Rockwell Automation 1336T ControlNet Frn1.02 Rev 1.5 - Manual (Page 195)

7–7 Troubleshooting
Publication 1336 FORCE–5.18 ––March, 1999
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.
Closed Connection – The drive is implemented as an adapter device on the
network and does not inititiate connections. One scanner device is allowed
to make a Class 1 connection to a drive. Many devices of various kinds can
open Class 3 connections to the drive at any time. When this happens, this
may be reported as a “Class 1 Close” or a “Class 3 Close”.
Connection Timeout – All connections, once opened, must be maintained
at some rate. If the drive does not receive data from from any open
connection within some period of time, a timeout condition is flagged. This
event can be reported as “Class 1 Timeout” or as “Class 3 Timeout”.
Controller Not in Run Mode – In addition to a loss of data due to network
errors or connections being lost, data may also be considered lost if the
controller goes out of run mode for any reason. Data being received from a
controller that is not in run mode is considered to be unreliable and is ignored
by the drive. The condition of a controller transitioning out of run mode can
be reported as “Reset/Prog/Test”.
Actions Resulting from Loss of Data – Any of the communication losses
described above can be handled in various ways. The condition can cause a
soft fault, which will cause a drive to stop active operation. The condition
can be reported as a warning which means the event is annunciated, but does
not change the running state of the drive. The condition may also be ignored.
Beyond this, the handling for the loss of the Class 1 I/O data can also be
configured with “Last State” bits that are defined in a subsequent section of
this document. These bits are used to define the action to be taken with the
Input image being used by the drive. This image can be either left in its last
received state or it can be zeroed. Loss of I/O image would occur for the
following conditions:
Reset/Prog/Test
ICN Comm Loss
Class 1 Close Class 1 Timeout