EtherNet/IP Overview

EtherNet/IP is an open application protocol, maintained and distributed by ODVA (https://www.odva.org). EtherNet/IP is used by Ethernet modules for several PLC's including Allen Bradley, Schneider Electric, and Omron. EtherNet/IP is an Ethernet adaptation of the Control Information Protocol (CIP) in the same way that DeviceNet is a CAN adaptation of CIP and ControlNet is a CTDMA adaptation of CIP.

The RMC is a passive EtherNet/IP device. It does not establish its own I/O connections, nor does it initiate messaging transactions. Therefore, an active EtherNet/IP device or client is required to control the RMC or request data from the RMC.

The RMC statements of conformance and EDS files are available for download from the Delta website at https://deltamotion.com.

The RMC75E, RMC150E, and RMC200 support EtherNet/IP Messaging and EtherNet/IP I/O.

EtherNet/IP I/O

EtherNet/IP I/O provides a mechanism of deterministically sending data in both directions between a PLC and remote device. This data is sent on an interval called the Requested Packet Interval (RPI). EtherNet/IP I/O is a very fast and easy-to-use method of communication. It reduces the amount of ladder logic required for communication, and communication occurs even when the PLC is in Program mode.

Ethernet Protocol Mode Selecting PROFINET Protocol Mode (RMC200 Only)

In order to communicate via EtherNet/IP I/O, the RMC200 must be set to EtherNet/IP Mode:

In the Project pane, expand the RMC, and double-click the CPU.
On the Ethernet page, in the Ethernet Protocol Mode section, click EtherNet/IP Mode, then click OK.

The Ethernet Protocol Mode may also be viewed from the RMC200 Display Screen.

I/O Connections and Data

Connection Type	RMC75E	RMC150E	RMC200
Max Number of Input/Output Connections	1	1	3
Total Number of Connections, including Listen Only and Input Only	4	4	4
Connection#1 Size	125 input registers 124 output registers	125 input registers 124 output registers	360 input registers 360 output registers
Connection#2 Size	n/a	n/a	125 input registers 124 output registers
Connection#3 Size	n/a	n/a	125 input registers 124 output registers

The RMC also supports Input Only and Listening connections, as described in Setting up an EtherNet/IP I/O Connection.

The RMC supports only one type of controlling I/O connection at a time. Therefore, EtherNet/IP I/O cannot be used simultaneously with a PROFINET IO connection. Other protocols can be used simultaneously with EtherNet/IP.

To learn about setting up and using EtherNet/IP I/O, see the following topics:

Supported RPI (Requested Packet Interval)

	RMC75E	RMC150E	RMC200 CPU20L	RMC200 CPU40
Minimum RPI*	2 ms	2 ms	1 ms**	1ms
Typical RPI	20 ms
Maximum RPI	10000 ms

* The RPI may not be less than the loop time to which the RMC is set, and must be a multiple of the loop time.

** Not all CPU20L connections can be 1 ms. The CPU20L supports a bandwidth of 6000 packets per second and the CPU40 supports 8000 packets per second. The bandwidth of each connection is calculated as ( 2 / RPI ). For example, an RPI of 1 ms is 2/0.001 = 2000 packet/sec. The CPU20L can support 3 connections at 1 ms RPI.

EtherNet/IP Messaging

EtherNet/IP explicit messaging allows the originator (PLC or HMI) to request individual services from the target device (RMC). These requests are made explicitly rather than being scheduled cyclically like I/O. Explicit messaging is much more flexible than I/O in terms of what data or services are accessed in the target device, since I/O connections must pre-configure the I/O data to be exchanged.

In most cases, RMC users use EtherNet/IP Explicit messaging to read and write registers in the RMC. Also, some advanced EtherNet/IP users may want to access standard CIP services and attributes.

The three types of EtherNet/IP explicit messaging services users may want to use in the RMC are:

Read and/or write RMC registers using the Allen-Bradley PCCC/DF1 services.
Read and/or write RMC registers using the Register Map Object.
Access standard CIP services and attributes.

See Using EtherNet/IP Explicit Messaging for details on all three.

Supported Number of Connections

The maximum number of each type of connection supported by the RMCs is listed below:

Connection Type	RMC75E	RMC150E	RMC200
TCP	64	64	64
CIP (total of messaging and I/O)	32	32	20
CIP Messaging	up to 32	up to 32	16
CIP I/O	4 (1 with output data from the PLC)	4 (1 with output data from the PLC)	4 (up to 3 with output data from the PLC)