Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 177)

Publication 1757-UM006A-EN-P - May 2002
Using the 1788-CN2FF, ControlNet-to-FOUNDATION Fieldbus H1 Linking Device 7-17
Figure 7.10 Sample NI-FBUS Configurator View of ControlNet Object Information
Changing the Linking Device Configuration
Once a configuration is created in the linking device and a PLC
processor or PC is using the offsets previously defined, an addition to
the configuration should not require you to change functioning code
in your application. For this reason, once a configuration has been
stored into the linking device, if the user wires more Fieldbus devices
with NI-FBUS, additional object instances are created and additional
offsets are appended to the assembly objects; the existin.
The individual instances increment from the last one used in the
category. The offsets within the assembly objects are assigned in the
same order as described previously, but are placed after existing
offsets. For example, assume you have two MAI channels and one
MDO channel with cascade initialization. The instances and offsets are
created. Sometime later, you need to add an additional MAI channel
and two MAO channels to your configuration. These additions are
placed after the final MDO from the previous configuration.
Because existing programs may be using a configuration, the deletion
of a linkage from a Fieldbus network does not result in a renumbering
of ControlNet objects or a reordering of the assembly object offsets. If
the Fieldbus device is no longer present, Fieldbus and ControlNet
status indicates an error condition, and the object and assembly offset