Beginning the process, The example network, Beginning the process the example network – Rockwell Automation 1747-SDN SLC 500 DeviceNet Scanner Module User Manual User Manual
Page 24
Publication 1747-UM655B-EN-P - June 2007
24 Planning Your Configuration and Data Mapping Your Devices
Beginning the Process
Planning before configuring your 1747-SDN module helps you do
these things:
•
Use your memory and bandwidth efficiently
•
Cater to device-specific needs and requirements
•
Give priority to critical I/O transfers
•
Leave room for expansion
You need to know what is on your network. You should be familiar
with each device’s:
•
communication requirements.
•
I/O importance and size.
•
frequency of message delivery.
At this point in your planning, it is advantageous for you to have some
idea of how the network could be expanded. I/O data mapping can
be performed automatically by the RSNetWorx software. But when
mapping your I/O, you also have the opportunity to allot room for
future I/O. This can save time and effort in the future.
For example, RSNetWorx software automatically maps the devices as
efficiently as possible, but the result is that multiple devices may share
the same word location in memory. However, you can also have the
system map the devices such that no two devices share the same
memory location by selecting the Dword align option when
performing automapping. You can also manually map the devices if
you need to assign or reassign them to specific memory locations.
For details, refer to the Help dialogs provided by the RSNetWorx for
DeviceNet software. Additional support can be found at the Rockwell
So
The Example Network
The following example illustrates a data mapping plan for a
DeviceNet network. Note that even if the mapping is performed
automatically by the RSNetWorx software, you must know where the
devices are mapped in order to use them in your network.