Belimo · HVAC controller
VAV-Compact volumetric flow controller (..MV-D3-MOD, ..HV24A-MOD) Modbus register map
Default configuration
- Protocol
- RS485
- Port
- 502
- Unit ID
- 1
- Addressing
- 0-based
- Byte order
- Big endian
- Word order
- Low word first
- Baud rate
- 38400
- Parity
- None
- Data bits
- 8
- Stop bits
- 2
This device has an RS-485 interface. Reach it through a Modbus RTU-to-TCP gateway, configured with the factory serial settings above.
Register map
| Address | Count | Name | Type | Unit | Scale | Access |
|---|---|---|---|---|---|---|
| 0 | 1 | Setpoint Setpoint related to the position or to the volumetric flow, scaled between Vmin (register 105) and Vmax (register 106). Range 0...10000. Default 0. | UInt16 | % | 0.01 | RW |
| 1 | 1 | Override control 0 = none (default), 1 = open, 2 = close, 3 = min, 4 = mid, 5 = max, 6 = fast open, 7 = fast close. Fast open / fast close cycles increase mechanical load. | UInt16 | - | 1 | RW |
| 2 | 1 | Command 0 = none (default), 1 = adaption, 2 = test, 3 = sync, 4 = reset. After the command is sent the register returns to none; reset clears the malfunction and service information in register 104. | UInt16 | - | 1 | RW |
| 3 | 1 | Actuator type 0 = actuator not connected, 1 = air / water, 2 = VAV / EPIV, 3 = fire, 4 = energy valve, 5 = 6-way EPIV. | UInt16 | - | 1 | R |
| 4 | 1 | Relative position Range 0...10000. | UInt16 | % | 0.01 | R |
| 5 | 1 | Absolute position Degrees for actuators with rotary movement, millimetres for actuators with linear movement (the unit depends on the device). | UInt16 | ° | 1 | R |
| 6 | 1 | Relative volumetric flow Relative volumetric flow of Vnom. Range 0...10000. | UInt16 | % | 0.01 | R |
| 7 | 1 | Absolute volumetric flow Range 0...Vnom. | UInt16 | m3/h | 1 | R |
| 8 | 1 | Sensor 1 value Millivolts if sensor type 1 (register 107) is active, 0 / 1 if sensor type 1 is a switch. Range 0...65535. | UInt16 | mV | 1 | R |
| 10 | 2 | Absolute volumetric flow in the selected unit 32-bit value in the unit chosen by register 117, low word first (the document's own example: address x = low word, x+1 = high word, value = high * 65536 + low). | UInt32 | UnitSel | 0.001 | R |
| 12 | 1 | Analog setpoint Setpoint in percent when the actuator is controlled by the analog signal. | UInt16 | % | 0.01 | R |
| 99 | 1 | Bus termination 0 = inactive (default), 1 = active: the 120 ohm bus termination is enabled. | UInt16 | - | 1 | R |
| 100 | 1 | Series number, 1st part Parts 1, 2 and 4 of the four-part series number are readable; the example 00839-31324-064-008 is read as 00839 / 31324 / 008. | UInt16 | - | 1 | R |
| 101 | 1 | Series number, 2nd part | UInt16 | - | 1 | R |
| 102 | 1 | Series number, 4th part | UInt16 | - | 1 | R |
| 103 | 1 | Firmware version Communication module firmware, e.g. 302 for version 3.02. | UInt16 | - | 1 | R |
| 104 | 1 | Malfunction and service information Bit-coded. Bit 1 mechanical travel increased, bit 2 actuator cannot move, bit 8 internal activity, bit 9 gear train disengaged (manual override pressed), bit 10 bus watchdog triggered. | Binary | - | 1 | R |
| 105 | 1 | Vmin Lower flow limit, range 0...Vmax. Default 0. | UInt16 | % | 0.01 | RW |
| 106 | 1 | Vmax Upper flow limit, range Vmin...10000 and greater than 20 percent. Default 10000. | UInt16 | % | 0.01 | RW |
| 107 | 1 | Sensor 1 type 0 = none (default), 1 = active / hybrid, 4 = switch. Restart the actuator after a change for correct sensor values. | UInt16 | - | 1 | RW |
| 108 | 1 | Bus fail position 0 = none / last setpoint (default), 1 = fast close, 2 = fast open, 3 = mid position. Becomes active when the bus watchdog (register 109) expires. | UInt16 | - | 1 | RW |
| 109 | 1 | Timeout for bus watchdog 0 = deactivated (default), range 0...3600 s. When a bus fail position is configured the document states a default of 120 s. | UInt16 | s | 1 | RW |
| 110 | 1 | Nominal volumetric flow | UInt16 | m3/h | 1 | R |
| 112 | 2 | Nominal volumetric flow in the selected unit Vnom in the unit chosen by register 117, low word first. | UInt32 | UnitSel | 0.001 | R |
| 116 | 1 | Control mode 0 = position control, 1 = flow control. | UInt16 | - | 1 | RW |
| 117 | 1 | Unit selection flow 0 = m3/s, 1 = m3/h (default), 2 = l/s, 3 = l/min, 4 = l/h, 5 = gpm, 6 = cfm. | UInt16 | - | 1 | RW |
| 118 | 1 | Setpoint source 0 = analog signal on wire 3, 1 = bus (default, setpoint from register 0). | UInt16 | - | 1 | RW |
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Related guides
Notes
Source: Belimo 'Modbus Interface Description - VAV-Compact, Volumetric flow compact control device', edition 2026-01 / V3.08, manufacturer date 01.12.2023 (belimo_Modbus-Register_VAV_V3_8_en-gb.pdf), read from Belimo's own regional mirror https://www.belimo.ro/mam/general-documents/system_integration/Modbus/belimo_Modbus-Register_VAV_V3_8_en-gb.pdf because www.belimo.com answers automated requests with HTTP 403; same MAM document and edition, the URL above is the canonical location. Applicable actuator types: ..MV-D3-MOD and ..HV24A-MOD. Factory Modbus settings from the document's 'Modbus RTU' block: 38400 Bd, transmission format 1-8-N-2 (8 data bits, no parity, 2 stop bits), address 1; 9600/19200/76800/115200 Bd and 1-8-N-1 / 1-8-E-1 / 1-8-O-1 are selectable, as are addresses 1...247. Addressing: the document prints both numberings - 'All data is arranged in a table and addressed by 1..n (Register No.) or 0..n-1 (Address)' - and every row carries both columns; the values stored here are the Address column (Register No. minus 1), hence zero_based. Word order: 32-bit values are 'little endian byte swap / LSW (Least Significant Word) first', so the low word sits at the lower Register No. and the two 32-bit rows (10 and 112) are read LowFirst; the document's worked example gives high word 19 at Register No. x+1 and low word 14551 at x, value = 19 * 65536 + 14551. Every value is an unsigned 16-bit integer and the document makes no distinction between data types, so all rows live in holding registers and FC 3/6/16 reach everything (FC 2/4 are alternatives). Left out: registers 9, 11, 111, 114 and 115, printed as '–' (reserved or the second half of a 32-bit pair); register 12 is entered read-only because its description table says R while the overview column shows 'R / W'. Scales are the document's plain multipliers (0.01 percent, 0.001 for the unit-selected 32-bit flows).