Watlow Electric RUI/Gateway Guia do Utilizador descarregar pdf

RUI/Gateway & EtherNet/IP

Configuration & Ladder Logic Example

Using an Allen-Bradley CompactLogix PLC

Telephone: 507-494-5656 1 1/28

EtherNet/IP Fundamentals

EtherNet/IP is built on the Common Industrial Protocol (CIP) at a foundational level. When

communicating using CIP there are two ways to communicate to/from the Master and Slave

devices, i.e., Implicitly (real-time I/O messaging) and Explicitly (information/configuration

messaging). For your reference, the Watlow device is always the Slave where the PLC is the

Master on the network. This document will look closely at both methods of communication.

Explicit Communications - Defined

This type of messaging is executed on demand and can vary in size. Every message must be

individually configured to execute a specific Message Type, e.g., CIP Generic and a specific

Service Type, e.g., Get Attribute Single. Each device will interpret the message, act upon

the task and then generate a response. This message type encapsulates information about

the protocol itself as well as the instructions that need to be carried out in a TCP/IP packet.

When a message is sent using TCP/IP it requires a response from the device. As stated

above, this type of message is generally reserved for diagnostics and configuration.

Implicit Communications - Defined

Because implicit messaging is real-time I/O messaging, it places different demands on the

system. Due to the time critical nature of this form of communications the protocol must be

able to support multi-casting while also ensuring that the time to execute the task is as fast

as possible. To do this effectively, EtherNet/IP incorporates a protocol called User

Datagram Protocol/Internet Protocol (UDP). Basically, this protocol contains the data alone

without requiring a response from the Slave device. All data that is passed implicitly is

defined in the configuration or start up process. Because this method of communications

contains the predefined data alone, it is considered to be low overhead and is therefore able

to deliver the time-critical requirements for control.

By using both forms of communication EtherNet/IP can prioritize time-critical I/O

communications over non-critical messages while allowing for both to occur simultaneously.

Watlow EtherNet/IP equipped devices supports both forms (Explicit/Implicit) of

communications.

1.0 Getting Started

Prior to configuring the EZ-ZONE Remote User Interface (RUI) / Gateway (GTW) it is

important to think through the needs of the application while also understanding some basic

facts that pertain to the RUI/GTW.

Note: This document will not cover basic configuration of the RUI/GTW for this is covered in

the RUI/GTW User’s Guide which can be found on the Watlow website; link provided

below. http://www.watlow.com/literature/manuals.cfm

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