Serial Communications 8-33
1560D-UM051D-EN-P – February 2005
Explicit Messaging
The 1747-SDN scanner module uses the M0 and M1 file areas for data
transfer. Words 224 through 256 must be used to execute the Explicit
Message Request and Response functions. The minimum data size for an
Explicit Message Request is 6 words and the maximum is 32 words.
Following is the data format to follow for a scattered parameter value read
(Get Attribute Multiple) as used in this example:
Explicit Message Request (Get Attribute Multiple)
15 0 Word 0
TXID COMMAND
PORT SIZE
SERVICE MAC ID
CLASS
INSTANCE
ATTRIBUTE
PARAMETER
PATA PLACE HOLDER
“ Word 31
Explicit Message Response (Get Attribute Multiple)
15 0 Word 0
TXID STATUS
PORT SIZE
SERVICE MAC ID
PARAMETER
DATA
“ Word 31
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.
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