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Siemens SINAMICS G120 (CU240B-2 / CU240E-2) Modbus register map

SINAMICS G120 inverter with CU240B-2 or CU240E-2 Control Unit (RS485, Modbus RTU): process data, I/O, converter data, diagnostics, faults and technology controller registers

  • Official
  • 58 registers
  • Modbus RTU
  • Revision 1 · 2026-11-10

Official: Written from the manufacturer's documentation, but not tested on a device yet. Check the map against the manufacturer's documentation before you write to a live device. Tested it? Report a test.

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Communication

Protocol
Modbus RTU
Unit ID
1
Serial
19200 8E1 · 19200 baud, 8 data bits, even parity, 1 stop bit
Byte / word order
ABCD · bytes big-endian, words high first
Addresses
0-based

Connection values are defaults: the device may be configured differently.

Map

Registers
58 holding registers
Groups
9
Revision
1 · 2026-11-10
Added
()
File
maps/siemens/sinamics-g120.mbmap.json · 16 KB · history
SHA-256
57cda9d1b4784bb4664b7479a5c9c036740909c5949757f20b49447afc56a669
Manufacturer
siemens.com

Sources and notes

Source: Siemens, "SINAMICS G120 Inverter with CU240B-2 and CU240E-2 Control Units Operating Instructions", 01/2011, FW 4.4, A5E02299792B AB, section 6.2.3 Communication over Modbus RTU, table 6-30; https://pogoni.etf.bg.ac.rs/PLC_PLUS/Control_Units_CU240B-2_and_CU240E-2_en-US.pdf

  • Set p2030 = 2 (fieldbus protocol Modbus) with the macro P0015 = 21; the address comes from the DIP switches or p2021 (1 to 247, effective after a power cycle), the baud rate from p2020 (factory 19200 bit/s). The Control Unit is a Modbus RTU slave with even parity.
  • Addresses are the manual's register numbers minus 40001 (40100 is address 99). Only function codes 3 (read) and 6 (write single register) are used; reading more than 125 registers or crossing the edge of a register block returns an exception.
  • Valid holding registers run from 40001 to 40522. The manual says 40001-40065 are compatible with the Micromaster MM436 but does not list them, so only 40100 onward is mapped.
  • The process data registers 40100, 40101, 40110 and 40111 are monitored by p2040 (factory 100 ms): the drive raises alarm F1910 (setpoint timeout) if they are not accessed within that time. The p2000 reference speed scales the setpoint and actual value words (0x4000 = 100 %).
  • Written from the manual of the CU240B-2/CU240E-2 for firmware 4.4. The CU230P-2 and later firmware use the same Modbus RTU interface, but their manuals were not checked, so the map may differ from them.
  • The manual lists no register with a fixed value, so the map has no reference values.
  • Written from the manufacturer's manual; not tested on a device.
AreaAddressNameTypeAccessUnitScaleDescription
HR 99 uint16 RW Process data 1: control word 1 (STW1). Start = 0x047F, OFF1 = 0x047E.
HR 100 uint16 RW Process data 2: main setpoint, 0x4000 (16384) = 100 % of the reference speed (p2000).
HR 109 uint16 R Process data 1: status word 1 (ZSW1).
HR 110 uint16 R Process data 2: main actual value, 0x4000 (16384) = 100 % of the reference speed (p2000).
HR 199 uint16 RW p0730, r0747.0. HIGH = 1, LOW = 0.
HR 200 uint16 RW p0731, r0747.1. HIGH = 1, LOW = 0.
HR 201 uint16 RW p0732, r0747.2. HIGH = 1, LOW = 0.
HR 219 int16 R % ×0.01 r0774.0.
HR 220 int16 R % ×0.01 r0774.1.
HR 239 uint16 R r0722.0. HIGH = 1, LOW = 0.
HR 240 uint16 R r0722.1. HIGH = 1, LOW = 0.
HR 241 uint16 R r0722.2. HIGH = 1, LOW = 0.
HR 242 uint16 R r0722.3. HIGH = 1, LOW = 0.
HR 243 uint16 R r0722.4. HIGH = 1, LOW = 0.
HR 244 uint16 R r0722.5. HIGH = 1, LOW = 0.
HR 259 int16 R % ×0.01 r0755[0].
HR 260 int16 R % ×0.01 r0755[1].
HR 261 int16 R % ×0.01 r0755[2].
HR 262 int16 R % ×0.01 r0755[3].
HR 299 uint16 R r0200 (power unit code number).
HR 300 uint16 R ×0.01 r0018. The manual gives the scaling factor as 0.0001 but the range as 0.00 to 327.67; the factor 100 of the V20 table is used here.
HR 319 uint16 R kW ×0.01 r0206.
HR 320 uint16 RW % ×0.1 p0640.
HR 321 uint16 RW s ×0.01 p1120.
HR 322 uint16 RW s ×0.01 p1121.
HR 323 uint16 RW RPM p2000.
HR 339 int16 R RPM r0020.
HR 340 int16 R RPM r0022.
HR 341 int16 R Hz ×0.01 r0024.
HR 342 uint16 R V r0025.
HR 343 uint16 R V r0026.
HR 344 uint16 R A ×0.01 r0027.
HR 345 int16 R Nm ×0.01 r0031.
HR 346 uint16 R kW ×0.01 r0032.
HR 347 uint16 R kWh r0039.
HR 348 uint16 R r0807: HAND / AUTO.
HR 399 uint16 R r0947[0].
HR 400 uint16 R r0947[1].
HR 401 uint16 R r0947[2].
HR 402 uint16 R r0947[3].
HR 403 uint16 R r0947[4].
HR 404 uint16 R r0947[5].
HR 405 uint16 R r0947[6].
HR 406 uint16 R r0947[7].
HR 407 uint16 R r2110[0].
HR 498 uint16 R
HR 499 uint16 RW p2200, r2349.0.
HR 500 int16 RW % ×0.01 p2240.
HR 509 uint16 RW ×0.01 p2265.
HR 510 uint16 RW % ×0.01 p2269.
HR 511 uint16 RW ×0.001 p2280.
HR 512 uint16 RW s p2285.
HR 513 uint16 RW p2274.
HR 514 int16 RW % ×0.01 p2291.
HR 515 int16 RW % ×0.01 p2292.
HR 519 int16 R % ×0.01 r2250.
HR 520 int16 R % ×0.01 r2266.
HR 521 int16 R % ×0.01 r2294.

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