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1761-6.5
8-2
Explicit Messaging (DNI Series B Only)
The Series B DNI also has the ability to exchange data with other
DeviceNet devices using explicit messaging, provided those devices are
capable of interacting. Some of the requirements include:
•
If a device is Unconnected Message Manager (UCMM) capable, it
should be 100 percent compliant with or without a master being present
on the network.
•
If a device is not UCMM capable, it will need a master to be present on
the network, and it should be owned by the master.
•
If a device is not UCMM capable and a master is not present (or a master
is present but the device is not owned by the master), the device will not
be compatible with the DNI using explicit messaging.
Using DF1 Protocol for Explicit
Messages Over DeviceNet
The DNI is an intelligent bridge between DF1 Full Duplex (Allen-Bradley
open protocol) and DeviceNet. All Allen-Bradley controllers that use DF1
protocol (basically any Allen-Bradley controller with an RS-232 port) use
the historical source/destination model to move data.
The problem with this is that DeviceNet uses the newer producer/consumer
model and is not compatible with the source/destination model. So, to allow
controllers that use the source/destination model (MicroLogix, SLC, PLC)
access to devices on DeviceNet, the DNI can act as an intermediary.
To act as an intermediary, the DNI must allow the historical DF1 message
format to be compatible with the newer DeviceNet producer/consumer
object model. This is accomplished by creating a routing profile. The
routing profile basically takes the DF1 message and converts it to
DeviceNet. Each routing profile contains the information needed to get or
set data to other DeviceNet devices.
Each routing profile has five components:
•
Node - The address of the Device on DeviceNet
•
Class - The DeviceNet class code
•
Instance - The DeviceNet instance code
•
Attribute - The DeviceNet attribute code
•
Size - The amount of data to be read or written
The DNI can store up to 10 profiles. These profiles can be changed at any
time, and they are not backed up with a battery. If the power to the
DeviceNet network is lost, the profiles are cleared and must be reloaded.
This can be done with a subroutine.
Note:
A message instruction returning an error code of 0xD0H is an
indication that profiles need to be re-configured.
Содержание DeviceNet 1761-NET-DNI
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Страница 16: ...1761 6 5 1 2 Product Overview...
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Страница 74: ...1761 6 5 6 16 Setup Programming and T roubleshootin g...
Страница 84: ...1761 6 5 7 10 Application Examples...
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