Rockwell Automation 1395 ControlNet Communication Board - Manual (Page 66)

6–2 Troubleshooting
Publication 1395.5.37 – March, 1999
the fault may be cleared and normal operation resumed at the point the
fault occurred. An example of a Soft Fault is:
S CNA Comm Loss
Warning Faults Warning Faults are the lowest priority and indicate error conditions
which are generally transient in nature, but could result in undesirable
operation if allowed to persist. If left uncorrected, Warning Faults
could result in a Soft Fault. An example of a Warning Fault is:
S Class 3 Close
Selected Fault conditions in the Bulletin 1395 Drive can be configured
in terms of their Soft or Warning Fault nature. That is, the
user/operator may specify the action taken, either Soft Fault or
Warning Fault (Report Only).
!
ATTENTION: Ignoring faults that have been configured as
Report Only could damage certain components in the Drive.
Communication Fault Reporting and Handling
Connections and Transport Classes – ControlNet implements a
producer–consumer model network. The drives support configurable
point to point connections to and from other devices on the network.
Every device has a physical connection to the network, but logical
connections are also required between devices to support the exchange
of data. Two transport classes are supported by the drives on
ControlNet. These are transport class 1 and transport class 3. Class 1
connections are used to pass 8 16-bit words of I/O data (1 full rack)
each direction between a Controller and a Drive deterministically at a
configurable periodic rate. This type of data transfer corresponds to
data being shared via Remote I/O. Class 3 connections are also
supported for messaging between devices. This data is what would be
sent over Data Highway Plus or with RIO block transfer.
Types of Communication Loss – Loss of data communications can
be due to either physical or logical reasons. Below are definitions and
examples of the primary causes of communications loss.
Comm Loss – If the drive becomes physically disconnected from the
network, this is the most obvious form of communication loss. But the
drive can also lose its logical connections in a variety of ways. The
network could be inoperable due to some required device being down
or possibly if illegal data or noise is present on the network. The drive
itself may be deemed illegal on the network for various reasons and
will not be allowed to talk on the network. Any of these conditions
may be reported as a general “ICN Comm Loss”. When this condition
is reported, the drive is considered to be effectively disconnected from
the network and unable to communicate in any way on the network.