses an object-oriented data model and employs both TCP/IP and UDP/IP as the transport protocols. An EtherNet/IP-compliant PLC or device will be configured with CIP objects having data that is typically defined in structures that may contain a mix of different data types and are typically identified by tag names. This differs from many other protocols supported by the RediGate, which commonly use a register-based data format. The RediGate's Poll Table is able to read CIP objects from the PLC and parse them into Real-time Database (RTDB) registers using the appropriate data types.

This document does not describe configuration of Allen Bradley DF1 or CSP protocols. The RediGate does not currently support Data Highway Plus (DH+), which requires a special hardware interface.

 

The following sections describe the ACE objects used for DF1 and CSP Master, object properties (including constraints on the Instance number), and object fields and their possible values required to configure for the given protocol(s). The object structure in ACE is hierarchical, with each object existing under a certain parent object. For instance, the FieldUnit is the child of one of several types of Circuit objects, either serial or network type (" System>Clients>Master Channels>Master Channel>Circuit").

The Description and Enabled properties are included in ACE as part of each object but are not mentioned here. The "UFF External" property is only mentioned for the objects where it is typically used, but should normally be left unchecked.

Supported Features and Limitations of EtherNet/IP Master

CIP objects may contain complex arrays and nested structures of data organization. In order to simplify the process of creating RediGate configurations, Elecsys provides a tool for converting the PLC configuration file (L5X) into the tables necessary for configuring the Scan Table, Poll Table, RTDB, and TagName tables.

The RediGate supports many standard features of EtherNet/IP, including:

Supported Data Types

RediGate can read the following Atomic data types: Bit, Int-8, Int-16, Int-32, Int-64, Real-32. A String is considered a structure.

RediGate can read the following Pre-defined Data Types (PDTs) of: TIMER, COUNTER, CONTROL, ALARM_ANALOG, ALARM_DIGITAL, PID, and STRING.

RediGate can read and write single data elements, arrays (single-dimensional only), UDT/PDT structures (up to 4000 bytes), array of Atomic elements within a structure, or a single structure within a structure (one level deep only).

UNsupported Data Types

RediGate currently cannot read PDTs that include ENCODED_DATA, MESSAGE, MODULE, ROUTINE, CONNECTION, PROGRAM, MOTION_GROUP, MOTION_INSTRUCTION, and AXIS.)

RediGate does not support structures within structures more than one level deep, and does not support an array of structures inside a structure.

  • Top-level arrays of structures will be read with one structure per poll. Groups of Atomic tags are scanned ten per transaction.
    For example, a simple array of 10 timers, TimerArray[10], will execute ten separate polls of TimerArray[0] to TimerArray[9].

  • When reading large arrays, they will be broken into multiple blocks of 460 bytes.

  • Item tag names are imported from the L5X file. RediGate does not support automatic discovery of tags.

  • Data writes to Bit arrays are done by first reading 32 Boolean values from the RTDB, masking in the new values, and then writing all 32 Booleans to the PLC's 32-bit word.

Following are some additional limitations of the EtherNet/IP Master in the RediGate:

  • If elements are added or removed from a UDT structure, you should go through the L5X Import Tool to re-import the four tables into ACE (Scan Table, Poll Table, RTDB, TagNames, rather than modifying the tables by hand.

  • Implicit messaging (unsolicited data from device using RPI cycle time) via UDP is not supported.

  • Only peer-to-peer, single-level communications are allowed. No tunneling is allowed through PLCs to other PLCs, networks, or protocols using the EtherNet/IP master driver.

  • The EtherNet/IP Master is unable to identify "Local:1" physical I/O items. The PLC program must create tags or aliases for each I/O point required in the polling communication.

If an external Modbus host is reading PLC data from the RediGate using a Modbus Slave Channel, then there are special requirements for the organization of RTDB registers (see the "Modbus Slave Attach" section of the RediGate Configuration Manual). 

Using the L5X Tool

See the Ethernet/IP Master Quick Start documentation for instructions on setting up a demo configuration to poll an EtherNet/IP device.

See Using the L5K Import Tool for brief instructions on using the ACE Configuration Management Utility to select PLC tags.

Or see ACE Configuration Management (ACM) Utility for more detailed instructions on using the ACM utility.

 

EtherNet/IP Master Channel

The structure of ACE objects for a Master Channel used for the EtherNet/IP protocol is shown below:

EtherNet/IP Master

Note the following when configuring the Master Channel for EtherNet/IP devices:

  • Response Timeout needs to be set greater than the Scan Period - this is because the RediGate uses the Response Timeout to notify the EtherNet/IP PLC of what period it should expect to be polled (or else the PLC may shut down its open socket prematurely).

  • The Scan Table should be imported using the L5X Import tool in the ACM Utility. The PLC polling setup can get somewhat complicated, so it is not recommended to modify the table by hand.

  • If the configuration includes more than one EtherNet/IP device, either configure them under different Master Channels, or under separate Network Circuits.

Network Circuit


A Network Circuit is an IP network communications path to one or more field units from a common Master Channel. The Network Circuit is used when the field unit is connected to the RediGate over a TCP/IP network.

To configure the Network Circuit for an EtherNet/IP PLC:

  • Use Master Network Port = 44818.

  • Set the Circuit Type to be "Network Circuit."

  • Set the Connect Table to the IP address of the PLC.