Chapter 6
6-3
Message Communications
■
Overview of Explicit Messages
Explicit messages are sent and received as described below. Basically explicit message communi-
cations are executed in 1-byte (8-bit) units.
Explicit Message Communications Frame
Header
Node
address
Service
code
Class
Instance
Attribute
Data
Footer
Item
Content
Header
The header indicates the beginning of an explicit message and that the frame is an
explicit message request/response. It is set automatically for DeviceNet, so there is no
particular need to be concerned with it.
Node address
Request: Set the node address of the Slave/Master to be requested.
Response: The node address of the responding Slave/Master is set.
Service code
Request: Set the code of the requested service (read/write, etc.).
Response: The MSB (most significant bit) of the requested service code is changed to
“1” and returned.
Class
Function classification (major
classification)
Indicates the classification of a function defined by
DeviceNet. To specify a function, specify these three
codes.
Instance
Instance classification (minor
classification)
Attribute
Attribute (Set values are
assigned for each function.)
Data
Request:
Set the data to be written.
Response: Read-requested data or fault message are attached.
Footer
This is the part that indicates the end of the explicit message and executes the CRC
check. It is set automatically for DeviceNet, so there is no particular need to be con-
cerned with it.
Summary of Contents for 3G3MV-PDRT2
Page 4: ......
Page 12: ......
Page 36: ...Chapter 1 1 22 Functions and System Configuration...
Page 52: ...Chapter 2 2 16 Example System Startup...
Page 94: ...Chapter 4 4 14 SYSDRIVE Inverter Settings...
Page 130: ...Chapter 5 5 36 Remote I O Functions...
Page 234: ...Chapter 8 8 14 Communications Errors...
Page 362: ...R 2 Revision History...