Rockwell Automation 1747-SDN SLC 500 DeviceNet Scanner Module User Manual - Manual (Page 115)

115 Publication 1747-UM655B-EN-P - June 2007
Appendix
A
Data Map Example
What This Appendix
Contains This appendix illustrates a basic mapping example that connects a
DeviceNet network to 62 simple sensor-type devices. Each device
sends one data byte that contains one data bit and one status bit.
These are given in response to a strobe message.
Example Input Mapping
Scheme This example’s input mapping scheme is a simplified and fixed map
of discrete input data and status bits for DeviceNet devices. It is
mapped to discrete inputs and the device input data table.
Example Characteristics
This example has the following characteristics:
•
Strobe is used to query DeviceNet devices.
•
Poll is disabled.
•
The input data bit is fixed and occupies the lowest-order bit in
the lowest-order byte of the strobe (bit #1).
•
One bit of status data is accepted from each node responding to
the strobe.
•
The status data bit is fixed and occupies the next lowest-order
bit in the next lowest-order byte (after the input data bit) of the
strobe (bit #2).
•
Input and status data bits accepted from each node are mapped
to the scanner’s discrete-input data table.
•
Input and status data bits accepted from each node are fixed and
predefined.
Topic Page
Example Input Mapping Scheme 115
Example Output Mapping Scheme 118