Hello,
I build a schematic where i use the "power port " to represent my 5V input but after when i run cvpcb it doesn’t appear so i can associate it to actual power input (this kind of power input,Btw i don’t know what is the name of this thing and how to find it on kicad footprint list ). i also have the same issue with the GND because i also use a power port but after in the actual pcb i need to link it to my power input GND.
That connector on the image is for wiring, not for inserting into a pcb. It gets attached to some panel and then wired to the pcb. Parts like these are not found in a footprint library.
These things are also available for use with pcbs.
You could create your own footprint using ‘wiring holes’ (or just place some wiring holes in the layout).
Look at the sample files from KiCad about Arduino Uno.
The use a solder style connector like this on the arduino.
I think that socket is called a ‘barrel jack’, usually specified by ‘the outer diameter of the jack’ x ‘the outer diameter of the pin’.
You could still use that socket for soldering into a pcb, but the holes that these ‘pins’ need will be pretty big and will give you a hard time. You could opt for oval through holes in the custom footprint to alleviate this and make it more successful, but plated oval through holes aren’t liked or even allowed by the cheaper fab houses you’re likely going to use.
For footprint search for BARELL_JACK in Connect.pretty. Symbol with the same name is in the Eeschema libraries too.
Thanks a lot for all your input,if i understand correctly using a BAREEL_JACK on a pcb is not the best idea,so what kind of connector will be appropriate for my 5V power input ? ( sorry for all my silly question i am really beginner but eager to learn)
Use the connector/socket which is the best for your wall adaptor or power supply unit. Mini jack, barrel jack, Micro USB, banana plug, etc. Everything wil be appropriate. Many cell phone chargers use Micro USB and supplying 5V. So, maybe this is the right way…
I usually use these:
Simple hole in some panel, 2 wires and the pcb somewhere erver where there is some place to fix it.
Most power adaptors can be connected to this one.
There is also one like these available for pcbs.
Failsafe, no shorting of the power adapter when inserting the connector.
Micro USB is a nice little thing, but if you look at it from a false angle, it gets broken.
Yes! A major part of engineering design work is the process of evaluating the good and bad points of possible alternatives.
In 2016, barrel connectors are used as low-voltage power connections in MANY common products - look around you A generation or two ago we may have used RCA plugs, DIN-connectors, XLR-style connectors, or a host of semi-proprietary connectors. A generation from now we will probably use something else.
There are no actual standards telling us how to use barrel connectors, but some combinations of inner diameter, outer diameter, and polarity seem to be more common for some supply voltages than for other voltages. You may want to make your product compatible with power supplies, chargers, or backup battery packs that your customers already use. Or, you may want to select a combination that makes it difficult to connect your product to an incompatible power source.
One example of a 2.1mmx5.5mm power jack, that is intended for soldering onto a printed wiring board, can be found at http://www.cui.com/product/resource/pj-102ah.pdf
Dale
It’s good advice to use the outer barrel as ground (internal pin positive) in case the connector ever manages to get somewhere where there is ground touchable with the bare outer barrel - a current will flow with all sorts of implications and problems (greetings from Murphy).
I’m sure that guy who invented the 2.1mm plug will end up in hell.
Together with some supply chain managers who think that 0.4mm do not matter.
Haha, wait till the USB-C gains wide following. there will be special circle in hell for the inventor 
We should not frighten Vincent about electronics. If he wouldn’t be far away I could give him some training. Did that some time ago for my kid’s school.
I’m working as a product engeneer (NOT production engeneer !!) since 1978.Hardware and Software, MIL, Aerospace and Automotive mostly. Believe me , I’ve seen it all.
We could open a new topic about “What you should avoid”, but that’s a bit off KiCad.
Oh, not long ago I bought a programmer. Delivered with 2.5mm at the power plug and 2.1mm at the programmer itself.
Thanks dwk51,appreciate for all answer and insight
