SINAMICS V20 High-Speed Spindle: Cn002 Macro Setup Guide

SINAMICS V20 High-Speed Spindle: Cn002 Macro Setup and Minimum-Speed Run Resolution

The Siemens SINAMICS V20 is a compact, stand-alone AC drive commonly paired with high-frequency spindle motors in CNC routers, wood-working machines, and small machining centers. Because the V20 supports analog setpoints up to 400 Hz output frequency, it is one of the few sub-kW class drives capable of driving a 24,000 RPM or 40,000 RPM HF spindle directly without an intermediate frequency converter. However, applying the Cn002 connection macro to a spindle application introduces a specific wiring hazard: if digital input DI1 is left floating or pulled to the wrong rail, the drive will start the spindle at P1080 (minimum frequency) the moment the line contactor closes. This article documents the correct wiring, parameter set, and the root-cause fix for the unintended minimum-speed run condition.

1. Drive Selection and Frame Sizing for High-Speed Spindles

The SINAMICS V20 is offered in 230 V 1AC and 400 V 3AC variants with power ratings from 0.12 kW to 30 kW. High-frequency spindles (typically 100 Hz to 400 Hz base frequency, two-pole or four-pole) are usually supplied as 220 V 3-phase or 380 V 3-phase stator windings. Match the drive as follows:

Confirm the motor nameplate rated current is below the V20's continuous output current for the selected frame. For high-speed spindles, the rated current can be 50% to 100% higher than an equivalent kW-rated 50 Hz motor because of higher iron and copper losses at 400 Hz operation.

Refer to the official SINAMICS V20 Operating Instructions for frame dimensions, overload curves, and derating above 4 kHz switching frequency.

2. Prerequisites

• SINAMICS V20 with firmware version 3.40 or later (earlier versions omit the 400 Hz ceiling parameter path).
• 3AC 380–480 V supply (or 1AC 230 V with derating) wired to L1, L2, L3 (or L, N on 230 V 1AC frames).
• Spindle motor with nameplate data captured: V, A, Hz, RPM, cos φ, insulation class.
• Controller with isolated 0–10 V analog output (≥10 mA drive capability) and a form-C relay contact rated ≥ 50 mA at 24 V DC.
• Siemens V20 BOP (Basic Operator Panel) or Smart Access Module for parameter access.

3. SINAMICS V20 Terminal Layout and Cn002 Macro

The V20 control board exposes the following user-relevant terminals:

Macro Cn002 configures the drive for 2-wire control, one analog setpoint, no direction reversal. After applying the macro, P0701 is forced to 1 (DI1 = ON/OFF1) and P1000 is set to 2 (analog setpoint from AI2). The drive starts as soon as DI1 is driven HIGH and stops as soon as DI1 returns LOW.

4. Target Wiring Topology

4.1 Wiring Diagram (ASCII schematic)

Controller                         SINAMICS V20
(0-10 V source)                   +-----+
+--------+                        |     |
|  AI+   |--- 10V ref (term 2) -->|     |
|  AI-   |--------- 0V (term 5) --|     |
+--------+                        |     |
                                  | V20 |
+--------+                        |     |
| RELAY  |                        |     |
|  COM   |---+--- +24V (term 13)->|     |
|  NO    |   |                    |     |
|  NC    |   +------ DI1 (term 8) |     |
+--------+        \\              |     |
                  (NC closes      +-----+
                   when relay
                   is de-energized)

Jumper: terminal 14 (0V DI) <--> terminal 12 (DIC)

4.2 SVG Topology Diagram

5. Parameter Configuration

Apply the macro first (P0010 = 1, P3900 = 3 with macro parameter; or use BOP macro menu). Then enter the following parameter set, tailored for a 400 Hz / 24,000 RPM HF spindle driven in V/f mode with ramped start:

The published default parameter block from the field report uses P1000 = 7 (analog plus fixed setpoint) rather than the macro default of 2. Keep P1000 = 7 only if you intend to use the fixed setpoint for hand-tuning; otherwise return to P1000 = 2 so the spindle speed follows the 0–10 V command directly.

6. Root Cause: Spindle Rotates at P1080 on Power-Up

The reported symptom – "as soon I turn the inverter on the spindle starts to turn at the minimum speed" – has a single, well-defined root cause: DI1 is in a HIGH state at the moment 24 V is applied to the control board, satisfying the ON/OFF1 condition. The drive then accelerates the motor to the analog setpoint or, if the analog input is near 0 V, the internal setpoint floor P1080 (133 Hz in this case) is applied because of the r0024 smoothing algorithm.

6.1 Why the V20 mis-reads a floating DI1

The V20's digital inputs are non-isolated, sourcing by default (when terminals 12 and 14 are jumpered). Internally, each DI is pulled to +24 V through a ~5 kΩ resistor. If the external contact is an NO relay whose COM is tied to +24 V (terminal 13), then:

• Relay de-energized → NO open → DI1 floats → internal pull-up holds DI1 at +24 V → drive interprets as RUN.
• Relay energized → NO closed → DI1 = +24 V → still RUN (no edge to detect).

There is no OFF transition. The drive therefore runs from the instant the control board powers up, regardless of the controller's intent.

6.2 Verification of the failure mode

1. Disconnect the controller's relay wires from the V20 control terminals.
2. Power the V20 from the line contactor only.
3. Measure terminal 8 (DI1) to terminal 14 (0V) with a DMM set to DC volts.
4. Expected: 0 V to +2 V. If the reading is +18 V to +24 V, the input is floating HIGH – this confirms the failure mode.

7. Corrective Actions (pick one)

7.1 Option A – Re-wire with the NC contact (preferred for safety)

1. Move the relay's COM wire from terminal 13 (+24 V) to terminal 14 (0V).
2. Disconnect the wire from terminal 8 (DI1) and connect it to the relay's NC contact instead of NO.
3. Connect the NO contact to terminal 13 (+24 V) if the controller expects a "run active" feedback voltage.
4. Keep the jumper between terminals 12 and 14.

Result: controller idle → NC closed → DI1 tied to 0V → drive stopped. Controller commands M3 (spindle CW) → relay energizes → NC opens → DI1 floats HIGH → drive runs.

7.2 Option B – Add an external pull-down resistor

1. Install a 3.3 kΩ, 0.25 W resistor between terminal 8 (DI1) and terminal 14 (0V).
2. Keep the existing NO wiring from relay COM (24 V) to NO (DI1).
3. With the relay open, DI1 is now pulled to ~0.7 V (well below the 8 V logic threshold). With the relay closed, DI1 is at 24 V.

7.3 Option C – Reassign the run command to DI2 with macro Cn004

Macro Cn004 swaps the active edge to a 3-wire control pattern. Set P0701 = 0 (DI1 disabled), P0702 = 1 (DI2 = ON/OFF1), and P0703 = 12 (DI3 = OFF2). The 3-wire pattern uses momentary pulses rather than maintained levels, eliminating the floating-input issue. The user must change the controller's relay output from a maintained contact to a momentary start/stop pair.

8. Verification Procedure

1. Re-apply line power with the controller powered but the spindle command at 0% (0 V on AI2).
2. Read r0002 (drive state) on the BOP. It must read Ready (04), not Running (06).
3. Issue a 10% speed command from the controller (1.0 V on AI2).
4. Confirm DI1 is HIGH (LED on BOP for DI1 lit) and r0021 (output frequency) ramps to 40 Hz (10% of 400 Hz) over 3 s.
5. Issue M5 (spindle stop) from the controller. The drive should ramp to 0 Hz over 3 s and return to Ready (04).
6. Disable the controller's 24 V rail. Within 100 ms the relay should drop out and the drive should enter Ready (not coast to stop). Verify with r0002.
7. Run an unloaded 5-minute soak at maximum RPM (10 V → 400 Hz). Monitor r0035 (motor temperature model) and r0026 (DC link voltage). Temperature model should stay below 100% trip threshold; DC link must stay above 380 V DC on a 400 V AC supply.

9. High-Speed Spindle Commissioning Notes

9.1 V/f Voltage Boost at Low RPM

At 400 Hz base frequency the drive's V/f ratio is 220 V / 400 Hz = 0.55 V/Hz. Without compensation, the motor produces very little torque below 50 Hz. Increase P1312 (starting boost) to 25%–40% and verify the motor can hold rated current at 20 Hz. If the spindle stalls under load, switch to P1300 = 2 (V/f with quadratic characteristic) for fans/pumps, or P1300 = 3 (V/f with programmable characteristic) for a custom low-speed torque curve.

9.2 Switching Frequency vs. Spindle Losses

Default switching frequency is 4 kHz. For HF spindles, 8 kHz (P1800 = 8) reduces audible noise and current ripple but increases drive losses by ~30%. The V20 will derate continuous output by 20% at 8 kHz on most frames. For 16 kHz operation, consult the V20 manual's derating curves in section 6.1.

9.3 Bearing Current Mitigation

HF spindles fed by PWM inverters accumulate destructive bearing currents. Install a shaft grounding ring (e.g., AEGIS SGR) on the spindle and verify the V20's output filter (if installed) is the sine-wave type, not the dU/dt type. A common-mode choke (e.g., TDK B82725S2*) on the output side reduces shaft current by 50%–70%.

9.4 Motor Nameplate Data to Capture

10. Fault and Warning Reference (V20 Specific)

11. Spindle-Specific Parameter Audit Checklist

1. P1082 matches the motor's rated frequency (e.g., 400 Hz). The default 50 Hz ceiling will under-utilize the spindle.
2. P2000 (reference frequency) is set equal to P1082 so the analog input scaling P0771 = 21 yields 0–10 V = 0–400 Hz.
3. P1210 = 0 to prevent the drive from auto-restarting after a fault – critical for spindle applications.
4. P1200 = 0 (no flying restart) – the spindle must come to a complete stop before re-energization.
5. P0290 = 0 (reduce PWM on overload) or 1 (reduce output frequency) – protects the drive if the spindle stalls.
6. P0640 (motor overload factor) = 110% to match standard motor thermal models.
7. Verify r0035 (motor temperature model) at steady-state full RPM. It must remain below 100% (warning at 80%, fault at 110%).

12. Troubleshooting Matrix

13. Alternative Macros for CNC Spindle Use

For a CNC controller emitting M-codes through relays, Cn002 with the NC-contact re-wire is the simplest robust pattern. For a controller with separate start/stop pushbuttons, switch to Cn003 and use DI1 (terminal 8) as the stop input (NC pushbutton) and DI2 (terminal 9) as the start input (NO pushbutton).

14. BOP Commissioning Sequence (Quick Reference)

1. Apply 3AC power; the BOP shows READY.
2. Press the green OK button → main menu.
3. Navigate to SETUP → CN002 → YES to load the macro. The drive resets to factory defaults except the macro's pin assignments.
4. Enter motor data: P0304, P0305, P0307, P0310, P0311.
5. Set P0700 = 2, P1000 = 2, P1080 = 133, P1082 = 400, P1120 = 3, P1121 = 3, P1300 = 1, P1312 = 30.
6. Set P2000 = 400, P0770 = 2, P0771 = 21.
7. Set P1210 = 0 (no auto-restart).
8. Press OK to save. The BOP displays BUSY for ~2 s, then returns to READY.
9. Issue a 5 V reference from the controller. The BOP should display the actual frequency, e.g., 200 Hz.
10. Issue M5 and verify the BOP returns to READY with output frequency 0 Hz.