Rockwell Automation 1769-SDN Compact I/O DeviceNet Scanner Module User Manual - Manual (Page 37)

Publication 1769-UM009E-EN-P - August 2009 37
Automatically Configure a DeviceNet Network Chapter 4
The input and output data is mapped into the scanner's I/O data table based
on the device's node address and the configured fixed mapping size. The
DINT-based formula is used with the CompactLogix controller for calculating
the Input or Output data location is:
Input (Output) Offset = [(Node Address) x (Allocation Size)] / 4
The data offset value is used to account for scanners that have a fixed status
field at the start of the input or output data, for example, the 1769-SDN
scanner.
EXAMPLE
When using the default fixed mapping size of 4 bytes, the input data for the devices shown in the example
below is allocated in the 1769-SDN's input table as shown below. Notice node 1 is located in the data map
at DINT location 1, node 2 at DINT location 2, and so on.
Notice that, in this example, node 4 is unused. However, the I/O memory slot remains allocated for it.
01 02 03 05
IMPORTANT
If you are using a MicroLogix 1500 controller with a 1769-SDN
scanner, you must use the following WORD-based formula for
calculating the Input or Output data location:
Input (Output) Offset = ([(Node Address) x (Allocation Size)] / 2) +
Data Offset
In this formula the Data Offset = 66 for Input Offset and 2 for
Output Offset.