Please suggest a plc that is easy to use.

I am new to this forum and PLC's so please explain in detail what I need and who to buy from. I grow microalage and need a simple PLC to control illumination based on the density of the microalgae
I will try to exlain.

I would like purchase a PLC that will communicate with an optical density probe. The optical density probe would send 4-20ma outputs to the PLC. The PLC would control 20 lights . Each of the 20 lights would be 200 watt flourescent lamps. For example, Dictaed increasing density I need increasing light intensity. Light #1 would be on all the time, light number 2,3,4,5,6 etc would turn on and stay on with increasing density. I have everything but not sure hwat/ where to buy the right PLC. Any info about this would be greatly appreciated.

You will need a PLC with at least 20 discrete outputs and one analog input. You will also need software to program the PLC and a cable to connect the PLC to your computer running the programming software. Many of the PLCs of the size you need do not have ethernet communications, so you will need a serial port on your computer for communications. If you don't have a traditional COM port on your computer and have to use a USB/serial converter, be aware that not all of those converters play well with PLCs. It's another detail you have to contend with.

Any of the major brands have a PLC that can meet your needs. Most of the major brands are sold through distributors. Consequently, the quality of local support can vary widely. The notable exception is Automation Direct. They do not rely on local distributors. Rather, you do business with them by telephone or internet.

Major brands that sell through distributors include Siemens, Allen Bradley, GE Fanuc, Omron, Mitsubishi, Schneider.

My suggestion is to find out what other people in your area are using and where they buy them from. That will help lead you to the most reliable suppliers.

Since this is most likely a one off application, it would be cheaper to pay someone to program the plc for you. That way you can avoid buying the software and cables. Plus, you will not have to learn plc programming.

Depending on what he is really growing, contracting someone else may not be desirable.


Serioulsy though, I'll second Ken. Find out who the local AB, Siemens, Omron distributors are and ask them to recommend someone who can help with the design and programming. Be aware that the person recommended by brand X distributor might actually recommend that you use a brand Y PLC for your application.

What you are asking for sounds quite straight forward.

Just about any PLC will satisfy your requirements.

However, when purchasing a single unit, you will need to factor in the cost of the software as part of the cost of the controller.

There are some companies, including mine that don't charge for the software.

Also, if you are looking for someone to program your controller, we also offer that service as well.

Based on your requirements, our SK1600-RIC would be more than sufficient to meet your I/O requirements.

Information can be found at www.entertron.com/sk1600ric.htm

If you have any questions, feel free to contact me to discuss your application in greater detail.

God Bless,