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Variable frequency drive · Modbus register map
Invertek Drives Optidrive Eco (built-in Modbus RTU) Modbus register map
Updated 24 October 2026
Invertek's HVAC/pump variable frequency drive with Modbus RTU on its built-in RJ45 RS-485 port (the same port also offers BACnet MS/TP). Registers 1-4 take the control word, speed reference and ramp time; registers 6-35 report status, fault code, output values, I/O, energy and run time; and parameters P1-xx to P5-xx sit at register = parameter number (P1-01 = 101). This map covers the control/monitor block and the P1/P5 parameters a Modbus integration needs.
This page lists 27 Modbus registers for the Invertek Drives Optidrive Eco (built-in Modbus RTU) — 16 writable — with the table, 0-based wire address, data type, word order, scale, units and access of each, re-typed from Invertek Drives’s own free documentation (linked below) and checked against it.
- Manufacturer
- Invertek Drives
- Model
- Optidrive Eco (built-in Modbus RTU)
- Equipment type
- Variable frequency drive
- Registers
- 27 (16 writable)
- Transport
- Modbus RTU
- Default unit ID
- 1
- Default serial
- 115200 baud, 8N1
- Documented addressing
- 1-based (subtract 1 for the wire address)
- Also known as
- ODV-3, Optidrive Eco HVAC, Optidrive Eco IP20, Optidrive Eco IP55, Optidrive Eco IP66
- Source document
- Optidrive Eco User Guide · 82-HEMAN-IN V3.13 · rev. 2024-11
Integration notes: Invertek Drives Optidrive Eco (built-in Modbus RTU)
Put the drive in fieldbus control with P1-12 = 4, then write register 1 (control word) and register 2 (speed in 0.1 Hz) and poll registers 6-11 for status, fault code, frequency, current, torque and power. Subtract 1 from every register number the guide prints.
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 0 | Command control word | BITMAP16 | Control word: run/stop, fault reset | Read/write |
| HR 1 | Command speed reference | INT16 | Speed reference, 0.1 Hz | Read/write |
| HR 5 | Error code / drive status | BITMAP16 | Status bits (low byte) + fault code (high byte) | Read |
| HR 6 | Output frequency | INT16 | Output frequency, 0.1 Hz | Read |
| HR 7 | Output current | UINT16 | Output current, 0.1 A | Read |
| HR 9 | Output power | INT16 | Output power, 0.01 kW | Read |
| HR 22 | DC link voltage | UINT16 | DC bus voltage | Read |
| HR 111 | P1-12 Primary command source | UINT16 | P1-12 command source (must be 4) | Read/write |
| HR 33 | Running time - hours | UINT16 | Total run time, hours | Read |
Enable Modbus control & writes
Set P1-14 = 101 to open the extended parameter groups, then set P5-01 node address (1-63; P5-16 for higher addresses), P5-03 baud rate and P5-04 data format, and set P1-12 = 4 (Fieldbus control) so registers 1-2 can run the drive. The hardware ENABLE input must be present before a start command from the fieldbus is accepted. With P1-12 = 6 the port runs BACnet MS/TP instead of Modbus.
Communication loss & watchdog
P5-05 Communications loss timeout (0.0-5.0 s, default 1.0 s, 0 disables) with P5-06 action: 0 trip and coast, 1 ramp then trip, 2 ramp only, 3 run at preset speed 4. A timeout trips fault 50 (Built-in Modbus RTU communication timeout).
Byte order & addressing
- Register numbers in the guide are 1-based: subtract 1 for the wire address (register 1 = address 0, P1-01 = register 101 = address 100).
- Only function codes 03, 06 and 16 are supported, and 16 (write multiple) works for registers 1-4 only - write parameters one at a time with 06.
- Register 6 holds status in the low byte and the fault code in the high byte; mask and shift rather than reading it as one number.
- Fault reset (control word bit 2) must be set back to 0 after the fault clears.
Network setup
- Wire to the RJ45 port: pin 7 = RS485-, pin 8 = RS485+, pin 3 = 0 V common. Connect the 0 V common across all devices; it is not an Ethernet port.
- Use shielded twisted pair (120 ohm), terminate the end of the network with 120 ohm, and ground the shield at the controller only.
- Defaults: address 1 (P5-01), 115.2 kbps (P5-03), no parity / 1 stop bit (P5-04 'n-1'). Baud choices include 9.6, 19.2, 38.4, 57.6, 76.8 and 115.2 kbps.
- P5-15 adds an extra reply delay in characters for slow masters.
Watch out for
- If P1-12 is not 4, writes to registers 1-2 do not control the drive; registers 6-24 can still be read in any mode.
- P1-01/P1-02 change to rpm once P1-10 Motor rated speed is set to the nameplate rpm.
- Register 3 is reserved on the Eco; there is no torque reference register.
- P0-49 counts Modbus RTU communication errors - read it on the keypad when diagnosing a noisy bus.
Invertek Drives Optidrive Eco (built-in 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 | Command control word | Run, fast stop, reset and coast stop bits; needs P1-12 = 4. | BITMAP16 | Read/write | bit 0 = Run/stop: 1 = run (enable), 0 = stop; bit 1 = Fast stop: 1 = stop using the 2nd deceleration ramp; bit 2 = Fault reset: 1 = reset trip; set back to 0 after the fault clears; bit 3 = Coast stop: 1 = coast to stop | |||
| HR | 1doc 2 | Command speed reference | Frequency setpoint in 0.1 Hz (500 = 50.0 Hz); needs P1-12 = 4. | INT16 | × 0.1 | Hz | Read/write | ||
| HR | 3doc 4 | Command ramp times | Accel/decel time 0-60000 = 0.00-600.00 s; used only when P5-07 = 1. | UINT16 | × 0.01 | s | Read/write | ||
| HR | 5doc 6 | Error code / drive status | Low byte = status bits, high byte = fault code when tripped. | BITMAP16 | Read | bit 0 = 1 = running (enabled), 0 = stopped; bit 1 = 1 = tripped, 0 = healthy; bit 2 = 1 = Hand, 0 = Auto; bit 3 = Inhibit; bit 4 = Service due; bit 5 = Standby (sleep) active; bit 6 = Drive ready; bit 7 = 1 = low or high load condition detected; bit 8 = Bits 8-15 (upper byte): fault code number while tripped (50 = Modbus timeout) | |||
| HR | 6doc 7 | Output frequency | 0.1 Hz (123 = 12.3 Hz). | INT16 | × 0.1 | Hz | Read | ||
| HR | 7doc 8 | Output current | 0.1 A (105 = 10.5 A). | UINT16 | × 0.1 | A | Read | ||
| HR | 8doc 9 | Output torque | Motor torque in 0.1 % (474 = 47.4 %). | INT16 | × 0.1 | % | Read | ||
| HR | 9doc 10 | Output power | 0.01 kW (1100 = 11.00 kW). | INT16 | × 0.01 | kW | Read | ||
| HR | 10doc 11 | Digital input status | Bit n = digital input n+1. | BITMAP16 | Read | bit 0 = Digital input 1; bit 1 = Digital input 2; bit 2 = Digital input 3 | |||
| HR | 19doc 20 | Analog input 1 level | Applied signal in 0.1 % (1000 = 100.0 %). | INT16 | × 0.1 | % | Read | ||
| HR | 20doc 21 | Analog input 2 level | Applied signal in 0.1 % (1000 = 100.0 %). | INT16 | × 0.1 | % | Read | ||
| HR | 22doc 23 | DC link voltage | Measured DC bus voltage in whole volts. | UINT16 | V | Read | |||
| HR | 23doc 24 | Drive temperature | Measured heatsink temperature in whole °C. | INT16 | °C | Read | |||
| HR | 33doc 34 | Running time - hours | Total run time, hours part (P0-31). | UINT16 | h | Read | |||
| HR | 100doc 101 (P1-01) | P1-01 Maximum frequency / speed limit | x10 per the guide's example (500 = 50.0 Hz); rpm when P1-10 > 0. | UINT16 | × 0.1 | Hz | Read/write | ||
| HR | 101doc 102 (P1-02) | P1-02 Minimum frequency / speed limit | Same format as P1-01; rpm when P1-10 > 0. | UINT16 | × 0.1 | Hz | Read/write | ||
| HR | 102doc 103 (P1-03) | P1-03 Acceleration ramp time | 0.0-6000.0 s, sent x10 (default 30.0 s). | UINT16 | × 0.1 | s | Read/write | ||
| HR | 103doc 104 (P1-04) | P1-04 Deceleration ramp time | 0.0-6000.0 s, sent x10 (default 30.0 s). | UINT16 | × 0.1 | s | Read/write | ||
| HR | 104doc 105 (P1-05) | P1-05 Stop mode | Action when the enable signal is removed. | UINT16 | Read/write | 0 = Ramp; 1 = Coast; 2 = AC flux braking | |||
| HR | 106doc 107 (P1-07) | P1-07 Motor rated voltage / kE | Motor nameplate voltage (back-EMF for PM motors). | UINT16 | V | Read/write | |||
| HR | 108doc 109 (P1-09) | P1-09 Motor rated frequency | Nameplate frequency, whole Hz (25-500). | UINT16 | Hz | Read/write | |||
| HR | 109doc 110 (P1-10) | P1-10 Motor rated speed | 0 = speeds shown in Hz; nameplate rpm switches to rpm. | UINT16 | rpm | Read/write | |||
| HR | 111doc 112 (P1-12) | P1-12 Primary command source | Set 4 to control the drive over Modbus RTU. | UINT16 | Read/write | 0 = Terminal control; 1 = Keypad control, uni-directional; 2 = Keypad control, uni-directional; 3 = PID control; 4 = Fieldbus control (Modbus RTU or option module; not BACnet); 5 = Slave mode; 6 = BACnet MS/TP mode | |||
| HR | 112doc 113 (P1-13) | P1-13 Digital input function | Digital input macro selection (see guide's P1-13 table). | UINT16 | Read/write | ||||
| HR | 504doc 505 (P5-05) | P5-05 Communications loss timeout | 0.0-5.0 s, sent x10; 0 disables (default 1.0 s). | UINT16 | × 0.1 | s | Read/write | ||
| HR | 505doc 506 (P5-06) | P5-06 Communications loss action | UINT16 | Read/write | 0 = Trip and coast to stop; 1 = Ramp to stop then trip; 2 = Ramp to stop only (no trip); 3 = Run at preset speed 4 | ||||
| HR | 506doc 507 (P5-07) | P5-07 Fieldbus ramp control | 1 = ramp times come from register 4. | UINT16 | Read/write | 0 = Disabled (ramps from P1-03/P1-04); 1 = Enabled (ramps from fieldbus) |
Notes on this map
- Register 6 packs two bytes: the low byte is the 8-bit status word, the high byte the fault code. Read the register, then take (value >> 8) for the fault number; 0 means no fault.
- The guide does not say whether the output values are signed. Frequency, torque, power, analog levels and temperature are typed INT16 here: every value in their documented ranges is below 32768, so INT16 and UINT16 decode identically, and INT16 is also right if the drive sends a negative value.
- Parameter registers follow the guide's rule: register number = parameter number, and a parameter shown with one decimal place is sent x10 (the guide's example: P1-01 = 500 means 50.0 Hz). When P1-10 Motor rated speed is non-zero, P1-01/P1-02 are in rpm instead and the decimal handling for rpm is not stated.
- The guide says P5-01 (drive address), P5-03 (baud rate) and P5-04 (data format) are not accessible over Modbus, so they are not listed; P5-16 (alternative Modbus address) is left out for the same reason.
- The register-4 text says ramp control needs 'P5-08 = 1', but the introduction and the P5-07 parameter description both put Fieldbus Ramp Control in P5-07; this map follows P5-07.
- Left out: register 22 pre-ramp speed reference (units not stated), registers 30-33 kWh/MWh meters (resolution not stated, and the guide labels both the resettable and non-resettable pairs as P0-26/P0-27), register 35 run time minutes and seconds (packing not stated), register 3 (reserved), P1-08 motor current and P1-11 boost (decimal places not stated).
- P1-12 values 1 and 2 are both printed as 'Keypad control - uni-directional' in this guide edition.
- The P5-05 text refers to 'P5-07' for the loss action; the action itself is P5-06.
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 Invertek Drives Optidrive Eco (built-in Modbus RTU)
What Modbus registers does the Invertek Drives Optidrive Eco (built-in Modbus RTU) have?
This map lists 27 registers: 27 holding registers. 16 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.
Are the Invertek Drives Optidrive Eco (built-in 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. The guide numbers registers from 1 and says masters that count from 0 must subtract 1, so register 1 (control word) is wire address 0 and register 6 (status) is address 5. Parameters use register = parameter number (P1-01 = register 101 = address 100; P5-05 = 505 = address 504).
What are the minimum Modbus registers to integrate the Invertek Drives Optidrive Eco (built-in Modbus RTU)?
Start with HR 0 Command control word (Control word: run/stop, fault reset); HR 1 Command speed reference (Speed reference, 0.1 Hz); HR 5 Error code / drive status (Status bits (low byte) + fault code (high byte)); HR 6 Output frequency (Output frequency, 0.1 Hz); HR 7 Output current (Output current, 0.1 A); HR 9 Output power (Output power, 0.01 kW); HR 22 DC link voltage (DC bus voltage); HR 111 P1-12 Primary command source (P1-12 command source (must be 4)); HR 33 Running time - hours (Total run time, hours).
How do I enable Modbus control of the Invertek Drives Optidrive Eco (built-in Modbus RTU)?
Set P1-14 = 101 to open the extended parameter groups, then set P5-01 node address (1-63; P5-16 for higher addresses), P5-03 baud rate and P5-04 data format, and set P1-12 = 4 (Fieldbus control) so registers 1-2 can run the drive. The hardware ENABLE input must be present before a start command from the fieldbus is accepted. With P1-12 = 6 the port runs BACnet MS/TP instead of Modbus.
What happens when the Invertek Drives Optidrive Eco (built-in Modbus RTU) loses Modbus communication?
P5-05 Communications loss timeout (0.0-5.0 s, default 1.0 s, 0 disables) with P5-06 action: 0 trip and coast, 1 ramp then trip, 2 ramp only, 3 run at preset speed 4. A timeout trips fault 50 (Built-in Modbus RTU communication timeout).
Where is the official Invertek Drives Optidrive Eco (built-in Modbus RTU) Modbus documentation?
The source is Optidrive Eco User Guide (82-HEMAN-IN V3.13), revision 2024-11, published free by Invertek Drives at https://admin.invertekdrives.com/assets/56AFAD3C-CE1A-4D9D-A91D-F893F86B59D2/82-HEMAN-IN_V3.13%20Optidrive%20Eco%20User%20Guide.pdf.
More Invertek Drives Modbus register maps
Source: Optidrive Eco User Guide · 82-HEMAN-IN V3.13 · rev. 2024-11. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.