Enables industrial devices to use multiple fieldbus languages ​​without hardware translation

In the early days of industrial process control, industrial devices (sensors and actuators) were individually connected to programmable logic controllers using dedicated wires carrying analog (4-20mA) current signals. However, as processes became more complex, the number of inputs and outputs required also increased, making cabling complex and unwieldy, and troubleshooting increasingly difficult.

Therefore, industrial digital fieldbus networks were developed to reduce wiring by transmitting multiple control and measurement signals over a single cable (bus).

While this brought about a breakthrough, several other proprietary fieldbus networks later emerged, preventing a single standard from being established. This resulted in multiple versions being used in various factory settings and industrial equipment that were compatible with some versions of the fieldbus but not with others.

Some of the most common fieldbus networks today include:

Prophibus

Modbus

Canopon

These protocols differ in the number of devices supported, language syntax, and physical interfaces used. Recently, several incompatible real-time fieldbus networks (which operate over Ethernet) have been developed, including:

Ethereum Cats

Profit

Ethernet/IP

One of the major decisions for manufacturers is the fieldbus network for their equipment. The traditional approach is to purchase a third-party communication module to allow the equipment to communicate on this network (Figure 2).

Figure 2: Block diagram showing how an industrial device can communicate with a fieldbus using a communication module.

While this is a low-risk and convenient solution, it comes with several less obvious disadvantages. The most obvious (and most important) limitation is that it restricts the device to communicate only with the version of the fieldbus that the module implements, thereby narrowing the potential market to customers who use that version of the fieldbus in their plants. Enabling the device to operate on other fieldbus networks requires repeating the process and procuring different modules for the new version of the fieldbus. Since the communication modules come in different footprints and are pin-incompatible, this redesign can be expensive and time-consuming.

Using dedicated hardware also makes it more difficult to add additional features and functionality to the device design. In addition, manufacturers have no control over their supply chain, as communication modules can usually only be sourced from their manufacturer. This can lead to unexpected production downtime if supply is unexpectedly interrupted. Another hidden cost of this approach is that some component suppliers require royalties, resulting in unavoidable overhead that persists throughout the product's life cycle.

Break free from hardware constraints

The new paradigm that allows manufacturers to break this accepted model is to use a software stack running on their device microcontrollers to enable them to join the fieldbus network. This approach completely eliminates the requirement to use expensive communication modules, thereby reducing the bill of materials and also brings several other advantages. It greatly increases the flexibility of product design because the software stack can be easily modified to provide customized features and functions. In addition, manufacturers can have complete ownership of their supply chain because they no longer need to purchase hardware from third parties.

In addition, by modifying the code in the software stack, the device can be quickly retargeted to communicate with an entirely different fieldbus, allowing new products to be brought to market faster than with a hardware redesign. The software-based approach also makes it easy to add innovative and customized features to high-end products by modifying the code in the stack.

Proven fieldbus stack

RT-Labs' U-Phy is an example of a software-based approach that enables devices to quickly communicate over multiple industrial fieldbus networks via Profinet and EtherCAT. This pre-certified software stack runs on an open hardware design, eliminating the need to pay for additional royalties and proprietary hardware.

Fieldbus industrial communications bring many benefits to industrial process control systems in factory environments around the world. However, the traditional approach to allowing industrial devices to communicate on a fieldbus network is to use “off-the-shelf” communication modules. While this provides a low-risk solution, it has several disadvantages, including high cost, lack of flexibility in product design, and potential supply chain disruptions. Using a fieldbus software stack is an alternative approach that reduces bill of materials costs, increases flexibility and innovation in product design, and reduces risk by allowing manufacturers to fully control their own supply chain.