ICC
13.2 EtherNet/IP
13.2.1 Overview
The EtherNet/IP protocol is an application-level protocol implemented on top of the Ethernet TCP/IP and UDP/IP layers. It shares its object model with ControlNet and DeviceNet through the Common Industrial Protocol (CIP). This protocol allows the transfer of data and I/O over Ethernet.
EtherNet/IP incorporates both the TCP and UDP layers of Ethernet in the transmission of data. Because TCP/IP is a point-to-point topology, EtherNet/IP uses this layer only for explicit messaging; i.e. those messages in which the data field carries both protocol information and instructions for service performance. With explicit messaging, nodes must interpret each message, execute the requested task and generate responses. These types of messages can be used to transmit configuration, control and monitor data.
The UDP/IP protocol layer, which has the ability to multi-cast, is used for implicit (I/O) messaging. With I/O messaging, the data field contains only real-time I/O data; no protocol information is sent because the meaning of the data is pre-defined at the time the connection is established, which in turn minimizes the processing time of the node during run-time. I/O messages are short and have low overhead, which allows for the time-critical performance needed by controllers.
The interface card supports both explicit and I/O messaging. Further, two different types of I/O messaging are supported. One type (invoked when the client opens a connection to the interface using assembly instances 20 & 70 or 21 & 71) is included with the implementation of the AC/DC drive profile, and requires no user configuration. The other type, however, is entirely user-configurable, and is invoked when the client opens a connection to the interface using assembly instances 100 and 150.
The following sections demonstrate specific examples of how to use EtherNet/IP to transfer data between the drive and Allen-Bradley Logix-brand PLCs.
Some other notes of interest are:
•The interface card supports the EtherNet/IP protocol (release 1.0), administered by the Open DeviceNet Vendor Association (ODVA).
•This product has been self-tested by ICC, Inc. and found to comply with ODVA EtherNet/IP Conformance Test Software Version A-5.
•I/O connection sizes for assembly instances 100 and 150 are adjustable between 0 and 64 bytes (32 registers max @ 2 bytes per register = 64 bytes). Because registers are 16-bit elements, however, connection sizes cannot be odd (i.e. 1, 3, 5 etc.)
•The interface card’s product type code is 2 (AC drive.)
•Supports unconnected messages (UCMM), and up to 16 simultaneous class 1 (I/O) or class 3 (explicit) connections.
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