Setting Up an RMC EtherNet/IP I/O Connection

This topic describes the concepts involved in setting up an EtherNet/IP I/O connection. For step-by-step procedures for Allen-Bradley PLCs, see Configuring an RMC EtherNet/IP I/O Connection for the ControlLogix. For details on controlling the RMC once a connection has been made, see Controlling the RMC over EtherNet/IP I/O.

Setting up an EtherNet/IP I/O connection involves the following concepts:

• Using the Correct EDS File

• Connection Type

• Requested Packet Interval (RPI)

• Multicast vs. Point-to-Point (Unicast)

• Using a Generic EDS File

Using the Correct EDS File

Many vendors’ EtherNet/IP configuration tools support importing the RMC’s EDS file and then use the contents of this file to correctly configure a number of internal settings. However, some configuration tools—most notably RSLogix 5000 as of this writing—do not use EDS files to configure EtherNet/IP I/O connections. For tools such as these, see the Using a Generic EDS section below, or for RSLogix 5000, see the Configuring an RMC EtherNet/IP I/O Connection for the ControlLogix topic.

There are two EDS files currently available for RMC100 Ethernet module. Current versions are available for download from Delta’s website www.deltamotion.com. Each EDS file is packaged in a compressed (.zip) file with its corresponding icon. Use the following table to select the correct EDS file to download:

1This revision refers to the EtherNet/IP Identity Object revision, not the firmware revision. This revision only changes when the EtherNet/IP functionality is changed.

Once the correct EDS compressed file has been downloaded, extract the EDS file and icon to a temporary folder and import them into your EtherNet/IP configuration tool.

Connection Type

The RMC supports two types of I/O connections:

• Input/Output
  This connection is bidirectional: the originator (PLC or HMI) produces data consumed by the RMC and the target (RMC) produces data that is consumed by the originator. This connection type is also called an Exclusive Owner connection or the controlling connection. Each RMC can have no more than one Input/Output connection open at a time.

• Input Only
  For this connection type, only the target (RMC) produces data, which is consumed by the originator (PLC or HMI). The originator will only send a heartbeat packet, sometimes at a reduced interval (less frequently than the RPI) used to allow the RMC to identify when the connection is broken.

Of these two, the Input/Output connection type is by far the most commonly used. The Input Only is generally only used when multiple I/O connections are used. See the Establishing Multiple I/O Connections with a Single RMC topic for details.

When using the RMC’s EDS file in your EtherNet/IP configuration tool, you should be able to select the I/O connection type from a list. If you are using a Generic EDS File (as required by RSLogix 5000 prior to version 20.00), see the Using a Generic EDS File section below.

Requested Packet Interval (RPI)

EtherNet/IP I/O sends data between the communicating devices at the Requested Packet Interval (RPI). The RPI is configured in the EtherNet/IP controller (for example, RSLogix 5000), not in RMCTools. The RMC supports the following RPIs, based on the number of simultaneous I/O connections established (see the Establishing Multiple I/O Connections with a Single RMC topic):

Delta recommends using the slowest RPI that meets the requirements of your application in order to reduce network requirements. See the EtherNet/IP Performance Overview topic for more details.

Multicast vs. Point-to-Point (Unicast)

The RMC supports both multicast and unicast (point-to-point) I/O connections. Traditionally, most EtherNet/IP I/O connections have been multicast, since Allen-Bradley controllers did not support unicast I/O connections until RSLogix 5000 version 18.00.00 was released in March 2010. However, multicast connections are much more demanding on the network bandwidth and require special switchgear (either routers or special switches with IGMP snooping/querying capabilities) to limit the spread of multicast traffic across the network. The RMC only requires multicast I/O connections when multiple I/O connections will be established at once, which is quite rare. Therefore, in almost all cases, unicast I/O connections should be selected whenever supported by the EtherNet/IP I/O controller.

Using a Generic EDS File

Some PLC EtherNet/IP configuration tools do not support importing third-party EDS files. In these cases, additional connection configuration information usually must be entered into a generic device template. The following chart provides the correct values for various connection settings that may be required by your EtherNet/IP configuration tool:

1 The term ‘Assembly Instance’ is used by some applications instead of ‘Connection Point’.

2 The Input and Output Connection Points and Config Data Assembly Instance are implied by the Connection Path. Therefore, configuration tools will generally either ask for the Connection Points and Instances or the Connection Path but not both.

3 This value is the common default value for this setting and the option to change this field may not be offered by the configuration tool.

4 The O->T size does not include the 2-byte transport header and, for Input/Output connections, the 4-byte Run/Idle header.

5 The T->O size does not include the 2-byte transport header.

Unfortunately, which fields are required and how they are presented varies significantly from one tool to the next. For this reason, most EtherNet/IP configuration tools are moving toward supporting importing EDS files to reduce the complexity of setting up an I/O connection.

The following chart shows the fields required to set up an EtherNet/IP generic device connection using Rockwell Automation’s RSLogix 5000. For step-by-step instructions on setting up an Input/Output connection using RSLogix 5000, see the Configuring an RMC EtherNet/IP I/O Connection for the ControlLogix topic.

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