Answer: They are high quality industrial transmitters packed with great features. Since the start of the design we have always placed our attention to durability and availability in an industrial environment.

Years of experience in the business have positioned our products among the best and more creative products available.

Answer: Even if you know that the load added by the devices in the loop totalizes more than 250 Ohm (that is the minimum load needed to communicate HART). It is NOT recommended to eliminate the classic 250 Ohm resistor from the current loop.

Consider this.

Let's say you are going to do maintenance on one device in the loop.  When you remove this device from the loop and take it to the workshop. Let assume that you shorted the 2 points where this device was installed, so the loop keeps closed.  In this situation, the total load now could get lower than 250 Ohm based on what was left on the loop.   If this happens, the HART communication in the line is compromise and may not work anymore.

On the other way, put in mind that too much load in the line may require a higher voltage power supply for the loop.

Answer: SMAR carries many devices with built-in PIDs and other control algorithms. These controllers are present in dedicated controllers, transmitters, PLCs, and in or modern DCS (Distributed Control System), the System-302.

However, I believe that your question is in reference to PID controller units for panel installation, with its own display and buttons interface to interact directly with the user.

For this case I should recommend you to look at the CD600Plus.

The CD600Plus is a stand-alone multi-loop controller that can resolve up to 8 PID controls.  It is block configured in an easy to use Windows graphical interface.

See more on the CD600Plus

Answer: Let me start by saying that a smart HART® transmitter can also provide the 4-20 mA as an old good analog transmitter.

A HART transmitter can directly replace an old analog transmitter that you already have installed and running in the plant.

You can literally remove the old analog transmitter and replace it with a HART one. Yes, it is compatible with your power supply and the twisted pair of wires used before. Just a brief and important point.  You will need to add a 250 Ohm resistor in the loop to be able to communicate with the transmitter.

There are many advantages that a HART transmitter can bring to your plant and operations.

When we understand those added features, we can say that they are a better asset to the plant!

Some immediate benefits are:

1. Configuration can be done remotely using a HART interface to communicate with the transmitter through a computer or using a hand-held.
2. Now users have a digital access to the signal and other internal parameters
3. Considering they are microprocessor-based (smart), they can make internal calculations as PID control, Square Root, Totalization, linearization, filtering, …
4. Better and easier for diagnostic and routine maintenance
5. Manufacturers add troubleshooting information
6. Better integration with a DCS (Distributed Control System)