Sorting through the marketing terms

With many vendors creating many more acronyms for their system, deciding which one is for you can become a difficult task. These terms are used so loosely at times, all systems, including ours, could potentially qualify. We have used our knowledge of each system to provide an analysis of the two primary systems used in the water and Wastewater industry.

Master-Slaves System
The Master to Slaves approach simple: A central "master" station redirects and send appropriate commands to the individual remote sites. These remote sites don't talk directly to each other and require the assistance of a master station to keep up to date on system conditions and setpoints.

Many vendors insist that this system is a single point of failure, and if it fails the world ends. Mitigating these potential scenarios is not a difficult process. We have implemented multiple-master, redudancy systems many times for water and Wastewater companies.

Advantages
Lower cost.
Easier learning curve.
Lower replacement costs.
Centralized control and monitoring.
Simplified software upgrade process

Disadvantages
Requires the master to be available. (Fix: Redundancy)
If the master is gone, you have no idea what is happening; good or bad! (Fix: Redundancy)
We don't make as much money.

DCS or Distributed Control Systems
Generally used to convey the idea that all the functions are spread across the system and in the event of a failure the system continues to operate without a "master station." The idea of distributed control in water systems is this: Keep my tanks at the ideal levels and don't make me call the health department. SCADAspire PLC software has integrated features that continue to operate in the event of a "master-failure."

One idea that is generally left out of the examples for a DCS system is in regards to equipment replacement due to a local failure at the site. Keeping spare units in the event of a failure can be costly, as well as the software that is different from tank or well control units. SCADAspire systems provide the same software in every unit. If a unit fails, replace it with a spare, or if mission critical temporarily use another unit that is not as important.

Advantages
Operates without a master-station. (That is what redundancy is for!)
Zones can work indepedantly for local-control. (We offer local control too!)

Disadvantages
Higher system costs.
More to learn.
Every site type has different software (tank vs well), adding to replacement cost.
Replacement cost.
We don't make any money?