Rockwell Automation 150 USE MN/SMC DIALOG + CONTROLLER - Manual (Page 139)

8-30 Serial Communications
Explicit Message Response (Get Attribute Multiple)
Transmission ID (TXID): The scanner uses this value to track the
transaction to completion, and returns the value with the response that
matches the request downloaded by the SLC-500 processor. The
TXID data size is one byte.
Command: This code instructs the scanner how to administer the
request. A listing of these codes can be found in the 1747-SDN User
Manual, Publication 1747-5.8. The Command data size is one byte.
Status: The Status code provides the communication module’s status
and its response.
Port: The physical channel of the scanner where the transaction is to
be routed. The port setting can be zero (channel A) or one (channel
B). The Port data size is one byte.
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.
15 0
TXID STATUS word 0
PORT SIZE
SERVICE MAC ID
PARAMETER
DATA
“ word 31