PCB Ruler - PCB Reference Scale - 15cm Audio Fully Compliant with USB Specification

Fully Compliant with USB Specification v2

and then they can connect to any RS-232 devices

you can either connect your 5V pin or 3

1 x 74LS138 - 3 to 8 Decoder De-Multiplexer IC

PCB Ruler - PCB Reference Scale - 15cm Audio Fully Compliant with USB SpecificationAlthough almost all the PCB design is done on the Computer Simulation Software and almost all the footprints of components are available on it and we dont have to worry about the spacing problems at all. But, if you are working on a project you will notice that there are many instances when you are required to change the design on physical system and then you wont have time to pull out schematic and Gerber files and then this PCB Ruler comes in handy.