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Variable frequency drive · Modbus register map
Invertek Drives Optidrive P2 (built-in Modbus RTU) Modbus register map
Updated 24 October 2026
Invertek's high-performance general purpose variable frequency drive, with Modbus RTU on the built-in RJ45 RS-485 port. Registers 1-4 take the control word, speed and torque references and ramp time; registers 6-24 report status, fault code, output values and I/O; 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 25 Modbus registers for the Invertek Drives Optidrive P2 (built-in Modbus RTU) — 15 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 P2 (built-in Modbus RTU)
- Equipment type
- Variable frequency drive
- Registers
- 25 (15 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
- ODP-2, Optidrive P2 IP20, Optidrive P2 IP55, Optidrive P2 IP66
- Source document
- Optidrive P2 User Guide · 82-P2MAN-IN V3.10 · rev. 2024-05
Integration notes: Invertek Drives Optidrive P2 (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 | UINT16 | Output power, 0.01 kW | Read |
| HR 22 | DC bus voltage | UINT16 | DC bus voltage | Read |
| HR 111 | P1-12 Primary command source | UINT16 | P1-12 command source (must be 4) | Read/write |
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 mode) so registers 1-2 can run the drive. In P1-12 = 4, digital input 1 must be closed to allow operation. If a fieldbus option module is fitted in the option slot, the built-in Modbus RTU and CAN ports are disabled.
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 8. A timeout trips fault 50 (Modbus comms fault).
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 range 9.6-115.2 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 4 ramp times are ignored unless P5-07 Fieldbus ramp control = 1; otherwise P1-03/P1-04 apply.
- P0-49 counts Modbus RTU communication errors - read it on the keypad when diagnosing a noisy bus.
Invertek Drives Optidrive P2 (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 | 2doc 3 | Command torque reference | Torque setpoint/limit in 0.1 % (2000 = 200.0 %). | INT16 | × 0.1 | % | 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 3 = 1 = inhibit (STO input open), 0 = ready (STO closed); bit 4 = 1 = maintenance time reached; bit 5 = 1 = standby (sleep) mode active; bit 6 = 1 = ready: mains on, no inhibit, no trip, enable input present; bit 8 = Bits 8-15 (upper byte): fault code number while tripped (50 = Modbus comms fault) | |||
| 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). | UINT16 | × 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 bus 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 | 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 | 104doc 105 (P1-05) | P1-05 Stop mode | Action when the enable signal is removed. | UINT16 | Read/write | 0 = Ramp; 1 = Coast; 2 = Ramp, brake chopper enabled; 3 = Coast, brake chopper enabled; 4 = 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 (10-500). | 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, bi-directional; 3 = PID control; 4 = Fieldbus mode (Modbus RTU when no option module fitted); 5 = Slave mode; 6 = CANopen 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 8 | ||||
| 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 Modbus table does not say whether the output values are signed. Output power is typed UINT16 because the guide's CANopen mapping of the same value (object 200Fh) is Unsigned 16, and a 250 kW drive in overload can pass 327.67 kW. Frequency, torque, analog levels and temperature are typed INT16, matching the guide's Integer 16 CANopen objects for speed, torque and drive temperature; analog input 1 can be set to -10 to +10 V, so its level can go negative.
- 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), P1-03/P1-04 ramp times (resolution is 0.01 s on frame sizes 2-3 but 0.1 s on sizes 4-7, so the Modbus scale depends on the frame), P1-08 motor current and P1-11 boost (decimal places not stated).
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 P2 (built-in Modbus RTU)
What Modbus registers does the Invertek Drives Optidrive P2 (built-in Modbus RTU) have?
This map lists 25 registers: 25 holding registers. 15 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.
Are the Invertek Drives Optidrive P2 (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 P2 (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 bus voltage (DC bus voltage); HR 111 P1-12 Primary command source (P1-12 command source (must be 4)).
How do I enable Modbus control of the Invertek Drives Optidrive P2 (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 mode) so registers 1-2 can run the drive. In P1-12 = 4, digital input 1 must be closed to allow operation. If a fieldbus option module is fitted in the option slot, the built-in Modbus RTU and CAN ports are disabled.
What happens when the Invertek Drives Optidrive P2 (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 8. A timeout trips fault 50 (Modbus comms fault).
Where is the official Invertek Drives Optidrive P2 (built-in Modbus RTU) Modbus documentation?
The source is Optidrive P2 User Guide (82-P2MAN-IN V3.10), revision 2024-05, published free by Invertek Drives at https://admin.invertekdrives.com/assets/6AA7F3D2-B563-4DF8-9821-31C506074AA9/(82-P2MAN-IN)%20P2%20User%20Guide%20V3.10.pdf.
More Invertek Drives Modbus register maps
Source: Optidrive P2 User Guide · 82-P2MAN-IN V3.10 · rev. 2024-05. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.