Publication 1747-UM655B-EN-P - June 2007
116 Data Map Example
Example Framework
This example adheres to the following structure:
• There cannot be any 1771-SDN modules or other 1747-SDN
modules on that network.
• DeviceNet devices may reside only at nodes 1…62.
• Address 0 must be used for the scanner.
• The first word in the device input data table contains the module
status word (this is applicable under any mapping scheme).
• Input data and status bits received from nodes 1…62 are
mapped to the scanner’s discrete-input data table.
The following illustrates an input-data mapping scheme example for
the 1747-SDN module. Input bits are mapped from a device’s
message, to the scanner’s input data table, and to the processor’s input
image table.
The status and data bits for each scanned device are mapped to the
scanner's discrete-input data table. Data bits are mapped in the first
four words while status bits are mapped in the next four words of the
table. The bit numbering for device data bits begins with 0. This
numbering starts over in word 5 for device status bits. This feature
makes it possible to directly correlate a device's MAC ID with the
placement of its bits in the data table. For example, the data bit for
node #11 is mapped to bit 11, word 1 in the data table. Its status bit is
mapped to bit 11, word 5 of the data table.
The processor reads the scanner's data table to transfer its contents to
the SLC-processor input image table.
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