National-instruments NI-DNET Manual de usuario descargar pdf (Pagina 15)

Chapter 1 NI-DNET Software Overview

NI-DNET User Manual 1-6 ni.com

• Execute the DeviceNet Set Attribute Single service on the remote

device (

ncSetDnetAttribute)

• Send any other explicit message request to the remote device and

receive the associated explicit message response

(

ncWriteDnetExplMsg, ncReadDnetExplMsg)

• Configure NI-DNET settings that apply to the entire remote device

I/O Object

The I/O Object represents an I/O connection to a remote DeviceNet device

(physical device attached to your interface by a DeviceNet cable). The

I/O Object usually represents I/O communication as a master with a remote

slave device, but it can also be used for I/O communication as a slave.

The I/O Object supports as many master/slave I/O connections as currently

allowed by the DeviceNet Specification. This means that you can use

polled, strobed, and COS/cyclic I/O connections simultaneously for a given

device. As specified by the DeviceNet Specification, only one master/slave

I/O connection of a given type can be used for each device (MAC ID). For

example, you cannot open two polled I/O connections for the same device.

Use the I/O Object to do the following:

• Read data from the most recent message received on the

I/O connection (

ncReadDnetIO)

• Write data for the next message produced on the I/O connection

(

ncWriteDnetIO)

Example

Figure 1-2 shows an example of how NI-DNET objects can be used to

communicate on a DeviceNet network. This example shows three

DeviceNet devices. The first device (at MAC ID 1) is the National

Instruments DeviceNet interface. The second device (at MAC ID 5) uses

NI-DNET to access a polled and a COS I/O connection simultaneously.

The third device (at MAC ID 8) uses NI-DNET to access an explicit

messaging connection and a strobed I/O connection.

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National-instruments NI-DNET Manual de usuario Pagina 15