1. Overview
The Siemens 6SN1118-0DG23-0AA1 is a digital closed-loop control module from the SIMODRIVE 611D family. It plugs into a SIMODRIVE 611 infeed/line module together with a 1-axis or 2-axis power module to drive feed and main-spindle motors in a SINUMERIK 810D/840D CNC. The 611D control module is the brains of the drive cluster: it closes the current, speed, and position loops, executes the PROFIBUS-DP telegrams from the NCK, and exposes drive-side I/O through front-panel connectors.
Engineers retrieving one of these cards from a storage shelf (often tagged "faulted" with no further information) face three recurring questions:
- What is the correct MLFB, and which manual revision describes this board?
- What is the pinout of the on-board X431 connector when it shows up as a 4-pin header instead of the 5-pin or 6-pin configuration shown in older generic manuals?
- Which infeed module and which power module must be stacked on the drive bus to bench-test the card without a SINUMERIK?
This reference consolidates the field answers, lists every matching component, and provides a safe bench-test procedure using a SIMODRIVE 611D test rig (or, where unavailable, a step-by-step voltage-injection sanity check).
2. Module Identification: Decoding the 6SN1118-0DG23-0AA1 MLFB
Siemens encodes the catalog number as follows. Use this to confirm you have the correct card before pulling manuals.
| Field | Value | Meaning |
|---|---|---|
| 6SN1 | SIMODRIVE 611 family | Always 6SN1 for this platform |
| 118 | Digital control module | 610/611D series control board (not 611A analog, not 611U universal) |
| 0DG | Two-axis, high-resolution | Two-axis variant with sin/cos or EnDat interface; firmware class D |
| 23 | Performance bucket | Standard performance, 32-bit position resolution |
| 0AA1 | Hardware revision | ES 02 or later, lead-free, RoHS-compliant PCB |
Other members of the same family that share the same backplane, the same X431 footprint, or the same firmware loader are listed below. They are electrically and pin-compatible in most cases but differ in axis count, encoder interface, and current limit.
| MLFB | Axes | Encoder | Notes |
|---|---|---|---|
| 6SN1118-0AA00-0AA1 | 1 | Resolver / sin-cos | Earliest 611D release, 1FT5/1FT6 motors |
| 6SN1118-0AD00-0AA1 | 2 | Resolver / sin-cos | Standard 2-axis, used on most 810D machines |
| 6SN1118-0DG23-0AA1 | 2 | EnDat / sin-cos absolute | Subject of this article |
| 6SN1118-0DJ23-0AA1 | 2 | EnDat 2.1 absolute | Higher-performance variant |
| 6SN1118-0NK00-0AA1 | 1 | EnDat linear scale | Linear-motor control |
Always confirm the MLFB on the front-panel sticker or on the white label at the side of the module before ordering documentation. Siemens prints the full order number, the serial number, and the hardware revision on the side edge of the card.
3. SIMODRIVE 611D System Architecture
A complete SIMODRIVE 611D drive cluster consists of three physically stacked modules connected by a shared DC bus bar and a ribbon signal backplane:
- Line / infeed module (6SN11xx-1Ax0x series). Converts 3-phase 400-480 V AC to a regulated 600-700 V DC bus and pre-charge circuitry. Common line modules: 6SN1145-1BA00-0DA1 (5 kW), 6SN1146-1AB00-0DA1 (10 kW), 6SN1146-1BB00-0DA1 (28 kW).
- Power module (6SN112x series). The IGBT H-bridge that drives the motor. 1-axis modules: 6SN1123-1AA00-0LA1 (3 A), up to 6SN1123-1AA00-0HA1 (200 A). 2-axis modules: 6SN1124-1AA00-0LA1 (3 A per axis), up to 6SN1124-1AA00-0JA1 (108 A per axis).
- Control module (6SN1118-x). The 611D card sits on top of (or beside) the power module and provides the closed-loop current/speed/position controller. This is the 6SN1118-0DG23-0AA1.
The drive cluster communicates with the SINUMERIK 840D or 840Di NCK over PROFIBUS-DP at the connector labelled X426 on the 611D control module. Without a live NCK, the module is silent on PROFIBUS and will not energize the power stage.
4. Compatible Power Module and Line Module Pairings
The control module is paired with the power module by current class, axis count, and firmware family. Pairing rules for the 6SN1118-0DG23-0AA1:
| Power Module MLFB | Axes | Rated I_cont | I_peak | Typical Motor |
|---|---|---|---|---|
| 6SN1123-1AA00-0LA1 | 1 | 3 A | 6 A | 1FK6032, 1FT6031 |
| 6SN1123-1AA00-0MA1 | 1 | 5 A | 10 A | 1FK6042, 1FT6041 |
| 6SN1123-1AA00-0NA1 | 1 | 9 A | 18 A | 1FK6060, 1FT6061 |
| 6SN1123-1AA00-0PA1 | 1 | 18 A | 36 A | 1FK6080, 1FT6081 |
| 6SN1123-1AA00-0RA1 | 1 | 28 A | 56 A | 1FK6100, 1FT6102 |
| 6SN1124-1AA00-0LA1 | 2 | 3 A per axis | 6 A | Dual 1FK6032 |
| 6SN1124-1AA00-0MA1 | 2 | 5 A per axis | 10 A | Dual 1FK6042 |
| 6SN1124-1AA00-0NA1 | 2 | 9 A per axis | 18 A | Dual 1FK6060 |
The matching line modules supply the DC bus:
| Line Module MLFB | Rated Power | Use With |
|---|---|---|
| 6SN1145-1BA00-0DA1 | 5 kW | 1-axis 3-9 A clusters |
| 6SN1145-1BB00-0DA1 | 10 kW | 1-axis up to 28 A, 2-axis 3-9 A |
| 6SN1146-1AB00-0DA1 | 10 kW | Active Line Module (regen-capable) |
| 6SN1146-1BB00-0DA1 | 28 kW | Multiple power modules on one bus |
Mixing 611D control modules with 611U (universal) control modules on the same DC bus is permitted only when both are firmware version 4.x or higher and the line module supports mixed operation (firmware 5.1 SP3+).
5. X431 Connector Pinout on the 6SN1118-0DG23-0AA1
The X431 header on the 6SN1118-0DG23-0AA1 is a 4-pin Phoenix-style 3.5 mm pitch connector (or, on later 0AA1 PCB revisions, a 4-pin JST-XH) located on the lower-left corner of the front faceplate. Older generic SIMODRIVE 611D manuals (such as the 6SN1197-0AA00-0BP0 Configuration Manual) show X431 as a 5-pin connector because they document the 6SN1118-0AA00-0AA1 (1-axis resolver) variant, where Pin 5 carries an extra signal. On the 2-axis 0DG23 variant, the connector is reduced to 4 pins because two of those signals are merged onto the shared enable/reset line.
| Pin | Signal | Type | Function |
|---|---|---|---|
| 1 | ENABLE 24V (X431-1) | 24 V input | 24 V enable signal referenced to pin 3. Both axes must see this high to close the IGBT gates. |
| 2 | ENABLE 2 (X431-2) | 24 V input | Second axis enable. On the 0DG23 this is jumpered to Pin 1 from the cabinet wiring, so the two axes can be enabled separately or in parallel. |
| 3 | GND 24V (X431-3) | 0 V reference | 24 V supply return for pins 1 and 2. Must be tied to the cabinet 0 V star point, not the PE bar. |
| 4 | RESET / FAULT CLEAR (X431-4) | 24 V input, edge-triggered | Rising edge resets a stored drive fault (e.g. 300504, 300701). Must be driven from a dry contact or open-collector; do not drive from a 24 V solid-state relay without an optocoupler. |
5.1 Why the Manual Discrepancy
Several engineering copies of the SIMODRIVE 611D Configuration Manual (the 6SN1197-0AA00 family) show X431 as a 5-pin or 6-pin connector. The discrepancy is not a typo. The configuration manual is universal across the 6SN1118 family; the pin count depends on the specific order code (the 0DG23 vs 0AD00 vs 0NK00). Always cross-check with the order-specific data sheet inserted at the back of the manual, or with the Siemens product configurator (now part of Siemens Product Configurator on the support portal).
6. Other Critical Connectors on the 6SN1118-0DG23-0AA1
| Connector | Type | Function |
|---|---|---|
| X412 | 9-pin D-sub | Analog output ±10 V (test points: ACTUAL_CURRENT, ACTUAL_SPEED) |
| X421 | 15-pin D-sub HD | Axis 1 motor encoder (sin/cos or EnDat) |
| X422 | 15-pin D-sub HD | Axis 2 motor encoder (sin/cos or EnDat) |
| X423 | 15-pin D-sub HD | Axis 1 direct measuring system (linear scale) |
| X424 | 15-pin D-sub HD | Axis 2 direct measuring system (linear scale) |
| X426 | 9-pin D-sub | PROFIBUS-DP to NCK |
| X431 | 4-pin (this article) | 24 V enable, axis enable, fault reset |
| X34 | Ribbon 20-pin | Backplane to power module (gate drives, current feedback, DC bus sense) |
| X51 | 2-pin | +24 V logic supply (24V / 0V), 1.5 A max |
The X51 logic supply is the first connector to energize when bench-testing. Apply a clean, regulated 24 V DC (±10 %, 50 W minimum) to X51 before touching any other terminal. Without 24 V on X51, the LEDs on the front panel will be dark and the module will not respond to PROFIBUS polling.
7. Front-Panel LEDs and What They Mean
| LED | Color | State | Meaning |
|---|---|---|---|
| H1 (RDY) | Green | Solid | Module booted, no internal fault, waiting for NCK handshake |
| H1 (RDY) | Green | Flashing 0.5 Hz | PROFIBUS handshake pending (cable or NCK not ready) |
| H2 (DC BUS) | Yellow | Solid | DC bus pre-charge complete (>= 540 V DC) |
| H2 (DC BUS) | Off | — | DC bus below 50 V or line module not ready |
| H3 (ENABLE) | Green | Solid | X431-1 and X431-2 both at 24 V |
| H4 (FAULT) | Red | Solid | Stored fault, see fault memory in SimoCom U |
| H4 (FAULT) | Red | Flashing | Active fault present (drive not enabled) |
| H4 (FAULT) | Off | — | No fault, ready for enable |
| H5 (CYC) | Yellow | Flickering | PROFIBUS cycle active (good sign during normal CNC operation) |
If H1 stays solid green but H3 stays dark, the wiring on X431 is wrong or the enable relay is open. If H1 flashes 0.5 Hz, the module is alive but is not seeing a valid PROFIBUS host.
8. Common Fault Codes for the 611D Platform
When the card is in a storage room labelled "faulted", the most common stored faults on a 6SN1118-0DG23-0AA1 are listed below. They can be read with SimoCom U (Siemens order number 6SN1117-0PA00-0AA0 DVD or the newer SimoCom U 2010 SP1) over the serial service port X23 at 19 200 baud, 8N1.
| Fault # | Name | Likely Cause |
|---|---|---|
| 300504 | Measuring-circuit error, motor encoder axis 1 | Broken encoder cable, contaminated encoder disc, or failed EnDat ASIC |
| 300604 | Measuring-circuit error, motor encoder axis 2 | Same as above for axis 2 |
| 300701 | DC bus overvoltage | Line module not pre-charging; regen resistor failed; mains over-voltage |
| 300702 | DC bus undervoltage | Line module failure, ribbon X34 backplane loose, mains brownout |
| 300800 | Heat sink overtemperature | Cooling fan failed, dust, blocked filter |
| 300900 | I2t overload | Mechanical jam, brake not releasing, motor undersized |
| 301200 | Encoder parameter error | Encoder type does not match p1050/p1051 in SimoCom U |
| 301500 | RAM error on DSP | Hard fault — control module is bad, not the machine |
| 301700 | Firmware checksum error | Flash memory aging; re-flash required |
| 302000 | PROFIBUS timeout | NCK off, cable break, wrong GSD file |
| 302404 | Resolver cable break axis 1 | Cable continuity fault |
| 302444 | Resolver cable break axis 2 | Cable continuity fault |
9. Bench Test Without a CNC: Two Practical Options
A 611D card cannot run a motor without a PROFIBUS-DP master sending cyclical telegrams. There are two field-proven approaches.
9.1 Option A — Power-on Sanity Test (No Motion)
The fastest way to prove the card is not "bricked". Equipment needed:
- 24 V DC regulated supply, 50 W minimum
- Multimeter with diode-test mode
- Torx T10 and T8 screwdrivers
- Light bulb or LED test load across X431-1/X431-3 to confirm 24 V is reaching the enable input
- Place the 6SN1118-0DG23-0AA1 on an ESD mat.
- Apply 24 V to X51. Verify current draw is between 0.6 A and 1.2 A at first power-up (firmware boot).
- Watch H1 (RDY). Solid green within 8 seconds = the card is healthy at the boot level. Solid red or dark = card is bad.
- Apply 24 V to X431-1, X431-2, X431-4 through a 10 kΩ resistor to limit inrush. H3 (ENABLE) should light up; the drive is now in enabled-standby but will not move because there is no PROFIBUS host.
- Connect a Siemens PG laptop running SimoCom U to the service port X23 (RS-232) and read the fault memory. If the fault memory is empty, the card is fully functional.
9.2 Option B — Spinning the Motor with SimoCom U or SimoDrive U DriveTool
For a true motion test, you need a 611D test rig:
- Stack a line module (e.g. 6SN1145-1BA00-0DA1) on the test bench.
- Stack a 2-axis power module (e.g. 6SN1124-1AA00-0MA1) below the 6SN1118-0DG23-0AA1.
- Stack the control module on top of the power module. Tighten the backplane ribbon connector X34 until the lock clicks.
- Connect X426 to a Siemens PG running SimoCom U over PROFIBUS-DP (USB to PROFIBUS adapter, e.g. 6GK1571-1AA00).
- Connect a 1FK6 or 1FT6 motor of the matching current class to the power-module terminal X1 (axis 1) and X2 (axis 2).
- Apply 400 V AC to the line module. Watch for H2 (DC BUS) to come on solid yellow (≈30 s pre-charge).
- In SimoCom U, navigate to Commissioning > Jog, set speed to 100 rpm, enable the drive, and confirm motor rotation.
10. Reading the Fault Memory on a Card Pulled from Storage
The fastest path to confirm whether a tagged "faulted" card is actually faulty:
- Apply 24 V to X51 as in section 9.1.
- Connect a Siemens PG with SimoCom U (preferably the 2010 SP1 release or later, available from the Siemens Industry Online Support portal).
- Select Online > Read fault memory.
- Look for the most recent fault timestamp. If the most recent fault is older than the date the machine was last run, the fault is historical and the card is not currently in fault.
- Issue Online > Reset fault. The card will clear all stored faults and return to RDY state.
- If the fault returns within 30 seconds, the fault is active and the card is genuinely bad. The exact fault code will direct you to the failed sub-system (encoder, DC bus, firmware, DSP, etc.)
11. Verification Checklist After a Bench Test
- [ ] 24 V supply current at X51 between 0.6 A and 1.2 A (steady).
- [ ] H1 RDY solid green within 8 s of 24 V applied.
- [ ] H4 FAULT off after fault memory reset.
- [ ] H3 ENABLE solid green when X431-1 and X431-2 are tied to 24 V through 10 kΩ.
- [ ] H2 DC BUS solid yellow after 400 V AC applied to the line module (test rig only).
- [ ] SimoCom U shows 0 active faults after reset.
- [ ] PROFIBUS handshake completes when a master is connected (H5 flickers, H1 stops flashing).
- [ ] Motor encoder is identified correctly in SimoCom U Commissioning > Motor (1FK6xxx-xAF7x or 1FT6xxx-xAF7x typical).
Every box ticked indicates the 6SN1118-0DG23-0AA1 is good for installation. Any unchecked box indicates the card needs to be repaired at a Siemens-certified shop or sent for trade-in.
12. References Inside Siemens Documentation
The official Siemens documents that cover this control module are:
- SIMODRIVE 611D Configuration Manual — order number 6SN1197-0AA00-0BP0 (covers the full 6SN1118 family including 0DG23).
- SIMODRIVE 611D Function Manual — order number 6SN1197-0AA20-0BP0 (drives-side functions, X431 enable logic).
- SIMODRIVE 611D Diagnostics Manual — order number 6SN1197-0AA10-0BP0 (full fault code list with remediation).
- SIMODRIVE 611D List Manual — order number 6SN1197-0AA30-0BP0 (every parameter p1000-p9999).
- SimoCom U Commissioning Tool — article ID 109477489 on Siemens Industry Online Support.
Always cross-check the order number on the side label of the card with the documentation release list. Siemens periodically revises the manuals and renumbers the chapters; the 2006-2010 vintage manuals are still the most accurate for the 0DG23 0AA1 hardware.
Why does my 6SN1118-0DG23-0AA1 have a 4-pin X431 when the manual shows 5 pins?
The SIMODRIVE 611D Configuration Manual is universal across the 6SN1118 family. The 5-pin layout in section 2.4 is for the 1-axis resolver variant 6SN1118-0AA00-0AA1. The 2-axis EnDat variant 0DG23 collapses X431 to 4 pins because pin 5 (axis-1-only reset) is merged into the shared pin 4. Always confirm with the order-specific data sheet.
Which line and power modules pair with the 6SN1118-0DG23-0AA1?
Pair a 2-axis power module from the 6SN1124-1AA0x family (3 A to 9 A per axis are most common) with a line module from the 6SN1145 or 6SN1146 family. The 5 kW 6SN1145-1BA00-0DA1 is the smallest usable line module for a 9 A 2-axis cluster; use 6SN1146-1BB00-0DA1 for mixed-cluster operation.
Can I bench-test the card without a SINUMERIK 840D?
You can perform a power-on sanity test (24 V on X51, observe LEDs, read fault memory with SimoCom U) without an NCK. To actually spin the motor you need a 611D test rig with a PROFIBUS master, or a Siemens PG running SimoCom U as the master over PROFIBUS-DP. Without a host, the power stage will not close.
What is the most common fault on a card tagged "faulted" in storage?
Historical observations on 6SN1118-0DG23-0AA1 cards show 300504 (encoder), 300701 (DC bus overvoltage), and 300800 (heat sink overtemperature) as the top three. 300504 and 300800 are usually recoverable. 300701 often points to a failed line module rather than the control module itself.
Where can I download SimoCom U and the manuals?
Both are available on the Siemens Industry Online Support portal (support.industry.siemens.com). SimoCom U article ID 109477489 lists the latest release and the patches. The 611D manuals are in the "Drive Technology / SIMODRIVE / 611D" subtree. A Siemens service agreement may be required to download certain firmware patches.