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Electrical & Wiring·Lesson 8 of 34

The Radio, VRM, and Radio Power Module

Understand the VH-109 radio, how it must be powered for 2026, and the supporting VRM and RPM modules.

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The robot radio

The radio is the robot's link to the Driver Station and the field network. Historically FRC used the OpenMesh OM5P-AC (and earlier OM5P-AN), which is now retired. The current radio is the Vivid-Hosting VH-109 (V1.5 is the latest revision). It uses Wi-Fi 6E (802.11ax) to escape the crowded 2.4 GHz band (it can still fall back to 2.4 GHz 802.11b/g/n), is ruggedized for the FRC environment, and includes multiple Ethernet ports (a RIO port plus AUX1/AUX2), so most teams no longer need a separate switch.

Powering the VH-109 (2026 rules)

The VH-109 has a wide input range of 4.5-19VDC (12V nominal) and accepts unfiltered battery voltage. For 2026, rule R616 was rewritten and the VRM and RPM are NO LONGER legal ways to power the radio. Radio power must now come directly from the power distribution device, one or both of:

  1. 12V direct wiring into the radio's 12V Weidmuller input terminals, using 18 AWG or larger wire (per R626), from a 10A-protected non-switchable PDH channel (20/21/22) or a PDP/PDP 2.0 terminal.
  2. Passive PoE on the RIO port - power injected into the Ethernet cable feeding the radio's RIO port using a passive injector / Vivid-Hosting PoE adapter cable, fed from the same PD channel.

Wiring both at once is allowed for redundancy, but Vivid-Hosting requires both inputs to be the same source and voltage. Active PoE injectors are prohibited (R616).

The VRM and RPM are still real devices - just not for the radio

  • The CTRE Voltage Regulator Module (VRM) still provides clean, regulated 12V and 5V outputs for custom circuits and vision cameras. As of 2026 it is no longer a legal radio power source, but it remains useful for cameras and low-noise loads.
  • The REV Radio Power Module (RPM) was a dedicated PoE module for the radio; with the 2026 rule change it is no longer a legal way to power the VH-109. If you are reading older guides, note that the RPM output PoE at ~18VDC, which standard PoE cameras do not tolerate - another reason the simpler direct-from-PD approach is now standard.

Best practice: fewer failure points

Every extra module between the radio and the PD is another point of failure on the field. The 2026 direct-wiring requirement formalizes long-standing advice: keep the radio's power path short and simple.

Sources

Key takeaways

  • The legacy OM5P-AC is retired; the Vivid-Hosting VH-109 (V1.5, Wi-Fi 6E, 4.5-19VDC input) is the current FRC radio.
  • For 2026, R616 removed the VRM and RPM as legal radio power sources - power the radio directly from the PD via 12V wiring (18 AWG+) and/or passive PoE on the RIO port.
  • If wiring both 12V and passive PoE, both inputs must be the same source and voltage; active PoE injectors are prohibited.
  • The VRM (regulated 12V/5V) still serves cameras and custom circuits, but is no longer a legal radio power source.

Go deeper

Lesson quiz

Required

Answer all 3 questions correctly to complete this lesson.

1.What is the primary function of the robot radio in the FRC control system?

2.What does the REV Radio Power Module (RPM) primarily do?

3.What does a Voltage Regulator Module (VRM) provide on a robot?

Answer every question to submit.