Rockwell Automation 1769-SDN Compact I/O DeviceNet Scanner Module User Manual - Manual (Page 117)

Publication 1769-UM009E-EN-P - August 2009 117
Use the 1769-SDN Scanner Module with MicroLogix Controllers Chapter 7
Data Table Address (receive and send)
This value identifies the data file location within the 1764-LRP controller that
will receive data from the DeviceNet device, and/or the starting data file
location that will be sent to the destination DeviceNet device.
Size in Bytes (receive and send)
Since all data transmitted on the DeviceNet network is byte based, you must
enter the number of bytes that will be received and sent. You must make sure
that enough memory is available in the destination device. Word elements
within 1764-LRP controllers contain 2 bytes each. These include Bit and
Integer data files. Long word and Floating point elements contain 4 bytes each.
For receive, the size in bytes entered must be greater than or equal to the
number of bytes that the DeviceNet device will return. DeviceNet devices
return a fixed number of bytes, depending on the class and service. If more
data is returned than expected, the message will be in error and no data will be
written. If less data is returned than expected, the data will be written and the
remainder of the bytes will be filled with zeros.
In the example dialog shown below, N7:0 will receive 2 bytes (1 word) of data.