{
 "manufacturer": "Belimo",
 "manufacturer_slug": "belimo",
 "model": "Air/water actuators with Modbus RTU (..24A-MOD)",
 "model_slug": "air-water-actuators-mod",
 "short_model": "Belimo -MOD actuators",
 "aliases": [
  "LM24A-MOD",
  "NM24A-MOD",
  "SM24A-MOD",
  "GM24A-MOD",
  "LMC24A-MOD",
  "NMC24A-MOD",
  "NR24A-MOD",
  "LR24A-MOD",
  "NV24A-MOD",
  "NVK24A-MOD",
  "LF24A-MOD",
  "NF24A-MOD",
  "NRF24A-MOD",
  "LRF24A-MOD",
  "LH24A-MOD",
  "SH24A-MOD"
 ],
 "equipment_type": "Actuator / valve (damper and valve actuator)",
 "applies_to": "Belimo ..M(C)24A-MOD, ..R24A-MOD, ..V(K)24A-MOD, ..F24A-MOD, ..RF24A-MOD and ..H24A-MOD air/water actuators, per Modbus interface description edition 2026-05 / V3.08.",
 "summary": "Belimo's standard damper and valve actuators in the -MOD version speak Modbus RTU on RS-485 directly. The map is small and flat: a position setpoint, an override, position feedback and an optional sensor input in registers 1-13, then identity, fault flags, Min/Max limits, the bus watchdog and the setpoint source from register 100 up. Everything is a 16-bit unsigned value.",
 "transport": [
  "RTU"
 ],
 "defaults": {
  "unit_id": 1,
  "baud": 38400,
  "parity": "None",
  "data_bits": 8,
  "stop_bits": 2,
  "tcp_port": null
 },
 "addressing": {
  "convention": "1-based",
  "note": "Belimo prints each register twice: 'No.' counts from 1 and 'Address' from 0, and the documented value here is the No. column. Register No. 1 (setpoint) is wire address 0. Every value sits in one flat table, so holding-register reads (FC 3) and writes (FC 6/16) reach everything; FC 4 input-register reads of the same addresses also work."
 },
 "default_word_order": null,
 "firmware": null,
 "source": {
  "title": "Modbus Interface Description - Air/water actuators (General actuators for air and water)",
  "doc_number": "Edition 2026-05 / V3.08",
  "revision_date": "2026-05",
  "url": "https://www.belimo.com/mam/general-documents/system_integration/Modbus/belimo_Modbus-Register_AirWater_V3_8_en-gb.pdf",
  "pages": "General notes pp. 3-4; register overview p. 5; register descriptions pp. 6-8"
 },
 "notes": [
  "Belimo states that all register values are unsigned 16-bit integers; a register that does not apply to the device or its settings reads 65535.",
  "Sensor 1 value (No. 9) changes meaning with Sensor 1 type (No. 108): mV for Active, ohms for the passive types, 0/1 for Switch (scale 1), and 0.1 °C or 0.1 °F for the PT1000/NI1000/NTC10K2 types. It is listed raw (scale 1); multiply by 0.1 yourself for the temperature types.",
  "Writable registers above No. 100 are stored in non-volatile memory; Belimo says not to write them on a regular basis.",
  "No. 190/191 exist only on electronic fail-safe actuators; other types return 65535.",
  "Registers 7, 8, 10-12 and 111-118 are unused in this actuator range and are not listed.",
  "Read Discrete Inputs (FC 2) can also read the bits of No. 105: start bit address = 104 x 16 = 1664."
 ],
 "registers": [
  {
   "table": "holding_register",
   "address": 0,
   "documented": "1",
   "name": "Setpoint",
   "description": "Position setpoint 0-100 %, scaled between Min (No. 106) and Max (No. 107).",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 1,
   "documented": "2",
   "name": "Override control",
   "description": "Forces a fixed position instead of the setpoint.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "RW",
   "values": {
    "0": "None",
    "1": "Open",
    "2": "Close",
    "3": "Min",
    "4": "Mid",
    "5": "Max",
    "6": "Fast open",
    "7": "Fast close"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 2,
   "documented": "3",
   "name": "Command",
   "description": "Starts a service function; reads back 0 once accepted. 4 clears No. 105.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "RW",
   "values": {
    "0": "None",
    "1": "Adaption",
    "2": "Test",
    "3": "Sync",
    "4": "Reset"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 3,
   "documented": "4",
   "name": "Actuator type",
   "description": "",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": {
    "0": "Actuator not connected",
    "1": "Air / water",
    "2": "VAV / EPIV",
    "3": "Fire",
    "4": "Energy Valve",
    "5": "6-way EPIV"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 4,
   "documented": "5",
   "name": "Relative position",
   "description": "",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 5,
   "documented": "6",
   "name": "Absolute position",
   "description": "Degrees for rotary actuators, mm for linear actuators.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "° / mm",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 8,
   "documented": "9",
   "name": "Sensor 1 value",
   "description": "Raw reading of sensor input 1; meaning and scale follow No. 108 (see notes).",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 12,
   "documented": "13",
   "name": "Analog setpoint",
   "description": "Setpoint seen on the 0-10 V input when Setpoint source = Analog.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 99,
   "documented": "100",
   "name": "Bus termination",
   "description": "Shows whether the built-in 120 ohm terminator is on (set with the tool).",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": {
    "0": "Inactive",
    "1": "Active"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 100,
   "documented": "101",
   "name": "Series number 1st part",
   "description": "First block of the serial number on the housing label.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 101,
   "documented": "102",
   "name": "Series number 2nd part",
   "description": "Second block of the serial number.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 102,
   "documented": "103",
   "name": "Series number 4th part",
   "description": "Fourth block of the serial number (the third is not exposed).",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 103,
   "documented": "104",
   "name": "Firmware version",
   "description": "Bus module firmware; 302 means version 3.02.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 104,
   "documented": "105",
   "name": "Malfunction and service information",
   "description": "Bit-coded fault and status flags; clear with Command = 4.",
   "data_type": "BITMAP16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "R",
   "values": null,
   "bits": {
    "1": "Mechanical travel increased (moved outside adapted range)",
    "2": "Actuator cannot move (overload / blocked)",
    "8": "Internal activity (test run, adaption)",
    "9": "Gear train disengaged (manual override pressed)",
    "10": "Bus watchdog triggered"
   },
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 105,
   "documented": "106",
   "name": "Min",
   "description": "Lower position limit; must stay at least 20 % below Max. Default 0.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 106,
   "documented": "107",
   "name": "Max",
   "description": "Upper position limit; must stay at least 20 % above Min. Default 100 %.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 107,
   "documented": "108",
   "name": "Sensor 1 type",
   "description": "What is wired to sensor input 1; restart may be needed after a change.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "RW",
   "values": {
    "0": "None",
    "1": "Active",
    "2": "Passive_1K",
    "3": "Passive_20K",
    "4": "Switch",
    "5": "PT1000_C",
    "6": "NI1000_C",
    "7": "NTC10K2_C",
    "8": "PT1000_F",
    "9": "NI1000_F",
    "10": "NTC10K2_F"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 108,
   "documented": "109",
   "name": "Bus fail position",
   "description": "Where the actuator goes when the bus watchdog expires.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "RW",
   "values": {
    "0": "None / last setpoint",
    "1": "Fast close",
    "2": "Fast open",
    "3": "Mid position (parametrised)"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 109,
   "documented": "110",
   "name": "Timeout for bus watchdog",
   "description": "0 disables; defaults to 120 s once a bus fail position is set.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "s",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 118,
   "documented": "119",
   "name": "Setpoint source",
   "description": "Bus = No. 1 drives the actuator; Analog = 0-10 V on wire 3. Default Bus.",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "",
   "access": "RW",
   "values": {
    "0": "Analog",
    "1": "Bus"
   },
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 189,
   "documented": "190",
   "name": "Fail-safe bridging time",
   "description": "Delay before the fail-safe move after power loss (electronic fail-safe types only).",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 1,
   "units": "s",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  },
  {
   "table": "holding_register",
   "address": 190,
   "documented": "191",
   "name": "Fail-safe position",
   "description": "Position taken on power loss (electronic fail-safe types; knob on 'Tool').",
   "data_type": "UINT16",
   "length": 1,
   "word_order": null,
   "scale": 0.01,
   "units": "%",
   "access": "RW",
   "values": null,
   "bits": null,
   "offset": 0
  }
 ],
 "integration": {
  "summary": "Wire to the RS-485 terminals, set address and frame with the Belimo Assistant app (or the Address button quick-addressing), then write the position in 0.01 % to register 1 (wire address 0) and poll registers 5 and 105. Leave Setpoint source (No. 119) at Bus, its default.",
  "minimum_registers": [
   {
    "table": "holding_register",
    "address": 0,
    "why": "Position setpoint, 0.01 %"
   },
   {
    "table": "holding_register",
    "address": 1,
    "why": "Override (open/close/min/mid/max)"
   },
   {
    "table": "holding_register",
    "address": 4,
    "why": "Relative position feedback"
   },
   {
    "table": "holding_register",
    "address": 104,
    "why": "Fault and service flags"
   },
   {
    "table": "holding_register",
    "address": 118,
    "why": "Setpoint source must be Bus"
   },
   {
    "table": "holding_register",
    "address": 108,
    "why": "Bus fail position"
   },
   {
    "table": "holding_register",
    "address": 109,
    "why": "Bus watchdog timeout"
   }
  ],
  "enable": "Modbus is active out of the box on -MOD actuators; Setpoint source (No. 119) defaults to Bus. Address (1-247), baud rate and frame are set with the Belimo Assistant 2 app or tool, and the address can also be set with the Address and Adaption buttons (see the product datasheet).",
  "watchdog": "Not monitored by default. Set Bus fail position (No. 109) and Timeout for bus watchdog (No. 110, 0-3600 s; 0 = off, 120 s default once a fail position is set). If neither No. 1 nor No. 2 is written within the timeout, the actuator goes to the fail position and bit 10 of No. 105 is set. In hybrid mode (Setpoint source = Analog) bus monitoring is not active.",
  "quirks": [
   "The No. column is 1-based; subtract 1 for the wire address (setpoint = address 0).",
   "Min and Max must stay at least 20 % apart (Min <= Max - 20 %, Max >= Min + 20 %).",
   "Registers that a device or its settings don't support read 65535."
  ],
  "setup": [
   "Factory frame is 38400 baud, 8 data bits, no parity, 2 stop bits (1-8-N-2), address 1.",
   "Supported frames: 1-8-N-2, 1-8-N-1, 1-8-E-1, 1-8-O-1; baud 9600-115200.",
   "Up to 32 nodes per segment without a repeater; terminate the bus ends with 120 ohm."
  ],
  "gotchas": [
   "Don't write the persistent registers (No. 101 and up) on every poll cycle - they live in non-volatile memory.",
   "Fast open / Fast close overrides add mechanical wear; Belimo suggests keeping them for events like frost protection."
  ]
 },
 "page": "https://easymodbus.com/modbus-register-maps/belimo/air-water-actuators-mod",
 "address_note": "address = 0-based Modbus wire (PDU) address; documented = as printed in the source.",
 "note": "Re-typed from the manufacturer's public documentation (see source) and verified against it. Registers vary by firmware and options; verify against the live device before writing."
}