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Actuator / valve (pressure-independent characterised control valve) · Modbus register map
Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU Modbus register map
Updated 28 October 2026
Belimo's electronic pressure-independent valve measures flow with its own sensor and controls either position or flow. On Modbus RTU it takes a relative setpoint and override, and reports position, flow in l/s, gpm and a selectable unit, medium temperature, glycol and accumulated volume, plus fault flags and the min/max flow limits. 32-bit values are low word first.
This page lists 47 Modbus registers for the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU — 18 writable — with the table, 0-based wire address, data type, word order, scale, units and access of each, re-typed from Belimo’s own free documentation (linked below) and checked against it.
- Manufacturer
- Belimo
- Model
- 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU
- Registers
- 47 (18 writable)
- Transport
- Modbus RTU
- Default unit ID
- 1
- Default serial
- 38400 baud, 8N2
- Documented addressing
- 1-based (subtract 1 for the wire address)
- 32-bit word order
- CDAB low word first (word-swapped)
- Firmware
- Version 4 devices (example in the document: 400 = 4.00)
- Also known as
- EP..R2+BAC, EP..R2+KBAC, Electronic pressure-independent valve
Integration notes: Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU
Set address and frame with Belimo Assistant 2, write Setpoint source No. 119 = 1 (Bus), choose Control mode No. 117, then write the setpoint to No. 1 (address 0) and poll flow (No. 8 or 10), position (No. 5) and faults (No. 105).
Minimum registers to map
Addresses are 0-based wire addresses. Enough to monitor and run the unit; map more as the job needs.
| Register | Name | Type | Why | Access |
|---|---|---|---|---|
| HR 118 | Setpoint source | UINT16 | Setpoint source = Bus (default is Analog) | Read/write |
| HR 116 | Control mode | UINT16 | Position or flow control | Read/write |
| HR 0 | Setpoint relative | UINT16 | Setpoint, 0.01 % | Read/write |
| HR 7 | Absolute volumetric flow (l/s) | UINT16 | Flow l/s | Read |
| HR 4 | Relative position | UINT16 | Relative position | Read |
| HR 21 | Temperature flow body (°C) | INT16 | Medium temperature °C | Read |
| HR 104 | Malfunction and service information | BITMAP16 | Fault flags | Read |
| HR 109 | Timeout for communication watchdog | UINT16 | Watchdog timeout | Read/write |
Enable Modbus control & writes
Configure Modbus address (1-247), baud and frame with Belimo Assistant 2, then write No. 119 = 1 so the valve follows the bus setpoint.
Communication loss & watchdog
No. 110 sets the timeout (5-3600 s, default 120 s). If neither No. 1 nor No. 2 is written in that time, the valve performs the Bus fail action in No. 109 (default None) and bit 15 of No. 105 is set.
Byte order & addressing
- Register No. is 1-based; subtract 1 for the wire address.
- Changing Control mode (No. 117) resets the device.
- 32-bit pairs are low word first and must be written with one FC 16 covering only that pair.
Network setup
- Default frame 1-8-N-2 at 38400 baud, address 1.
- Up to 32 nodes per segment without a repeater; terminate with 120 ohm.
Watch out for
- Out of the box the valve listens to the analog input, not the bus.
- 65535 means 'not available'.
Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU Modbus registers
Address = 0-based wire address (the documented number is shown under it when it differs) · Order: ABCD = high word first, CDAB = low word first · Scale: engineering value = raw × scale.
| Table | Address | Name | Description | Type | Order | Scale | Units | Access | Values / bits |
|---|---|---|---|---|---|---|---|---|---|
| HR | 0doc 1 | Setpoint relative | Position or flow setpoint 0-100 %, scaled between the Min and Max limits. | UINT16 | × 0.01 | % | Read/write | ||
| HR | 1doc 2 | Override control | Forces a fixed valve state; min/max follow Control mode. | UINT16 | Read/write | 0 = None; 1 = Open valve; 2 = Close valve; 3 = Minimum flow; 5 = Maximum flow; 6 = Nominal flow; 10 = Motor stop | |||
| HR | 2doc 3 | Command | Service command; returns to 0 after it is sent. | UINT16 | Read/write | 0 = None; 2 = Sync | |||
| HR | 3doc 4 | Device type | UINT16 | Read | 0 = Device not connected; 1 = Air / water; 2 = VAV / EPIV / flow sensor; 3 = Fire; 4 = Energy valve / energy meter; 5 = 6-way EPIV | ||||
| HR | 4doc 5 | Relative position | UINT16 | × 0.01 | % | Read | |||
| HR | 5doc 6 | Absolute position | UINT16 | × 0.01 | ° | Read | |||
| HR | 6doc 7 | Relative volumetric flow | Flow as % of Vmax (No. 107). | UINT16 | × 0.01 | % | Read | ||
| HR | 7doc 8 | Absolute volumetric flow (l/s) | UINT16 | × 0.01 | l/s | Read | |||
| HR | 8doc 9 | Absolute volumetric flow (gpm) | UINT16 | × 0.1 | gpm | Read | |||
| HR | 9doc 10 | Absolute volumetric flow (selected unit) | Unit set by No. 148. | UINT32 | CDAB | × 0.001 | see No. 148 | Read | |
| HR | 11doc 12 | Setpoint analog | Setpoint seen on the analog input when Setpoint source = Analog. | UINT16 | × 0.01 | % | Read | ||
| HR | 12doc 13 | Sensor 1 value | Extra sensor input on Y3; mV for Active, 0/1 for Switch (No. 121). | UINT16 | Read | ||||
| HR | 15doc 16 | Flow setpoint (l/s) | Active absolute flow setpoint. | UINT16 | × 0.01 | l/s | Read | ||
| HR | 16doc 17 | Flow setpoint (gpm) | UINT16 | × 0.1 | gpm | Read | |||
| HR | 17doc 18 | Flow setpoint (selected unit) | Unit set by No. 148. | UINT32 | CDAB | × 0.001 | see No. 148 | Read | |
| HR | 21doc 22 | Temperature flow body (°C) | Medium temperature at the flow sensor. | INT16 | × 0.01 | °C | Read | ||
| HR | 22doc 23 | Temperature flow body (°F) | INT16 | × 0.01 | °F | Read | |||
| HR | 25doc 26 | Glycol concentration | UINT16 | × 0.01 | % | Read | |||
| HR | 59doc 60 | Accumulated volume (m3) | Not resettable. | UINT32 | CDAB | × 0.01 | m3 | Read | |
| HR | 61doc 62 | Accumulated volume (gal) | Not resettable. | UINT32 | CDAB | gal | Read | ||
| HR | 63doc 64 | Accumulated volume (selected unit) | Unit set by No. 150; not resettable. | UINT32 | CDAB | see No. 150 | Read | ||
| HR | 99doc 100 | Bus termination | Shows whether the 120 ohm terminator is enabled (set with Belimo Assistant 2). | UINT16 | Read | 0 = Disabled; 1 = Enabled | |||
| HR | 100doc 101 | Series number 1st part | First block of the serial number on the housing label. | UINT16 | Read | ||||
| HR | 101doc 102 | Series number 2nd part | Second block of the serial number. | UINT16 | Read | ||||
| HR | 102doc 103 | Series number 4th part | Fourth block of the serial number (the third is not exposed). | UINT16 | Read | ||||
| HR | 103doc 104 | Firmware version | Communication module firmware; 400 means version 4.00. | UINT16 | Read | ||||
| HR | 104doc 105 | Malfunction and service information | Bit-coded fault flags; several can be set at once. | BITMAP16 | Read | bit 0 = No communication to actuator; bit 1 = Gear train disengaged; bit 2 = Actuator cannot move; bit 3 = Reverse flow; bit 4 = Flow setpoint not reached (15 min); bit 5 = Flow with closed valve; bit 6 = Actual flow exceeds nominal flow; bit 7 = Flow measurement error; bit 9 = Flow body temperature error; bit 10 = Communication to flow sensor interrupted; bit 11 = Freeze warning; bit 12 = Glycol detected; bit 15 = Bus watchdog triggered | |||
| HR | 105doc 106 | Minimum volumetric flow | Min flow limit as %; 0 disables it. | UINT16 | × 0.01 | % | Read/write | ||
| HR | 106doc 107 | Maximum volumetric flow | Max flow limit, 25-100 % of Vnom; default 100 %. | UINT16 | × 0.01 | % | Read/write | ||
| HR | 108doc 109 | Bus fail action | Action when the bus watchdog expires. | UINT16 | Read/write | 0 = None; 1 = Open; 2 = Close; 3 = Max; 4 = Min; 6 = Stop | |||
| HR | 109doc 110 | Timeout for communication watchdog | 5-3600 s, default 120 s; any missed setpoint/override write triggers No. 109. | UINT16 | s | Read/write | |||
| HR | 110doc 111 | Nominal volumetric flow (l/s) | Vnom of the valve. | UINT16 | × 0.01 | l/s | Read | ||
| HR | 111doc 112 | Nominal volumetric flow (gpm) | UINT16 | × 0.1 | gpm | Read | |||
| HR | 112doc 113 | Nominal volumetric flow (selected unit) | Unit set by No. 148. | UINT32 | CDAB | × 0.001 | see No. 148 | Read | |
| HR | 116doc 117 | Control mode | Position or flow control; changing it resets the device. Default flow. | UINT16 | Read/write | 0 = Position control; 1 = Flow control | |||
| HR | 118doc 119 | Setpoint source | Analog = 0.5-10 V on wire 3; Bus = No. 1. Default Analog. | UINT16 | Read/write | 0 = Analog; 1 = Bus | |||
| HR | 120doc 121 | Sensor 1 type | Extra sensor input; selectable only when Setpoint source = Bus. | UINT16 | Read/write | 0 = None; 1 = Active; 4 = Switch | |||
| HR | 129doc 130 | Minimum flow limit (l/s) | UINT16 | × 0.01 | l/s | Read/write | |||
| HR | 130doc 131 | Minimum flow limit (gpm) | UINT16 | × 0.1 | gpm | Read/write | |||
| HR | 131doc 132 | Minimum flow limit (selected unit) | Unit set by No. 148. | UINT32 | CDAB | × 0.001 | see No. 148 | Read/write | |
| HR | 133doc 134 | Maximum flow limit (l/s) | Values below 25 % of Vnom are raised to 25 %. | UINT16 | × 0.01 | l/s | Read/write | ||
| HR | 134doc 135 | Maximum flow limit (gpm) | UINT16 | × 0.1 | gpm | Read/write | |||
| HR | 135doc 136 | Maximum flow limit (selected unit) | Unit set by No. 148. | UINT32 | CDAB | × 0.001 | see No. 148 | Read/write | |
| HR | 147doc 148 | Unit selection flow | Unit for No. 10, 18, 113, 132 and 136. Default l/h. | UINT16 | Read/write | 0 = m3/s; 1 = m3/h; 2 = l/s; 3 = l/min; 4 = l/h; 5 = gpm; 6 = cfm | |||
| HR | 149doc 150 | Unit selection volume | Unit for No. 64. Default m3. | UINT16 | Read/write | 0 = m3; 1 = Litre; 2 = Gallon; 3 = cf | |||
| HR | 200doc 201 | Flow meter serial number, first digits | Production order number. | UINT32 | CDAB | Read | |||
| HR | 202doc 203 | Flow meter serial number, last digits | Production sequence number. | UINT32 | CDAB | Read |
Notes on this map
- 32-bit values occupy two registers with the low word first (Belimo's worked example: No. 10 = 14551, No. 11 = 19 gives 19 x 65536 + 14551 = 1,259,735), so they are UINT32 with CDAB word order. Write a 32-bit pair with one FC 16 request covering only those two registers.
- Values are unsigned unless Belimo marks them signed (**): the flow-body temperatures (No. 22/23) are signed two's complement and typed INT16.
- The flow-meter serial-number pairs (No. 201/202, 203/204) are marked LowWord/HighWord in the register overview, so they are typed UINT32 low word first.
- Unsupported registers read 65535. Writable registers from No. 101 up are persistent; don't write them cyclically.
- Belimo notes that the HVAC application may clamp values inside the listed ranges depending on the valve size (see the product datasheet).
- Unlike the air/water actuators, Setpoint source (No. 119) defaults to Analog on this valve: write 1 before bus setpoints take effect.
Check it against the live device. A register map tells you what the controller can expose; the unit in front of you may differ by firmware or options. Read a few registers and compare them with the unit’s own display; for a 32-bit value the float and byte-order decoder shows all four word orders at once, so a wrong word order or scale is obvious. New to this? Read what a register map is and why addresses are off by one.
Questions about the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU
What Modbus registers does the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU have?
This map lists 47 registers: 47 holding registers. 18 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.
Are the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU Modbus addresses 0-based or 1-based?
The manufacturer's document numbers registers 1-based (subtract 1 for the wire address). Every address on this page is the 0-based wire address you put in the request; the documented number is shown under it where it differs. 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.
What byte order does the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU use for 32-bit values?
Multi-register values in this map use CDAB (low word first (word-swapped)). Set your client to this order for every 32/64-bit value in the table.
What are the minimum Modbus registers to integrate the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU?
Start with HR 118 Setpoint source (Setpoint source = Bus (default is Analog)); HR 116 Control mode (Position or flow control); HR 0 Setpoint relative (Setpoint, 0.01 %); HR 7 Absolute volumetric flow (l/s) (Flow l/s); HR 4 Relative position (Relative position); HR 21 Temperature flow body (°C) (Medium temperature °C); HR 104 Malfunction and service information (Fault flags); HR 109 Timeout for communication watchdog (Watchdog timeout).
How do I enable Modbus control of the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU?
Configure Modbus address (1-247), baud and frame with Belimo Assistant 2, then write No. 119 = 1 so the valve follows the bus setpoint.
What happens when the Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU loses Modbus communication?
No. 110 sets the timeout (5-3600 s, default 120 s). If neither No. 1 nor No. 2 is written in that time, the valve performs the Bus fail action in No. 109 (default None) and bit 15 of No. 105 is set.
Where is the official Belimo 2-way EPIV DN 15-50 (Version 4.2) Modbus RTU Modbus documentation?
The source is Modbus interface description - 2-way EPIV, DN 15...50 (Version 4.2) (Edition 2025-09 / V4.2), revision 2025-09, published free by Belimo at https://www.belimo.com/mam/general-documents/system_integration/Modbus/belimo_Modbus-Register_2way-EPIV_V4_2_en-gb.pdf.
More Belimo Modbus register maps
- Actuator / valve (6-way pressure-independent change-over valve)
Belimo 6-way EPIV Modbus RTU (EP..R-R6+BAC)
Belimo 6-way EPIV EP..R-R6+BAC on Modbus RTU, per 6-way EPIV Modbus Register en-gb 2024-01 (general notes dated 16.12.2019).
Also known as: EP..R-R6+BAC, 6-way pressure-independent valve - Actuator / valve (damper and valve actuator)
Belimo Air/water actuators with Modbus RTU (..24A-MOD)
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.
Also known as: 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 - Actuator / valve (pressure-independent control valve with energy metering)
Belimo Energy Valve DN 15-50 (Version 4) Modbus RTU / TCP
Belimo Energy Valve Version 4, DN 15-50 (EV..R2+(K)BAC, EV..R2+MID, EV..R3+BAC), per Energy Valve Modbus interface description en-gb 2023-08.
Also known as: EV..R2+BAC, EV..R2+KBAC, EV..R2+MID, EV..R3+BAC, Energy Valve 4
Source: Modbus interface description - 2-way EPIV, DN 15...50 (Version 4.2) · Edition 2025-09 / V4.2 · rev. 2025-09. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.