The selection of SCADA hardware is a little more difficult, as various manufacturers have both strong and weak points.
We recommend Open Architecture products
Open Architecture does not mean that you can take a module from one manufacturer and use it in another manufacturer’s product. What it does mean is that various manufacturer’s ‘subscribe’ or ‘utilize’ one or more ‘open’ protocols, so they can communicate with other products.
For the SCADA industry, the de facto protocol is Modbus. Most manufacturers now utilize Modbus, allowing various products to communicate with one another.
We always recommend hardware that is intelligent and modular in design. Modularity allows for the addition or change of various modules, without having to replace or remove the entire device. Intelligence allows for the device to handle ‘local’ or ‘standalone’ programming, which we believe is crucial for a good system design. These include, but are not limited to:
- GE Fanuc
Above all, there must be a wide-variety of Input/Output module choices and the ability to easily write the application logic programming.
We believe it is crucial for the hardware products to be able to communicate well over a wide variety of communications media. Our favored choice is RF, as it is the most reliable and cost effective.
However, it is also important for the RTU/PLC to be able to communicate to one or more other devices. To that end, we find Modbus not to be a suitable protocol for radio communications. While the master/slave and sub-master relationships do offer some solutions, we find that a true ‘peer’ to ‘peer’ communications protocol is best.
Some products work well over telephone lines, but fail miserably when it comes to radio communications. We carefully evaluate the product and system before making recommendations.