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name: powernet-expert description: Maretron MPower digital switching expertise for marine electrical systems. Use when working with CLMD12/16 load controllers, CKM12 keypads, VMM6 rocker switches, NMEA 2000 switching PGNs (127500-127502), SignalK switch integration, or programming MPower devices with N2KAnalyzer. Covers switch instance/channel mapping, circuit control via SignalK, and digital switching network architecture.

PowerNet Expert

Expertise for Maretron MPower digital switching systems and their integration with SignalK.

Quick Reference

MPower Device Family

Device	Function	Channels	Max Load
CLMD12	12-channel DC load controller	4×5A, 6×10A, 2×12A	75A total
CLMD16	16-channel DC load controller	4×25A, 12×12A	125A total
CKM12	12-button customizable keypad	12 programmable buttons	-
VMM6	6-position rocker switch	6 Contura-style switches	-
CBMD12	Bypass module	Mechanical backup for CLMD12	-

Key NMEA 2000 PGNs

PGN	Name	Direction	Purpose
127500	Load Controller Connection State	TX	Reports channel status
127501	Binary Switch Bank Status	TX	Switch on/off states
127502	Binary Switch Control	RX	Command to change state
127751	DC Voltage/Current	TX	Electrical measurements

Switch Instance/Channel Mapping

NMEA 2000 organizes switches into banks of 28:

Instance	Switch Range	Channels
0	Switches 1-28	1-28
1	Switches 29-56	1-28
2	Switches 57-84	1-28

SignalK Switch Paths

electrical.switches.bank.{instance}.{channel}.state    # Switch state (0/1)
electrical.switches.bank.{instance}.{channel}.meta     # Metadata (name, etc.)

Control Switch via REST API

# Turn on switch (instance 0, channel 5)
curl -X PUT -H "Content-Type: application/json" \
  -d '{"value": 1}' \
  http://signalk-host/signalk/v1/api/vessels/self/electrical/switches/bank/0/5/state

# Turn off
curl -X PUT -H "Content-Type: application/json" \
  -d '{"value": 0}' \
  http://signalk-host/signalk/v1/api/vessels/self/electrical/switches/bank/0/5/state

Recommended SignalK Plugins

Plugin	Purpose
pdjr-skplugin-switchbank	Relay control via PUT requests, metadata injection
signalk-n2k-virtual-switch	Virtual switch emulation, responds to PGN 127502
signalk-to-nmea2000	Send SignalK data back to NMEA 2000 network

Detailed References

• references/devices.md - MPower device specifications and capabilities
• references/pgns.md - NMEA 2000 PGN details and field definitions
• references/switch-mapping.md - Instance/channel conventions and planning
• references/plugins.md - SignalK plugin configuration for MPower
• references/programming.md - N2KAnalyzer workflow and device setup

Network Architecture

PowerNet (digital switching) should be physically separated from NavNet (navigation) to:

• Isolate power distribution from navigation data
• Prevent switching traffic from affecting chart updates
• Allow independent troubleshooting

┌─────────────┐         ┌─────────────┐
│   NavNet    │         │  PowerNet   │
│ (Navigation)│         │  (MPower)   │
└──────┬──────┘         └──────┬──────┘
       │                       │
  Chartplotter            SignalK Server
  Instruments             CLMD12/16
  AIS, Radar              CKM12, VMM6

Key Documentation

Resource	URL
CLMD12 Manual	https://www.maretron.com/support/manuals/CLMD12UM_1.9.html
CLMD16 Manual	https://www.maretron.com/support/manuals/CLMD16UM_1.0.html
MPower Overview	https://www.maretron.com/products/digital-switching-mpower/
switchbank Plugin	https://github.com/pdjr-signalk/pdjr-skplugin-switchbank