8-34 Serial Communications
1560D-UM051D-EN-P – February 2005
DeviceNet Examples (cont.) Explicit Messaging (cont.)
Size: This identifies the size of the transaction body in bytes. The
transaction body begins at word 3. The maximum size is 58 bytes. The
Size data size is one byte.
Service: This code specifies the type of request being delivered. The
Service data size is one byte.
Mac ID: The DeviceNet network node address of the device for which the
transaction is intended is identified here. The slave device must be listed in
the scanner module’s scan list and be on-line for the Explicit Message
transaction to be completed.
Class: The desired DeviceNet class is specified here. The Class data size
is one word.
Instance: This code identifies the specific instance within the object class
towards which the transaction is directed. The value zero is reserved to
denote that the transaction is directed towards the class itself versus a
specific instance within the class.
Attribute: This code identifies the specific characteristic of the object
towards which the transaction is directed. The Attribute data size is one
word.
Examples
The following table lists the most common codes for each given transaction
type:
Transaction Type Service
Class
Instance
Attribute
Single Parameter Read 0E 0F Par.#
1
Single Parameter Write 10 0F Par.#
1
Scattered Parameter Read 32 93 0 0
Scattered Parameter Write 34 93 0 0
The numerical values are in a hexidecimal format.
This is the actual parameter number as listed in Appendix B of this manual.
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