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Allen-Bradley ControlLogix Ethernet Driver Help

Each device has now been defined under its own channel. In this new configuration, a single path of execution is dedicated to the task of gathering data from each device. If the application has 256 or fewer devices, it can be optimized exactly how it is shown here.

The performance will improve even if the application has more than 256 devices. While 256 or fewer devices may be ideal, the application will still benefit from additional channels. Although by spreading the device load across all channels will cause the server to move from device to device again, it can now do so with far less devices to process on a single channel.

Performance Statistics and Tuning

The Performance Statistics feature provides benchmarks and statistics about the Allen-Bradley ControlLogix Ethernet application's performance. Because Performance Statistics is an additional layer of processing, it can affect the server's performance. As such, the default setting is off. To enable the Performance Statistics feature, open Device Properties and select the Logix Options tab. Then, check the Enable Performance Statistics box.

Types of Performance Statistics

Performance Statistics provide meaningful numerical results across three scopes: device, channel, and driver. Descriptions of the types are as follows:


Device: These statistics provide the data access performance on a particular device.


Channel: These statistics provide the average data access performance for all the devices under a given channel with Performance Statistics enabled.


Driver: These statistics provide the average data access performance for all devices using the Allen- Bradley ControlLogix Ethernet Driver with Performance Statistics enabled.

Choosing a Statistic Type

The type of statistics needed depends on the application. In general, driver statistics provide a true measure of the application's performance, whereas channel and device statistics are most relevant while tuning the application. For example, will moving 10 certain tags from Device A to Device B increase the performance of Device A? Will moving Device A from Channel 1 to Channel 2 increase the performance of Channel 1? These questions are good examples of situations when device and channel statistics should be used.

Locating Statistics

Server statistics are outputted to the server's Event Log upon shutdown. To view the results, shut down the server and then restart it.

Differences Between Server Statistics and Performance Statistics

Performance Statistics provide the makeup of the types of reads performed (such as symbolic vs. symbol instance vs. physical, or device reads vs. cache reads) whereas server statistics provide a general read count value.

Tuning the Application for Increased Performance

For information on increasing device and channel statistic results, refer to the instructions below. For more information, refer to Optimizing Your Communications.

  • 1.

    Server Tags referencing Atomic Logix Tags (array or non-array) should be assigned to Logical Non- Blocking devices.

  • 2.

    Server Tags referencing a Structure Logix Tag composed of one-third or less of the Structure Tag should be assigned to Logical Non-Blocking devices.

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