Rockwell Automation 284 ArmorStart User Manual - Manual (Page 255)

Explicit Messaging on DeviceNet™ 9-3
Table 9.5 Explicit Message Response (Get_Attribute_Single)
• 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. Please note that the 1747-SDN
has only one channel, and so this value is always set to zero.
• 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.
Bit location within Word
15 … 8 7 … 0
TXID STATUS Word - 0
PORT SIZE Word - 1
SERVICE MAC ID Word - 2
DATA Word - 3