Rockwell-automation 842D-60131331BXA DeviceNet Encoder User Manual Manual do Utilizador descarregar pdf (Página 27)

Chapter 5

Configuring a Scanner to

Communicate with the Encoder

Chapter Objectives Chapter 5 provides instructions for configuring a PLC or SLC scanner

to communicate with the encoder.

Required Equipment and

Software

Before configuring the scanner, your PC must be:

• Running RSNetWorx for DeviceNet. Refer to

http://www.software.rockwell.com for more information.

• Connected to and communicating with the DeviceNet network

using a DeviceNet interface such as a 1784-PCD card or a

1770-KFD adapter.

Operating Modes of the

Encoder

There are two fundamentally different DeviceNet protocols:

• Explicit messaging

• I/O messaging

Explicit messaging

Explicit messaging is used for modifying the device configurations,

reading diagnostic values, program upload / download, etc.

Characteristics of explicit messaging:

• Very flexible

• Less efficient because each device must interpret and generate a

response

• "Unbound" connections ("Hit and Run")

• Contents of the data field:

– Protocol information

– Instructions for service to be performed

– Internal address to which the service is to be applied

I/O messaging

I/O messaging is used for fast or time-critical data transfer. All of the

8 data bytes of the CAN telegram can be used for data transmission.

Characteristics of I/O messaging:

• Less flexible

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Rockwell-automation 842D-60131331BXA DeviceNet Encoder User Manual Manual do Utilizador Página 27