NetDecoder - ControlNet Analyzer:
Sniff, Analyze, Debug and Troubleshoot
- ControlNet analyzer provides a comprehensive troubleshooting
and diagnostics solution for solving communication problems on ControlNet
The ControlNet analyzer supports two of Rockwell Automation's interface
The NetDecoder analyzer uses these cards as the sniffer interface into the ControlNet
network. The startup wizard provides the options to run the analyzer using
either of these two ControlNet interfaces.
The NetDecoder analyzer provides a wide range of features to simplify troubleshooting
These features include:
ControlNet Capture Filters
The ControlNet analyzer provides the ability to set capture filters while
sniffing network traffic. Capture filtering allows frames that meet a
specified condition to pass from the network to the file. If the frame does
not satisfy the filter criteria, it is thrown away. Data that is filtered
out using a capture filter cannot be recovered.
Filtering is very helpful to
weed out unwanted messages and isolate messages that cause trouble. The
reduced traffic allows the network analyst to concentrate on thorny issues
and thereby reduces debugging time. The user interface for defining filters
changes depending upon the sniffer interface being used.
While using the 1784-PCC card, the Capture filters are accessed through the
I/O Settings dialog. The user can define the Capture Filter based on:
The dialog for defining the filter is the same as that for
defining a trigger for the 1784-PCC. If a value is not entered for
the Producer or L-Packet Prod/Cons MAC ID, then the full range
(0-255) is selected. The frame status can be Good, Bad or Null. The
frame types are Scheduled, Unscheduled and Moderator.
The capture filters for the 1784-U2CN sniffer interface are also available
on the I/O Settings dialog. The capture filters in this case can be defined
Once again the options for defining frame status are Good, Bad and Null.
This is the status of the frame as received by the CNA10 ASIC. The options
for defining the frame types are Scheduled, Unscheduled and Moderator. These
definitions are consistent with those in the official ControlNet
specification. The additional filter option available in the 1784-U2CN
interface is that of disabling timestamps. ControlNet traffic has a bit rate
of 5Mbps. When there is heavy traffic on the network and the network
utilization is high, the hardware can drop packets in promiscuous mode. To
avoid dropping frames, the user can disable timestamps and improve packet
ControlNet Start and Stop Triggers
The ControlNet analyzer also provides the user with the ability to set Start
and Stop triggers.
The triggers are defined a bit different for the 1784-PCC interface and the
While using the 1784-U2CN sniffer interface, the ControlNet analyzer defines
start and stop triggers on the basis of the frame MAC ID and the
Producer/Consumer MAC ID. The user can enter any legitimate value for these
IDs and the ControlNet analyzer will trigger accordingly. The user can set
the triggers in the I/O settings dialog.
While using the 1784-PCC sniffer interface, the ControlNet analyzer defines
start and stop triggers similar to the definition of Capture filters. The
triggers are based on a combination of Produce MAC ID, Frame Status, Frame
Type and L-Packet Producer/Consumer MAC ID.
ControlNet analyzer uses the 1784-U2CN or the 1784-PCC card as the sniffer
interface. The interface cards are designed around the ControlNet CNA10 ASIC.
The ControlNet analyzer gathers information about frames dropped by the
CNA10 ASIC. The protocol analyzer also provides the number of frames that
were dropped by the buffer in the 1784-U2CN device.
Other useful ControlNet related error information includes the number of bad
frames received and the MAC IDs of nodes transmitting bad frames. The
ControlNet analyzer maintains a list of the last eight MAC IDs that
transmitted bad frames.
ControlNet Network Monitoring
- ControlNet analyzer based on the 1784-PCC card, provides a
Network View display. This view provides a complete grid-layout of all the
nodes. The layout reflects the status of RSWho status inquiry of the
network. This display is consistent with the feature provided by Rockwell
Automation's ControlNet traffic analyzer. Active nodes are highlighted in
green and non-existing nodes are shown in grey. Nodes that drop off the
network instantly turn from green to grey indicating a problem. This change
in device status points the network administrator in the direction of the
Apart from, the network layout, the ControlNet network view also provides
The ControlNet analyzer also provides the used and available scheduled
and unscheduled bandwidth information. This information is very useful for
troubleshooting problems on a ControlNet network.
ControlNet Hardware Settings
Hardware Settings for the 1784-PCC sniffer interface
The Hardware Settings display provides the current status of the installed
1784-PCC card in the following fields:
The 1784-PCC card is also used by other applications such as
RSLinx. Only one application can have access to the 1784-PCC card at
a time. When one of these applications is running, it locks the card
and prevents other applications from accessing it.
Hardware Settings for the 1784-U2CN sniffer interface
The Hardware Settings dialog allows you to select a device to
sniff/scan. You access the Hardware Settings dialog by selecting Hardware
Settings from the Options menu on the NetDecoder Control window. NetDecoder
automatically scans and identifies all the 1784-U2CN devices plugged into
the PC. These devices, identified by their Serial Numbers, are displayed in
the drop-down list of Available Sniffers.
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