Essentials to Know About DeviceNet Protocol
From an operational perspective, DeviceNet is basically a low level network protocol used in the industrial automation applications. It is mainly used in the automation industry to interconnect different industrial control devices across processes in order to facilitate data exchange. Typically, DeviceNet is used to connect simple industrial devices such as sensors and actuators with higher level more complex devices such as Programmable Controllers.
It is built on the Controller Area Network (CAN) which was developed by Bosch, as an application layer protocol and it makes use of the Common Industrial Protocol and of course the CAN hardware to perform its duties and to connect with a range of different device profile, configure them and control those devices. For the same reason, it is low in terms of cost and according to Kim Steven of Equustek Solutions Inc. it is also more robust when compared to other traditional RS-485 based automation protocols.
It is a technology that was originally developed by the American company called Allen Bradley. Currently, the technology has been shared with third party vendors and is managed by the Open DeviceNet Vendors Association.
What is DeviceNet used for?
The DeviceNet protocol being a low cost open source communication network, has several advantages when it comes to industrial automation. Hence it is quite popular and in demand. From a generic perspective it is used to automate different processes efficiently. Typical DeviceNet applications across industries include:
Packaging and handling of material
It can be applied to any kind of a control mechanism requirement, from simple toggle on and off controls to the process control of entire batches in manufacture.
How does DeviceNet work?
As DeviceNet supports all levels of devices from simple sensors to advanced controllers, it uses a trunkline-dropline topology, with the main line connecting to smaller lines.
It generally powers devices directly with the help of cables, with the exception of some devices which may need separate external power. It also facilitates numerous data exchanges from cyclic to polled to strobed.
At the point of connection with the network, the node has to have a distance of not more than 6 metres from the trunkline. Up to 64 nodes can be typically supported and its end-to-end point may vary depending on the baud rate.
It mainly uses the Common Industrial Protocol for its upper layers, which adheres to the Open Systems Interconnection model across seven layers; physical, session, data link layer, network, presentation and finally the application layer where DeviceNet belongs.
It is commonly used in technologies like push buttons, detection sensors and the like and it doesn’t support any pressure or flow devices generally, although with an integrated DeviceNet a flow meter or a converter may be present.
How to configure DeviceNet
Configuring DeviceNet requires careful deliberation and accuracy. For the smooth configuration of the technology, the RSNetWorx for DeviceNet must be used.
One can easily configure DeviceNet online by creating a new configuration online. After that the RSWhoBrowse utility can be used to choose an effective communications driver for the process.
Once this is done, a graphical overview of the network will be available on configuration view.
After creating the new configuration each and every device that is part of the DeviceNet network must be separately configured in, along with configuring the entire network.
The next step is to configure the scanners on the DeviceNet network. After all the devices are separately configured, one can save it and subsequently log back in to diagnose and troubleshoot any issues with the network easily.
Typically DeviceNet protocols are largely preferred due to their fast installation times, low costs and high efficiency.