Remote Site Monitoring/Alarming

Had to do a job yesterday where we needed to set up remote site alarming for our client. In this case the client specified the hardware to be used and hence this article. When you do these installations, it is critical that you match the different types of hardware to your “back to base” unit.

The installation was set up with a number of pressure indicators but the design is such that we do not have voltage free contacts. So far this is not a big issue. The problem only occurred when the back to base unit was installed as this had its own power supply internally. In reality not a massive problem provided you are not on a very remote site when this happens.

Easy fix though, just had to wire in some relays very quickly to provide us with some voltage free contacts. This works but it is obviously not the most economical way of doing things. This does however lead me to the following: Mitsubishi Alpha controllers. These little units are incredibly powerful, easy to program and will not break the bank. Let’s take a look at how this would have worked in this application.

The outputs from the pressure devices would hook directly to the inputs of the controller. Write a very basic program to react on the signal, bring up a screen display to identify the alarm state and write this to the GSM block. You will need to add a GSM modem and the cable between the two units.

In the program you set up the message centre and the phone numbers you want to send the message to. Like I mentioned, these units are very easy to program. All the programming is done with LOGIC BLOCKS. If this is something that would interest you, I could set up some screen shots of a typical program with some explanations on it to help get you underway.

Keep in mind, these units can be used for controlling smaller machines, very powerful timers, counters etc. You could even set them up so that you can send a message to them from your phone to carry out an instruction. Just before anyone asks, No, I don’t sell them at all. I just love using them. I have set up so many programs with these and have not had one unit fail in almost 10 years since I started using them. Some of the sites where these units are installed would destroy many expensive PLC’s yet these little units just last

Let me know if this is something you would like to know more about. If there are enough requests I will set it up as a general Post for Members. Till next time, works safe and be proud of what you do. Make sure you retain the passion for what you do.

By the way, don’t forget to check out the Manual for Electricians Volume one available from