Mature Technology
Being referred to as “mature” sounds much better than simply being called old. It conjures up an image of being learned to the ways of the world. Think about mature trees in a mature neighborhood, where, dare I say, mature people live. Or houses that hold their value and don’t change hands very often, where there’s a sense of security and safety. Could the same be said for technologies?
What customer wouldn’t want to buy a solution that is tried and trusted and “mature”? This is especially true in the world of factory and process control, where inertia toward a working solution is often preferred over an upgrade.
What is 4 – 20mA?
The well-recognised 4 – 20mA protocol is widely used in process control environments for transmission of analog signals. This includes temperature, flow, and pressure, with 4mA representing zero-scale and 20mA representing full-scale. It’s generally more resistant to noise, especially over long cable lengths, compared to voltage signals. Opens, shorts, and sensor faults are easily diagnosed.
There are some limitations with the transmission of analog information over 4 – 20mA. These limitations include only supporting single-variable data transmission, lacking error correction compared to some of its digital competitors, and the need for regular calibration due to its analog signal. But even with these limitations and the shift toward more digital transmission, the technology has stood the test of time due to its simplicity, reliability, and noise immunity.
Figure 1: Pecan trees can live for 100 to 300 years.
Longevity in the Industry
Longevity is a key consideration in industrial end applications where mission profiles of up to 30 years are often requested. Trusted suppliers who have supported products for decades are highly valued in the industry and rank high on customers' selection criteria. Analog Devices extensive 4 – 20mA solutions are tried and trusted within the industry.
Mature, with an Eye on the Future
Product refreshes happen regularly with customers, often influenced by cost and procurement teams. Ideally, any replacement product must ensure the system performs at the same level and functionality as the previous generation.
When exploring new investment areas aligned with the factory of tomorrow, it’s easy to fall into the trap of comparing the latest technology with what it’s going to replace – the old technology. As factory architectures evolve, it is true that 100% IP addressable end nodes are one potential vision of the future. With many 4 – 20mA suppliers supporting backwards compatibility or guaranteed lifetime operations, a complete switch to new technology may not be a viable option. Depending on which marketing report you read, it is clearly going to be a transition. What is also clear is the demand to support 4 to 20mA applications in the future.
Configurable solutions like the recently released AD74416H, a quad-channel, software-configurable input and output with HART modem, support mature 4-20mA communications. The product was designed to support backwards compatibility, enabling the future direction of the industry, while addressing existing pain points. These include integrated HART per channel to add enhanced diagnostics, adaptive power switching to manage heat concerns, and built-in diagnostics that are valuable in safety applications. The configurable nature of this type of solution can also address the challenge faced by the procurement teams, including using a single platform solution to reduce inventory levels and thereby reduce the overall lifetime cost of the solution.
A Mature Decision
The question remains whether mature 4-20mA technology should be considered as legacy. Let’s flip that question on its head; 4-20mA products have made a lasting impact in the industry, a legacy that will continue to be supported by recent investments where innovative approaches, including power optimization and reconfigurability, continue to deliver substantial value in solving end customer challenges. Coupled with extended mission profiles and resiliency of supply for a 30+ years lifetime, mature decision making will ensure that Analog Devices’ portfolio of 4 – 20mA products will continue to be designed into both legacy and future-looking end customer applications.
Read all the blogs in the Configurable Industrial I/O series.