PROFINET offers many features for custom-tailored architectures and automation applications. One of these features is “PROFINET Shared Device”, which gives multiple PROFINET IO controllers access to the same IO device. This article covers an introduction, overview, and application examples for this feature.
How Does “PROFINET Shared Device” Work?
“PROFINET Shared Device” offers a device the ability to support connections to more than one controller at the same time. When configuring a shared device, users can set up input and output modules to be exclusive to separate IO controllers or inclusive. The following diagram helps explain the main concepts. The diagram shows two controllers. One is a standard controller and one is a safety controller (PROFIsafe). The IO device has 4 modules, two input modules, and two output modules. IO controller 1 can be set up to exclusively control the first input and output modules (Orange). While IO controller 2 could be set up to control only the second input and output safety modules (Blue).
IO Controller 1 also sets up the PROFINET interface and network ports on the device (the first big orange slot). In addition, IO Controller 1 handles any diagnostic/process alarms from its modules(ie. module pulled or a fault like a wire break). While IO controller 2 will handle any alarms from its associated modules.
Next is another example, which allows more flexibility. In some automation applications, several controllers may need to have access to the same input data. In this case, users can set up shared inputs with two controllers (safety is also possible). Now both IO controller 1 and IO controller 2 have access to the inputs from the device. And each controller has exclusive access to their own output modules. With the input data, each controller can act accordingly by sending down their proper output values.
Note that a device which supports sharing must allow for at least two controller connections. But, can support greater than two depending on the device type and device manufacturer. Some devices can support four or more connections.
Implementing the “PROFINET Shared Device” feature brings several benefits. First, it reduces the necessity for additional hardware, cabling, and cabinet space. It allows flexible assignment of multiple IO controllers to the same device, custom tailor architectures, and mix failsafe and standard IO on the same device. Finally, it is possible to separate exclusive input/outputs to multiple controllers, or even shared inputs between multiple controllers.
This article originally appeared as a lesson at PROFINET University