• Home
• Knowledge base
• Why sensors have no name

Why sensors have no name of their own, and how they get one

Ask a person about a sensor and they say, "the temperature in the server room". Ask the equipment and it says something like "input 7". Neither is wrong, but only one of them helps you find a fault.

What a controller actually knows

A controller knows its sensors by their position on the controller: the first input, the seventh input, and so on. Whoever installed the equipment decided which sensor went where, and the controller has no idea whether input 7 is in a server room, a freezer or a boiler house.

The meaning lives somewhere else: in an installer's notes, in a drawing, in a spreadsheet, or simply in somebody's memory. On many sites that person has moved on.

Why this causes trouble

• Two different sites can both have an "input 7" that measure completely different things.
• When something stops, a bare position tells you nothing about where to walk.
• Different people describe the same sensor in different ways, so a list quickly becomes confusing.

How a sensor gets a name

In Bhairava Sense, the equipment is found by itself, and then you give each sensor its meaning. You drag the sensor onto the branch of your site tree where it belongs, and you type a name. From then on, the place and the name are what you see, instead of a position number.

Choosing a good name

• Say it the way you would to a colleague. "Cold aisle temperature" is better than a code.
• Put the place in the tree, the thing measured in the name. The branch already says "Server room", so the name does not need to repeat it.
• Avoid shorthand only you understand. Someone else may need to read it at two in the morning.
• Use the same pattern everywhere. If one name says "temperature", do not call the next one "temp".