• Connectors
• * Female 3-pin socket for cable to RoboRIO
• * Male 3-pin header to connect to switch, device, or sensor.
• Yellow LED indicates that power is present on the DIO cable. This is an instance of a Basic LED circuit
• Red LED lights when the signal is “low”, perhaps because it has been connected to ground by a switch or sensor. This is a slight variant on the Basic LED circuit

Not on the prototype, but hinted on the schematic: additional male headers. The break-beam sensor needs two things wired up: the source and the detector. Sometimes we won't install the actual headers, but will just solder individual wires into the holes - but we can still use the same fabricated board blank.

Before reading this section and studying the DIO tester schematic, you might want to review:

• the Basic LED circuit
• Introduction to Electrical Schematics

The schematic and board files for our design is in our github

We used this DIO tester design to start learning about how to do schematics and board designs; our printed circuit boards pages use this design as an illustration.

Here's a screen shot of the complete schematic:

On the schematic are:

• a basic LED circuit that lights up yellow if the +5v power is present and connected.
• a slightly modified LED circuit that lights a red LED if the signal wire is LOW (connected to ground)
• Four connectors: one socket for connecting to the RoboRio, and three headers for sensors.

We followed the steps in our kicad pcb layout to design the copper traces on the board.

Our first order of 6 boards was done at oshpark. The project is here: https://oshpark.com/shared_projects/UVZvYEPw

We're expecting them back in early December 2018.