Connecting to the Field and FMS

Tether vs. field vs. radio

During development you usually control the robot one of three ways: USB tether to the roboRIO, Ethernet tether , or over the robot radio (Wi-Fi) at your team’s address (10.TE.AM.2 style). At a competition, the Alliance Station provides an Ethernet cable that you plug into your operator console laptop; the field’s FMS then assigns your robot to a station (Red 1, Blue 2, etc.) and takes control of enabling/disabling. (The robot side now uses the Vivid-Hosting VH-109 radio , which replaced the older OpenMesh OM5P radio.)

What FMS changes

Once you connect to FMS, the Driver Station behaves differently (per WPILib docs):

• The Operation tab’s mode/enable controls are replaced by “FMS Connected.” You can no longer enable/disable yourself — only the field does , on the match timer.
• Team station selection is locked to whatever the field assigned.
• Software E-Stop shortcuts are ignored — to emergency-stop on the field you must press the physical Team Station E-Stop button. E-Stopping pulls your robot from the match.
• The DS receives official match data (e.g., game-specific data the field sends each match).

The pre-match connection routine

When you get to the field, the technician/operator should run a tight, repeatable routine:

1. Power on the robot and place it in its starting configuration before connecting.
2. Plug the Alliance Station Ethernet into the laptop; make sure you aren’t simultaneously bridged to robot Wi-Fi in a conflicting way.
3. Watch the Diagnostics tab : confirm Enet Link → Robot Radio → Robot → FMS all go green. Green across the board means you’ll play.
4. Field connection light check at your station, if your event uses one.
5. Tug test the Ethernet so a loose plug doesn’t drop you at the buzzer.
6. Confirm controllers are recognized in the correct USB order with live feedback.

If an indicator stays red, you have seconds to diagnose: a red Enet Link points to the cable, a red Robot Radio points to the radio/power, and a red Robot with a green radio means the roboRIO itself is not answering pings, so check its power, its boot state, and the Ethernet run from the radio. Knowing this map turns panic into a checklist.

After the match

When the match ends, the field disables you. Wait for the all-clear, retrieve the robot per field rules, unplug, and head to the pit — where the turnaround clock (covered in Module 4) immediately starts. The discipline of the same routine every single match is what separates teams that connect reliably from teams that get surprised on the field.

Key takeaways

• At events you connect via the Alliance Station Ethernet; FMS then controls enable/disable on the match clock.
• Under FMS, manual mode controls become “FMS Connected,” station assignment is locked, and software E-Stop is replaced by the physical Team Station E-Stop button.
• Run the same pre-match routine every time and watch Enet Link → Robot Radio → Robot → FMS go green.
• Memorize which red indicator means which fault so you can diagnose no-comms in seconds.

This lesson was adapted from learnfrc.com.