When I was able to choose a controls platform myself, there were 5 factors I would consider when evaluating a new system.
When I worked for automation distributors I was required to promote and recommend only the products that the distributor sold. This sometimes caused a conflict of interest: is this the most appropriate solution for this application? The first distributor I worked for sold Omron and Eagle-Signal PLCs. If I was in a plant that was full of Allen-Bradley controls this could be a tough sell… the customer usually had a significant investment in both hardware and training particular to A-B. In his case he was tired of paying for the yearly software licenses that Allen-Bradley charges hundreds of dollars for. Of course there was no economical way for either of us to do this, so the plant remained A-B.
The next company I worked for was an Allen-Bradley distributor. As a product specialist I learned that A-B required all of their distributors to staff several technical specialists and of course this costs money. In return Allen-Bradley distributors get protected territories and the customers get support and training on their products.
When I started my own automation company I generally had to use whatever the plant specified. This required having a lot of different software packages and of course paying the dreaded support fees to both Allen-Bradley and Siemens. There were occasions however where I was able to choose a controls platform myself. There were a variety of factors I would consider when evaluating a new system:
- Existing hardware, software and training. Is there already a majority of one type of controller in the plant? Do the maintenance and engineering departments like it and are they trained? How much support will they need?
- Cost. How much is the customer willing to spend to implement the solution?
- Spare parts. Are replacement components readily available in the local area?
- Suitability. Will a micro PLC do the job? Will there be a large amount of data that will need to be recorded and analyzed? Will the processor be fast enough/have enough memory? Are special purpose cards such as high resolution analog, servo or math/basic required?
- Ease of programming. Is the software user-friendly? Are there special purpose instructions or functions to make programming easier?
All of these things would have an impact on the platform I would choose.
