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Variable frequency drive · Modbus register map
Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) Modbus register map
Updated 24 October 2026
Danfoss's general-purpose industrial variable frequency drive family (FC 301, and FC 302 which adds flux control modes), with a built-in RS-485 port that can speak Modbus RTU. Control word, bus reference, status word and main actual value sit at fixed holding registers 50000-50210, and every parameter is a holding register at ten times its parameter number. This map covers the control block, the communication and comm-loss parameters and the main 15-xx/16-xx readouts, including the FC 302 high-resolution torque readouts.
This page lists 62 Modbus registers for the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) — 22 writable — with the table, 0-based wire address, data type, word order, scale, units and access of each, re-typed from Danfoss’s own free documentation (linked below) and checked against it.
- Manufacturer
- Danfoss
- Model
- VLT AutomationDrive FC 301/302 (Modbus RTU)
- Equipment type
- Variable frequency drive
- Registers
- 62 (22 writable)
- Transport
- Modbus RTU
- Default unit ID
- 1
- Default serial
- 8E1
- Documented addressing
- derived from parameter numbers
- 32-bit word order
- ABCD high word first (big-endian)
- Firmware
- Programming data per software 9.5x / 48.96 guide; Modbus mapping per Design Guide MG33BF02 (software 6.72)
- Also known as
- VLT AutomationDrive, FC 301, FC301, FC302, FC-302, FC-301, FC 300
Integration notes: Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU)
Set 8-30 to Modbus RTU and power-cycle, make sure 8-02 points at the FC port and the drive is not in local/Hand control, then write the control word to 50000 and the reference to 50010 and poll 50200/50210. Read readouts from the 16-xx registers at parameter number x 10 (minus 1 on the wire).
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 49999 | Control word (CTW) | BITMAP16 | CTW: start/stop/reset | Read/write |
| HR 50009 | Bus reference (REF) | INT16 | REF: speed reference, 4000h = 100% | Read/write |
| HR 50199 | Status word (STW) | BITMAP16 | STW: ready/running/trip/warning | Read |
| HR 16129 | 16-13 Frequency | UINT16 | 16-13 Frequency, 0.1 Hz | Read |
| HR 16139 | 16-14 Motor current | INT32 ABCD | 16-14 Motor current, 0.01 A | Read |
| HR 16169 | 16-17 Speed [RPM] | INT32 ABCD | 16-17 Speed, RPM | Read |
| HR 16099 | 16-10 Power [kW] | INT32 ABCD | 16-10 Power, 10 W steps (0.01 kW) | Read |
| HR 16899 | 16-90 Alarm Word | UINT32 ABCD | 16-90 Alarm word | Read |
| HR 15019 | 15-02 kWh Counter | UINT32 ABCD | 15-02 kWh counter | Read |
Enable Modbus control & writes
Set 8-30 Protocol = [2] Modbus RTU (effective only after the drive is powered off and on), 8-31 Address (1-247, default 1), 8-32 FC Port Baud Rate and 8-33 Parity/Stop Bits. 8-02 Control Word Source must be [1] FC RS485; 8-01 Control Site picks digital inputs and/or control word; 8-50, 8-53, 8-55 and 8-56 default to Logic OR, which decides how bus bits combine with terminals. STW bit 9 must read 1 (not local) and CTW bit 10 (data valid) must be 1 for the control word to act.
Communication loss & watchdog
8-03 Control Word Timeout Time (0.1-18000 s, 0.1 s units) and 8-04 Control Word Timeout Function (Off, Freeze output, Stop, Jogging, Max. speed, Stop and trip, set-up switching; Qstop and trip on software 48.xx; Trip with MCO 302). A valid control word restarts the timer. 8-05 End-of-Timeout Function (default Resume set-up) and 8-06 Reset Control Word Timeout handle recovery after a set-up-switching timeout.
Byte order & addressing
- Parameter register = parameter number x 10, request address = that minus 1 (16-13 -> 16130 -> address 16129).
- 32-bit values are high word first (ABCD).
- REF/MAV use 4000h = 100% of the 3-02..3-03 reference range, negative values in two's complement.
- CTW bit 10 must be 1 or the whole control word is ignored. Derived from the bit table (no ready-made words are printed): bits 2, 3, 4, 5, 6 and 10 set = 047Ch runs on the ramp; clearing bit 6 (043Ch) ramps to stop; bit 7 resets on its rising edge.
- Uint8 parameters still occupy a full 16-bit register.
Network setup
- RS-485 on control-card terminals 68/69 (the built-in FC port); set the Modbus address 1-247 in 8-31 (default 1).
- 8-33 defaults to even parity, 1 stop bit; baud is chosen in 8-32 (2400-115200).
- 8-35 Minimum Response Delay (1-10000 ms, default 10 ms) can be raised for slow masters or RS-485 converters.
- Array parameters need the index written to holding register 9 before the read or write.
Watch out for
- Parameter writes go to RAM only unless coil 65 is set to 1; RAM-only changes are lost at power-down.
- If a fieldbus option is fitted in slot A the drive sets 8-02 to Option A at first power-up, and Modbus control words on the FC port are then ignored.
- Pressing [Stop/Reset] on the keypad or setting 3-13 Reference Site to Local blocks bus control (STW bit 9 = 0); a Local setting survives power-down.
- Torque readout 16-16 is only 16 bits on FC 301/302; use 16-25 for drives whose torque can exceed 3000 Nm.
Danfoss VLT AutomationDrive FC 301/302 (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 |
|---|---|---|---|---|---|---|---|---|---|
| CO | 64doc 65 | Parameter write control | 0 = parameter writes go to RAM only, 1 = RAM and EEPROM. | BIT | Read/write | 0 = RAM only; 1 = RAM and EEPROM | |||
| HR | 6doc 00007 | Last error code | Last error from the FC data object interface. | UINT16 | Read | ||||
| HR | 8doc 00009 | Parameter index (IND) | Array index used for subsequent array-parameter reads/writes. | UINT16 | Read/write | ||||
| HR | 3019doc 3020 (par. 3-02) | 3-02 Minimum Reference | Lower reference limit in the reference unit. | INT32 | ABCD | × 0.001 | Read/write | ||
| HR | 3029doc 3030 (par. 3-03) | 3-03 Maximum Reference | Reference value that REF 4000h (100%) corresponds to. | INT32 | ABCD | × 0.001 | Read/write | ||
| HR | 3129doc 3130 (par. 3-13) | 3-13 Reference Site | Local/remote reference selection. | UINT16 | Read/write | 0 = Linked to hand/auto; 1 = Remote; 2 = Local; 3 = Linked to H/A MCO (for MCO 305) | |||
| HR | 3409doc 3410 (par. 3-41) | 3-41 Ramp 1 Ramp Up Time | Range 0.01-3600 s. | UINT32 | ABCD | × 0.01 | s | Read/write | |
| HR | 3419doc 3420 (par. 3-42) | 3-42 Ramp 1 Ramp Down Time | Range 0.01-3600 s. | UINT32 | ABCD | × 0.01 | s | Read/write | |
| HR | 4139doc 4140 (par. 4-14) | 4-14 Motor Speed High Limit [Hz] | UINT16 | × 0.1 | Hz | Read/write | |||
| HR | 4179doc 4180 (par. 4-18) | 4-18 Current Limit | UINT32 | ABCD | × 0.1 | % | Read/write | ||
| HR | 4189doc 4190 (par. 4-19) | 4-19 Max Output Frequency | Absolute output frequency ceiling. | UINT16 | × 0.1 | Hz | Read/write | ||
| HR | 8009doc 8010 (par. 8-01) | 8-01 Control Site | Which inputs the drive obeys. | UINT16 | Read/write | 0 = Digital and ctrl.word; 1 = Digital only; 2 = Controlword only | |||
| HR | 8019doc 8020 (par. 8-02) | 8-02 Control Word Source | Port the control word is taken from. | UINT16 | Read/write | 0 = None; 1 = FC RS485; 2 = FC USB; 3 = Option A; 4 = Option B; 5 = Option C0; 6 = Option C1; 30 = External Can; 35 = Option A fast (FC 302 only); 37 = Option C0 fast (FC 302 only) | |||
| HR | 8029doc 8030 (par. 8-03) | 8-03 Control Word Timeout Time | Comm-loss timeout (0.1-18000 s). | UINT32 | ABCD | × 0.1 | s | Read/write | |
| HR | 8039doc 8040 (par. 8-04) | 8-04 Control Word Timeout Function | Action when the timeout expires. | UINT16 | Read/write | 0 = Off; 1 = Freeze output; 2 = Stop; 3 = Jogging; 4 = Max. speed; 5 = Stop and trip; 6 = Qstop and trip (software 48.xx only); 7 = Select setup 1; 8 = Select setup 2; 9 = Select setup 3; 10 = Select setup 4; 26 = Trip (with MCO 302 only) | |||
| HR | 8099doc 8100 (par. 8-10) | 8-10 Control Word Profile | UINT16 | Read/write | 0 = FC profile; 1 = PROFIdrive profile; 3 = FC motion profile (software 48.xx only); 5 = ODVA; 7 = CANopen DSP 402; 8 = MCO; 22 = PROFIdrive v4_2 profile | ||||
| HR | 8299doc 8300 (par. 8-30) | 8-30 Protocol | Takes effect after a power cycle. | UINT16 | Read/write | 0 = FC; 1 = FC MC; 2 = Modbus RTU | |||
| HR | 8309doc 8310 (par. 8-31) | 8-31 Address | Drive address on the FC (RS-485) port. | UINT16 | Read/write | ||||
| HR | 8319doc 8320 (par. 8-32) | 8-32 FC Port Baud Rate | UINT16 | Read/write | 0 = 2400; 1 = 4800; 2 = 9600; 3 = 19200; 4 = 38400; 5 = 57600; 6 = 76800; 7 = 115200 | ||||
| HR | 8329doc 8330 (par. 8-33) | 8-33 Parity/Stop Bits | UINT16 | Read/write | 0 = Even parity, 1 stop bit; 1 = Odd parity, 1 stop bit; 2 = No parity, 1 stop bit; 3 = No parity, 2 stop bits | ||||
| HR | 8349doc 8350 (par. 8-35) | 8-35 Minimum Response Delay | Delay before the drive answers (1-10000 ms). | UINT16 | × 0.001 | s | Read/write | ||
| HR | 14999doc 15000 (par. 15-00) | 15-00 Operating hours | Hours the drive has been powered. | UINT32 | ABCD | h | Read | ||
| HR | 15009doc 15010 (par. 15-01) | 15-01 Running Hours | Hours the motor has run. | UINT32 | ABCD | h | Read | ||
| HR | 15019doc 15020 (par. 15-02) | 15-02 kWh Counter | Motor energy consumption. | UINT32 | ABCD | kWh | Read | ||
| HR | 15029doc 15030 (par. 15-03) | 15-03 Power Up's | Number of power-ups. | UINT32 | ABCD | Read | |||
| HR | 15039doc 15040 (par. 15-04) | 15-04 Over Temp's | Number of drive temperature faults. | UINT16 | Read | ||||
| HR | 15049doc 15050 (par. 15-05) | 15-05 Over Volt's | Number of drive overvoltages. | UINT16 | Read | ||||
| HR | 15999doc 16000 (par. 16-00) | 16-00 Control Word | Control word the drive received (same bits as CTW). | BITMAP16 | Read | bit 0 = Preset reference select LSB; bit 1 = Preset reference select MSB; bit 2 = 0 = DC brake, 1 = ramp; bit 3 = 0 = coast stop, 1 = no coasting; bit 4 = 0 = quick stop, 1 = ramp; bit 5 = 0 = hold (freeze) output frequency, 1 = use ramp; bit 6 = 0 = ramp stop, 1 = start; bit 7 = Reset (on 0->1 edge); bit 8 = 1 = jog; bit 9 = 0 = ramp 1, 1 = ramp 2; bit 10 = 1 = data valid (0 = control word ignored); bit 11 = 1 = relay 01 active (if 5-40 set to CTW bit 11); bit 12 = 1 = relay active if 5-40 is set to CTW bit 12 (table says relay 02, text says relay 04); bit 13 = Set-up select LSB; bit 14 = Set-up select MSB; bit 15 = 1 = reverse | |||
| HR | 16009doc 16010 (par. 16-01) | 16-01 Reference [Unit] | Active reference in the configured reference unit. | INT32 | ABCD | × 0.001 | Read | ||
| HR | 16019doc 16020 (par. 16-02) | 16-02 Reference % | Total reference in percent. | INT16 | × 0.1 | % | Read | ||
| HR | 16029doc 16030 (par. 16-03) | 16-03 Status Word | Drive status word (same bits as STW). | BITMAP16 | Read | bit 0 = Control ready; bit 1 = Drive ready; bit 2 = 1 = enable (0 = coasting); bit 3 = Trip; bit 4 = Error (no trip); bit 5 = Reserved; bit 6 = Triplock; bit 7 = Warning; bit 8 = Speed = reference; bit 9 = 1 = bus control possible (0 = local operation); bit 10 = Frequency within limits; bit 11 = In operation (running); bit 12 = Stopped, auto start (inverter overtemperature); bit 13 = Voltage limit exceeded; bit 14 = Torque/current limit exceeded; bit 15 = Thermal timer exceeded | |||
| HR | 16099doc 16100 (par. 16-10) | 16-10 Power [kW] | Motor power; fieldbus value is in 10 W steps. | INT32 | ABCD | × 0.01 | kW | Read | |
| HR | 16109doc 16110 (par. 16-11) | 16-11 Power [hp] | Motor power in hp. | INT32 | ABCD | × 0.01 | hp | Read | |
| HR | 16119doc 16120 (par. 16-12) | 16-12 Motor Voltage | UINT16 | × 0.1 | V | Read | |||
| HR | 16129doc 16130 (par. 16-13) | 16-13 Frequency | Output frequency. | UINT16 | × 0.1 | Hz | Read | ||
| HR | 16139doc 16140 (par. 16-14) | 16-14 Motor current | INT32 | ABCD | × 0.01 | A | Read | ||
| HR | 16159doc 16160 (par. 16-16) | 16-16 Torque [Nm] | Signed shaft torque. | INT16 | × 0.1 | Nm | Read | ||
| HR | 16169doc 16170 (par. 16-17) | 16-17 Speed [RPM] | INT32 | ABCD | RPM | Read | |||
| HR | 16179doc 16180 (par. 16-18) | 16-18 Motor Thermal | Calculated motor thermal load. | UINT16 | % | Read | |||
| HR | 16209doc 16210 (par. 16-21) | 16-21 Torque [%] High Res. | Torque in percent of nominal, 0.1% resolution. | INT16 | × 0.1 | % | Read | ||
| HR | 16219doc 16220 (par. 16-22) | 16-22 Torque [%] | Torque in percent of nominal, signed. | INT16 | % | Read | |||
| HR | 16249doc 16250 (par. 16-25) | 16-25 Torque [Nm] High | Signed shaft torque, 32-bit range. | INT32 | ABCD | × 0.1 | Nm | Read | |
| HR | 16299doc 16300 (par. 16-30) | 16-30 DC Link Voltage | UINT16 | V | Read | ||||
| HR | 16339doc 16340 (par. 16-34) | 16-34 Heatsink Temp. | UINT16 | °C | Read | ||||
| HR | 16349doc 16350 (par. 16-35) | 16-35 Inverter Thermal | Inverter thermal load. | UINT16 | % | Read | |||
| HR | 16389doc 16390 (par. 16-39) | 16-39 Control Card Temp. | UINT16 | °C | Read | ||||
| HR | 16519doc 16520 (par. 16-52) | 16-52 Feedback [Unit] | Process feedback in the reference/feedback unit. | INT32 | ABCD | × 0.001 | Read | ||
| HR | 16569doc 16570 (par. 16-57) | 16-57 Feedback [RPM] | Motor speed from the feedback source. | INT32 | ABCD | RPM | Read | ||
| HR | 16599doc 16600 (par. 16-60) | 16-60 Digital Input | Digital input states, one bit per terminal. | BITMAP16 | Read | bit 0 = Terminal 33; bit 1 = Terminal 32; bit 2 = Terminal 29; bit 3 = Terminal 27; bit 4 = Terminal 19; bit 5 = Terminal 18; bit 6 = Terminal 37 (Safe Torque Off, inverted: 0 = on); bit 7 = MCB 101 terminal X30/4; bit 8 = MCB 101 terminal X30/3; bit 9 = MCB 101 terminal X30/2 | |||
| HR | 16619doc 16620 (par. 16-62) | 16-62 Analog Input 53 | Actual value at terminal 53 (V or mA per terminal mode). | INT32 | ABCD | × 0.001 | Read | ||
| HR | 16639doc 16640 (par. 16-64) | 16-64 Analog Input 54 | Actual value at terminal 54 (V or mA per terminal mode). | INT32 | ABCD | × 0.001 | Read | ||
| HR | 16649doc 16650 (par. 16-65) | 16-65 Analog Output 42 [mA] | INT16 | × 0.001 | mA | Read | |||
| HR | 16899doc 16900 (par. 16-90) | 16-90 Alarm Word | Active alarms as bit flags (see programming guide). | UINT32 | ABCD | Read | |||
| HR | 16909doc 16910 (par. 16-91) | 16-91 Alarm Word 2 | UINT32 | ABCD | Read | ||||
| HR | 16919doc 16920 (par. 16-92) | 16-92 Warning Word | Active warnings as bit flags. | UINT32 | ABCD | Read | |||
| HR | 16929doc 16930 (par. 16-93) | 16-93 Warning Word 2 | UINT32 | ABCD | Read | ||||
| HR | 16939doc 16940 (par. 16-94) | 16-94 Ext. Status Word | Extended status bit flags. | UINT32 | ABCD | Read | |||
| HR | 16949doc 16950 (par. 16-95) | 16-95 Ext. Status Word 2 | UINT32 | ABCD | Read | ||||
| HR | 49999doc 50000 | Control word (CTW) | FC profile control word (8-10 = FC profile). | BITMAP16 | Read/write | bit 0 = Preset reference select LSB; bit 1 = Preset reference select MSB; bit 2 = 0 = DC brake, 1 = ramp; bit 3 = 0 = coast stop, 1 = no coasting; bit 4 = 0 = quick stop, 1 = ramp; bit 5 = 0 = hold (freeze) output frequency, 1 = use ramp; bit 6 = 0 = ramp stop, 1 = start; bit 7 = Reset (on 0->1 edge); bit 8 = 1 = jog; bit 9 = 0 = ramp 1, 1 = ramp 2; bit 10 = 1 = data valid (0 = control word ignored); bit 11 = 1 = relay 01 active (if 5-40 set to CTW bit 11); bit 12 = 1 = relay active if 5-40 is set to CTW bit 12 (table says relay 02, text says relay 04); bit 13 = Set-up select LSB; bit 14 = Set-up select MSB; bit 15 = 1 = reverse | |||
| HR | 50009doc 50010 | Bus reference (REF) | Signed; 16384 (4000h) = 100% of 3-03 Maximum Reference. | INT16 | Read/write | ||||
| HR | 50199doc 50200 | Status word (STW) | FC profile status word. | BITMAP16 | Read | bit 0 = Control ready; bit 1 = Drive ready; bit 2 = 1 = enable (0 = coasting); bit 3 = Trip; bit 4 = Error (no trip); bit 5 = Reserved; bit 6 = Triplock; bit 7 = Warning; bit 8 = Speed = reference; bit 9 = 1 = bus control possible (0 = local operation); bit 10 = Frequency within limits; bit 11 = In operation (running); bit 12 = Stopped, auto start (inverter overtemperature); bit 13 = Voltage limit exceeded; bit 14 = Torque/current limit exceeded; bit 15 = Thermal timer exceeded | |||
| HR | 50209doc 50210 | Main actual value (MAV) | Actual output; scaled like REF (4000h = 100%). | INT16 | Read |
Notes on this map
- Programming data source: VLT AutomationDrive FC 301/FC 302 Programming Guide, software 9.5x and 48.96, AU275636650261en-003201 (2024.09), https://assets.danfoss.com/documents/431896/AU275636650261en-003201.pdf. Each parameter's conversion index gives the scale: -1 = x0.1, -2 = x0.01, -3 = x0.001, 0 = x1, 1 = x10.
- Indices 67, 74, 75 and 100 have no factor in the current guide or in the design guide's conversion table; the FC 301/302 Programming Guide MG33MP02 (software 8.23/48.33, AU275636650261en-001101, Table 5.2, printed p. 262, https://assets.danfoss.com/documents/271654/AU275636650261en-001101.pdf) gives them 1/60, 3600, 3600000 and 1 relative to SI units, so the transferred integer is already in RPM, hours, kWh and degC (scale 1).
- Word order: the design guide says 32-bit parameters use 2 registers but prints no 32-bit example. Danfoss's Modbus RTU Operating Instructions MG92B102 (https://assets.danfoss.com/documents/latest/271338/AQ361181101347en-000101.pdf), written for the Danfoss FC series as a whole and using the same register scheme as this drive's design guide, maps an Int32/Uint32 as bytes 3-2 in the first register and bytes 1-0 in the second (printed p. 17) and its read example for 3-03 at registers 3030/3031 returns 0016E360h = 1500000 (printed p. 22): high word first (ABCD).
- 16-16 Torque [Nm] is Int16 on FC 301/302 (range -3000..3000 Nm, index -1), unlike FC 102/FC 202 where it is Int32; for larger drives read 16-25 Torque [Nm] High (Int32). The MG33MP02 parameter list agrees.
- 16-10 Power [kW] has conversion index 1 and the guide states its fieldbus value is in 10 W steps with W as the base unit, so raw x 0.01 = kW.
- REF and MAV are signed 16-bit values where 16384 (4000h) = 100%; with 3-00 = [0] Min - Max the range runs from 3-02 (0%) to 3-03 (100%), with [1] -Max - +Max it runs from -3-03 to +3-03. Coils 17-32 carry the same reference (0x0-0xFFFF = -200%..~200%).
- 8-bit parameters (Uint8, e.g. 8-31, 16-18, 16-34) are read and written as one 16-bit register.
- 16-62/16-64 analog inputs are in volts or milliamps depending on the terminal mode; the guide prints no unit for the readout.
- Left out: 16-05 Main Actual Value [%] and 16-15 Frequency [%] (normalised N2 type); 16-23 Motor Shaft Power (index 1, base unit not stated); 16-20 Motor Angle (raw encoder units); 16-50 External Reference (no unit printed); 15-30..15-33 alarm log arrays (need IND); text parameters; MCO/positioning (software 48.xx) groups.
- Alarm/warning/extended status words (16-90..16-95) are listed as raw UINT32; their bit meanings are in the programming guide's troubleshooting tables.
- Coils 1-16 / 17-32 / 33-48 / 49-64 mirror CTW, REF, STW and MAV (output frequency in open loop, feedback in closed loop); only coil 65 (parameter write control) is listed separately.
- The design guide's 3-14 example prints registers 3410/3411 and '11300 = 1113.00'; by the x10 rule 3-14 is 3140/3141, so treat that example as a typo.
- The Modbus mapping comes from the MG33BF02 (2013-12-20) edition of the design guide; the parameter numbers, types and conversion indices it relies on were re-checked in the 9.5x programming guide.
- FC 301 and FC 302 share the programming guide; options marked 'FC 302 only' or 'software 48.xx' are noted in the value lists.
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 Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU)
What Modbus registers does the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) have?
This map lists 62 registers: 1 coil, 61 holding registers. 22 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.
Are the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) Modbus addresses 0-based or 1-based?
The manufacturer's document numbers registers derived from parameter numbers. 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. Registers are printed 1-based (the design guide's own rule: register 40001 is address 0, coil 1 is address 0). A parameter's register number is 10 x its parameter number (3-03 -> 3030, 16-13 -> 16130) and the request carries that number minus 1 (16-13 is read at address 16129). The fixed process registers CTW 50000, REF 50010, STW 50200 and MAV 50210 follow the same minus-1 rule (CTW = address 49999). Coil 65 is address 64.
What byte order does the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) use for 32-bit values?
Multi-register values in this map use ABCD (high word first (big-endian)). Set your client to this order for every 32/64-bit value in the table.
What are the minimum Modbus registers to integrate the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU)?
Start with HR 49999 Control word (CTW) (CTW: start/stop/reset); HR 50009 Bus reference (REF) (REF: speed reference, 4000h = 100%); HR 50199 Status word (STW) (STW: ready/running/trip/warning); HR 16129 16-13 Frequency (16-13 Frequency, 0.1 Hz); HR 16139 16-14 Motor current (16-14 Motor current, 0.01 A); HR 16169 16-17 Speed [RPM] (16-17 Speed, RPM); HR 16099 16-10 Power [kW] (16-10 Power, 10 W steps (0.01 kW)); HR 16899 16-90 Alarm Word (16-90 Alarm word); HR 15019 15-02 kWh Counter (15-02 kWh counter).
How do I enable Modbus control of the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU)?
Set 8-30 Protocol = [2] Modbus RTU (effective only after the drive is powered off and on), 8-31 Address (1-247, default 1), 8-32 FC Port Baud Rate and 8-33 Parity/Stop Bits. 8-02 Control Word Source must be [1] FC RS485; 8-01 Control Site picks digital inputs and/or control word; 8-50, 8-53, 8-55 and 8-56 default to Logic OR, which decides how bus bits combine with terminals. STW bit 9 must read 1 (not local) and CTW bit 10 (data valid) must be 1 for the control word to act.
What happens when the Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) loses Modbus communication?
8-03 Control Word Timeout Time (0.1-18000 s, 0.1 s units) and 8-04 Control Word Timeout Function (Off, Freeze output, Stop, Jogging, Max. speed, Stop and trip, set-up switching; Qstop and trip on software 48.xx; Trip with MCO 302). A valid control word restarts the timer. 8-05 End-of-Timeout Function (default Resume set-up) and 8-06 Reset Control Word Timeout handle recovery after a set-up-switching timeout.
Where is the official Danfoss VLT AutomationDrive FC 301/302 (Modbus RTU) Modbus documentation?
The source is Design Guide VLT AutomationDrive FC 301/302 0.25-75 kW (chapter 12 RS-485 Installation and Set-up, Modbus RTU) (MG33BF02), revision 2013-12-20, published free by Danfoss at https://assets.danfoss.com/documents/272493/AJ286655760917en-000301.pdf.
More Danfoss Modbus register maps
- Variable frequency drive
Danfoss VLT AQUA Drive FC 202 (Modbus RTU)
VLT AQUA Drive FC 202 using the built-in RS-485 (FC) port with 8-30 Protocol = Modbus RTU and the FC control profile; parameter data checked against the software 5.4X programming guide.
Also known as: VLT AQUA Drive, FC202, FC-202, AQUA Drive FC 202 - Variable frequency drive
Danfoss VLT HVAC Drive FC 102 (Modbus RTU)
VLT HVAC Drive FC 102 using the built-in RS-485 (FC) port with 8-30 Protocol = Modbus RTU and the FC control profile; parameter scaling checked against the software 7.61 programming guide.
Also known as: VLT HVAC Drive, FC102, FC-102
Source: Design Guide VLT AutomationDrive FC 301/302 0.25-75 kW (chapter 12 RS-485 Installation and Set-up, Modbus RTU) · MG33BF02 · rev. 2013-12-20. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.