Rockwell Automation 1788-CN2FF ControlNet-to-FOUNDATION Fieldbus H1 Linking Device User Manual - Manual (Page 40)

1788-6.5.1 - January 1999
4-14 Using the ControlNet-to-FOUNDATION Fieldbus H1 Linking Device
Alarm Handling by the HMI The linking device makes the process alarms from AI and DI function
blocks visible as attributes of the created ControlNet objects, as discussed in
the previous sections. Fieldbus devices generate other types of alarms; for
example, they send out an alarm whenever their static configuration
changes. Other function block types also generate alarms. In general all
alarms, except the AI and DI process alarms, must be handled by a Fieldbus
HMI. You must configure the linking device to receive such alarms and
forward them to a PC-based HMI on ControlNet. You set up the linking
device as shown in Figure 4.10.
Figure 4.10 Setting Up an Alarm
If you connect the AI and DI alarms to the linking device, the linking device
forwards all alarms from these to the HMI. The process alarms are also
visible to your PLC processor through the ControlNet objects. You must
ensure, through your application design, that either the HMI or the PLC
processor acknowledges the process alarms.
Assembly Objects For each channel that you connect on the MAI, MAO, MDI, and MDO
blocks, the linking device creates an instance of a ControlNet object
corresponding to the type of channel. These individual instances are useful
for unscheduled querying and setting object information. For scheduled
communications on ControlNet, the linking device takes specific attributes
from the corresponding object instances and combines them into input and
output assembly objects.
The linking device uses input assembly objects to produce data on
ControlNet and output assembly objects to consume data from ControlNet.
The definition of assembly objects is determined after you configure the
MAI, MAO, MDI and MDO blocks on the linking device. Assembly offsets
are 0 based and increment by the size of data placed into them.