verified connector library

Danfoss VLT FC-301/FC-302 drive

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire. Word order and scaling are confirmed at the hardware-verified rung and at no rung below it.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

pointaddress (0-based)typescaleunit
power_kw16100U32BE0.01
power_hp16110U32BE0.01
motor_voltage16120U160.1
frequency16130U160.1
motor_current16140U32BE0.01
frequency_pct16150I160.1
torque16160I160.1
speed_rpm16170U32BE1
motor_thermal16180U161
dc_link_voltage16300U161
heatsink_temp16340U161
inverter_thermal16350U161
control_card_temp16390U161
external_reference16500I160.1
feedback16520U32BE0.001

link settings as documented (unverified): RTU; default 9600 8E1; unit ID 1; Supports Modbus RTU protocol on the RS485 standard bus interface. Parity and stop bits are configurable via parameter 8-33.

bench facts as documented (unverified)
terminals68 (P RS485), 69 (N RS485), 61 (COM RS485)
terminationSwitch S801 (ON=Terminated, OFF=Open)
wiring notesDo not connect cable shield to terminal 61.
response timeout10001 ms
inter-frame delay25 ms
protocol notesMinimum response delay is configurable via parameter 8-35 (default 10 ms). Maximum response delay is configurable via parameter 8-36 (default 10001 ms). Maximum inter-character delay is configurable via parameter 8-37 (default 25 ms).
model register15-40
serial register15-51
firmware register15-43
power3 Phase power input (91 L1, 92 L2, 93 L3)
environmentHeatsink Temp cutout limit is 95 ±5 °C (203 ±9 °F); cutting back in occurs at 70 ±5 °C (203 ±9 °F)
doc revision01/2018
firmware applicabilityControl card MK I: 7.62, 48.2X; Control card MK II: 8.10

⚠ disputed: Heatsink Temp cutout limit is 95 ±5 °C (203 ±9 °F); cutting back in occurs at 70 ±5 °C (203 ±9 °F) — disputed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22) which states that cutting back in occurs at 70 ± 5 °C (which is 158 ± 9 °F, not 203 ± 9 °F) [7.4.3]

⚠ disputed: Do not connect cable shield to terminal 61. — disputed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22) which recommends grounding the cable screen via terminal 61 (which is connected to the frame via an RC link) to avoid potential equalizing currents, or omitting it, but does not forbid it

⚠ disputed: Register map summary (name @ 0-based address): power_kw @ 16100, power_hp @ 16110, motor_voltage @ 16120, frequency @ 16130, motor_current @ 16140, frequency_pct @ 16150, torque @ 16160, speed_rpm @ 16170, motor_thermal @ 16180, dc_link_voltage @ 16300, heatsink_temp @ 16340, inverter_thermal @ 16350, control_card_temp @ 16390, external_reference @ 16500, feedback @ 16520 — disputed by Danfoss FC102/FC302 Modbus Register Overview which shows that the actual 0-based Modbus addresses are off-by-one (e.g., power_kw is at 16099, power_hp is at 16109, etc.) because the parameter number * 10 represents the 1-based register address

field reports — community-sourced, unverified (checked 2026-06-11)
  • 32-bit parameters (such as Reference, Setpoint, etc.) have an inverse word order (swapped word order) when read/written via Modbus RTU, which causes issues when integrating with PLCs like Siemens S7-1200 that expect standard big-endian word order. [source]
  • RS485 wire polarity reversal can cause the drive to return zero values instead of throwing a communication error, which is a common field issue. [source]
  • When using the MCA122 Modbus TCP option card, the Control Word (CTW) register address is 2809 (0-based) or 2810 (1-based) rather than the standard fieldbus CTW registers. [source]
  • confirmed: Supports Modbus RTU protocol on the RS485 standard bus interface. Parity and stop bits are configurable via parameter 8-33. — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22) [8.4.2]
  • confirmed: Control card MK I: 7.62, 48.2X; Control card MK II: 8.10 — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)
  • confirmed: terminals: 68 (P RS485), 69 (N RS485), 61 (COM RS485) — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)
  • confirmed: Switch S801 (ON=Terminated, OFF=Open) — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)
  • confirmed: 3 Phase power input (91 L1, 92 L2, 93 L3) — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)
  • confirmed: Minimum response delay is configurable via parameter 8-35 (default 10 ms). Maximum response delay is configurable via parameter 8-36 (default 10001 ms). Maximum inter-character delay is configurable via parameter 8-37 (default 25 ms). — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)
  • confirmed: identification: firmware_register: 15-43, model_register: 15-40, serial_register: 15-51 — confirmed by Programming Guide VLT AutomationDrive FC 301/302 (MG33MO22)

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

If your device isn't here, upload its register map. Generation is free, and the connector keeps the rung it earns under testing.

To prove a connector against your own device, order hardware verification. If it doesn't verify, you don't pay.

Platform builders can license the verified library: machine-readable maps, the firmware matrix, API access.