BMS

What part of the system do you manage? Is it a customer's internal phone system, or is it the central switchgear? My first suggestion is to look up the manufacturer and model of the equipment for which you are responsible, then find the operator's and service manuals. You may have to go to the manufacturer's website to get these.

Firstly can we find out what you are talking about BMS Stands for Building Mangment System. and is usually included in the comms and data cabling system. This system controls air con etc etc. i dont know what a Basic managment system is

hi thank you very much for the stuff.. yeah your right its the BMS as you defined. I am sorry, I noticed I mentioned Basic Management System that confuses some guys up here. Yeah the task was focused on the Fire alarms, Air Handling Units, Lighting and Irrigations. For the past few days , I noticed that the system has been used to execute commands like turning on and off the AHU's, Irrigation Solinoids, Alarms, lightings etc. and set up time schedules. So if I am not mystaken, BMS aside from Building Management System, its the human interface to to make the whole thing works. Now I want to disect this thought into pieces like knowing how the computer and the switches commmunicates? how this stuff works? - thanks

There are many ways to design a computer-controlled Building Management System. It could be as simple as a cabinet of relays switched by an I/O port card, or as sophisticated as Ethernet devices addressed over the building's Local Area Network. There is no way we can tell without looking at the system or reading the installer's documentation, unless there are clues in the software configuration. Exception to the previous statement: if the system is a commercial off-the-shelf design, somebody might recognize it from the brand name and model of the software or the control cabinet.

If you don't have the documentation, get it. (Ask the building engineer or architect if you can't find a product name.) You'll need it to do your job effectively without wasting days trying to reverse-engineer the system when something goes wrong. In the meantime, try looking at the cabling coming out of the computer to see where it goes, or you could look at some of the controlled devices to see where and how the control signal comes in. That will tell you what the physical layer is like.

You may be able to look through the BMS software to see how it works also. When you get brave enough to experiment, do something relatively harmless like turning lights on and off after hours. You don't want to accidentally call in the Fire Department!