L100DN Inverter
61
Step 8 – Use DeviceNet Explicit Messaging
The control sequences in Step 7 showed how the network host computer can control the
inverter via polled I/O. While polled I/O data is continuously supplied (on each network
scan), it contains only a small set of control bits and values for the main running profile.
In addition, the inverter provides a direct way host computer to access individual inverter
parameters. In DeviceNet terminology, it is called
explicit messaging
.
The DeviceNet standards provide for a way to address individual devices on the network
(
nodes
), and data (
attributes
) within each device. A complete address consists of four
numbers: the Node Address (MAC ID), the Object Class Identifier, the Instance Number,
and the Attribute Number. An explicit message connection between two devices uses
these four numbers to identify and transfer data on a DeviceNet network. The four
address components and their ranges are shown in the following table:
A particular inverter on the network has a specific node address (default = 63). To access
a particular parameter in that inverter, the host computer uses the class, instance, and
attribute numbers together. The address ranges indicated in the table above could access
any one of thousands of values within a device, if needed. In DeviceNet terminology, a
read
access is called
get
, and a
write
access is called a
set
.
The assignment of DeviceNet explicit messaging addresses to inverters is somewhat
arbitrary. In this step we consider an example parameter, but the complete set for the
L100DN Series inverter is listed in the “Network Register Map” on page 78. The table
excerpt below shows parameter F_01 and its network address for explicit messaging.
When you construct a
get attribute
or
set attribute
request, refer to the Class ID in the
table title bar (100), and the Inst, Attr, and Size columns (1, 159, 2).
Address
Component
Lowest
Highest
Node
0
63
Class
1
65535
Instance
0
65535
Attribute
1
255
“F” Group Parameters, Example
DeviceNet Class ID = 100
Func.
Code
Name
Inst Attr Size
Range
Scaling
Get/
Set
F_01
Output frequency setting
1
159
2
0 – 360Hz
100
Get
Содержание L100DN DeviceNet Series Addendum
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