# Diamond symbol in schematic

I am having a lot of Diamond symbols in my schematic named as Pxxxx. I am not able to find what it means as there are no legends mentioned in the file.

Also, are there any general conventions that govern the usage of symbols in schematics?

• It's just a net label. – Eugene Sh. Aug 29 '16 at 14:02

Those look to me like testpoints. On an actual board they would either be empty pads or they may actually be testpoint components.

• Are test points typically indicated using this symbol? – Soju T Varghese Aug 29 '16 at 14:08
• As far as I know there is not much of a standard for test points. Usually I see them as little circles with a wire connecting to them (radio-electronics.com/images/…) though using other symbols is not unheard of. It generally comes down to how the design engineer was trained and his/her personal preferences. – DerStrom8 Aug 29 '16 at 14:10
• @SojuTVarghese ours look differently (sort of a triangle) and are labeled TPxx. I guess it's a company wide standard but not much more. – Arsenal Aug 29 '16 at 14:11

I'll hazard a guess that these are test points. These provide an convenient access to a signal. Test points are useful for debugging, quality control testing, calibration, troubleshooting. A signal can be probed at a test point. Or, a test signal may be injected into a test point to exercise the downstream circuitry.

On the PCB, a test point can manifest itself differently, depending on the expected type of test.

• It can be a throughole of surface-mount component for clipping a probe to.
• It can be throughole for sticking an oscilloscope into.
• It can be a surface-mount pad for automated test equipment.

As far as I know, there is no single standard schematic symbol for test points. Here are a few symbols that come with schematic software.

The standard designator for test point it TP (source).