Specifications

Allen-Bradley DH+ Driver Help

Optimizing Your Allen-Bradley DH+ Communications

The Allen-Bradley DH+ Driver has been designed to provide the best performance with the least amount of

impact on the system's overall performance. While the Allen-Bradley DH+ Driver is fast, there are a couple of

guidelines that can be used in order to control and optimize the application and gain maximum performance.

Our server refers to communications protocols like Allen-Bradley DH+ as a channel. Each channel defined in the

application represents a separate path of execution in the server. Once a channel has been defined, a series of

devices must then be defined under that channel. Each of these devices represents a single Allen-Bradley PLC

from which data will be collected. While this approach to defining the application will provide a high level of

performance, it won't take full advantage of the Allen-Bradley DH+ Driver or the network. An example of how the

application may appear when configured using a single channel is shown below.

Each device appears under a single Allen-

Bradley DH+ channel. In this configuration,

the driver must move from one device to the

next as quickly as possible in order to gather

information at an effective rate. As more

devices are added or more information is

requested from a single device, the overall

update rate begins to suffer.

If the Allen-Bradley DH+ Driver could only define one single channel, then the example shown above would be the

only option available; however, the Allen-Bradley DH+ Driver can define up to 100 channels. Using multiple

channels distributes the data collection workload by simultaneously issuing multiple requests to the network. An

example of how the same application may appear when configured using multiple channels to improve

performance is shown below.

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 100 or fewer channels, it

can be optimized exactly how it is shown

here.

The performance will improve even if the

application has more than 100 channels.

While 100 or fewer channels 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.