1. Home
2. Modbus register maps
3. Boilers & water heaters

Equipment type

Boilers & water heaters Modbus register maps

Updated 29 October 2026

5 boilers & water heaters register maps from 3 manufacturers: AERCO, Buderus, Lochinvar.

• Boiler / water heater controller

  AERCO C-More Boiler Controller (Benchmark / KC series)

  AERCO C-More boiler controllers (software 2.00 or later) used on Benchmark and KC Series boilers and water heaters, as a Modbus RTU slave.

  57 registers · 34 writable · RTU
  Also known as: C-More, Benchmark, KC1000, KC Series, Benchmark boiler, Benchmark water heater
• Boiler / heating system controller

  Buderus Logamatic 5000 boiler and system controller (Modbus TCP, datapoint list 4.0)

  Buderus Logamatic 5313 and 5311 (and the Bosch Control 8313/8311 equivalents) acting as master, firmware 1.3 or later with the 4.0 datapoint list; addresses for slave controllers differ.

  109 registers · 26 writable · TCP
  Also known as: Logamatic 5313, Logamatic 5311, Bosch Control 8313, Bosch Control 8311, Control 8000, BCT 531, Logamatic 5000 Modbus
• Boiler

  Buderus SSB condensing boilers (built-in Modbus RTU)

  Buderus SSB series condensing boilers (Bosch Thermotechnology, North America) using the Modbus terminals on the boiler's internal terminal strip, per installation instructions 6720818450 (2015/10).

  50 registers · 10 writable · RTU
  Also known as: SSB, Buderus SSB boiler, Bosch SSB, 6720818450
• Boiler

  Lochinvar Crest / Crest with Hellcat boilers (ModBus communication board)

  Lochinvar Crest FB/OF 751-6001 and FCB1000-6000 (including Crest with Hellcat) with the ModBus communication board.

  62 registers · 9 writable · RTU
  Also known as: Crest, Crest FB751-6001, Crest OF751-6001, Crest FCB1000-6000, Hellcat, MTR-01
• Boiler / water heater

  Lochinvar Knight / Armor / Wall Mount boilers (ModBus communication board)

  Knight 81-286, Knight XL 400-1000, Armor 151-1000, Outdoor Knight/Knight XL/Armor, AQUAS 400-801, FTXL 400-1000, Wall Mount 51-211, Wall Hung 55-399, Wall Mount Armor 125-200 and Shield 125-500 with the Lochinvar ModBus communication board.

  43 registers · 11 writable · RTU
  Also known as: Knight, Knight XL, Outdoor Knight, Outdoor Knight XL, Armor, Outdoor Armor, Wall Mount Armor, Knight Wall Mount, Knight Wall Hung, AQUAS, FTXL, Shield

Boilers & water heaters: default communication settings

Factory defaults as the manufacturer documents them. Change one setting at a time on site and write down what you changed. Word order applies to 32-bit values; the addressing column says how the manufacturer prints register numbers (every map on this site also gives the 0-based wire address).