Configuring BICO on SINAMICS G120 CU240E-2: Setpoint Switching

1. Overview

The SINAMICS G120 modular drive family uses Control Units (CU) to terminate field wiring and execute the open-loop/closed-loop control firmware for the Power Module. The CU240E-2 (article number 6SL3244-0BB12-1BA0) is a "standard" CU with a built-in PROFIBUS interface and a full set of digital and analog I/O. The "E-2" generation replaces the legacy CU240/CU240E and uses the SINAMICS V4.4/V4.7 parameter model — not the MICROMASTER 4 P0701…P9999 style. This is the root cause of the most common BICO configuration error: P0701-P0709 do not exist on the CU240E-2 because parameter access uses the SINAMICS p / r numbering scheme.

This article walks through the BICO configuration required for a frequently-requested application: speed setpoint switching between two analog sources, with DI1 as start command and DI2 as setpoint selector. The procedure uses native SINAMICS parameters and works with the BOP-2 operator panel, STARTER, or TIA Portal (Startdrive).

2. Prerequisites

• Hardware: SINAMICS G120 Power Module (PM240/PM250/PM260) + Control Unit 6SL3244-0BB12-1BA0 (CU240E-2, FW ≥ V4.4). For older FW V4.3 the analog-input scalings (p0756-p0761) have identical semantics.
• Commissioning tool: One of: BOP-2 (basic operator panel), IOP (intelligent operator panel), STARTER V5.x, or TIA Portal V16+ with Startdrive V16+.
• Wiring:
  • AI1 (terminals 3/4): potentiometer 0-10 V (differential). Shielded twisted pair, shield grounded at the CU end.
  • AI2 (terminals 10/11): 4-20 mA current loop from PLC/transmitter. Observe polarity; jumper for current mode if required.
  • DI0 (terminal 5): ON/OFF1 command. Wire the start contact between the 24 V supply and terminal 5.
  • DI1 (terminal 6): setpoint selector. Wire the selection contact between 24 V and terminal 6.
• Access level: p0003 = 3 (Expert) — required to edit BICO parameters.
• Drive state: p0010 = 0 for all online changes unless a commissioning macro is being applied.

3. BICO Concept on SINAMICS G120

BICO ("Binector Connector") is the SINAMICS graphical method for routing a signal from a source to a sink without rewiring. Every CU240E-2 parameter that ends in […] with a "CI/BI" prefix is a sink; every parameter with a "CO/BO" prefix is a source.

Setting a CI/BI parameter to the index of a CO/BO source builds the interconnection. Example: p0840[0] = 722.0 routes the status of DI0 to the ON/OFF1 command sink. The legacy MM4 syntax (P0701 = 1) has no equivalent on the E-2 platform.

4. Hardware Identification: 6SL3244-0BB12-1BA0

The article number 6SL3244-0BB12-1BA0 decodes as follows:

• 6SL3244 — SINAMICS G120 Control Unit family
• 0BB — CU240E-2 (E = extended I/O; "-2" denotes the 2nd generation)
• 1 — version line / firmware class
• BA0 — PROFIBUS interface, no Safety Integrated, no encoder, standard I/O count

Available I/O on this CU:

For full hardware specs refer to the CU240B-2 / CU240E-2 Operating Instructions (BA6) and the CU240B-2 / CU240E-2 List Manual (V4.7/V5.x).

5. Application Requirements

The target function as specified by the field engineer:

• AI1 (variable voltage from potentiometer, 0-10 V) = primary speed setpoint.
• AI2 (4-20 mA from external transmitter/PLC) = alternate speed setpoint.
• DI0 = start command (ON/OFF1, level-triggered).
• DI1 = setpoint selector:
  • DI1 = 0 (low) → speed setpoint sourced from AI1.
  • DI1 = 1 (high) → speed setpoint sourced from AI2.
• Motor must accelerate/decelerate on the ramp set by p1120 / p1121.
• Direction controlled via the setpoint polarity; positive = forward, negative = reverse (when reverse enable is granted).

6. Signal Flow Design

There are two clean ways to switch between two analog setpoints on the CU240E-2:

6.1 Method A — Command Data Set (CDS) switching

The drive supports two Command Data Sets (CDS0 and CDS1). Each CDS has its own copy of p1070[0] (main setpoint), p1071[0] (scaling), p0840[0] (ON/OFF1), and dozens of other command sinks. Toggling a digital input into p0810 (CDS bit 0) selects which CDS is active.

+24 V ---[ DI1 contact ]--- terminal 6
                                  |
                                  v
                             r0722.1 (BO)
                                  |
                          p0810 = 722.1 (BI)
                                  |
                       CDS bit 0 toggles CDS
                                  |
              +-------------------+-------------------+
              |                                       |
        CDS0 active                              CDS1 active
        p1070[0] = 755[0]                       p1070[0] = 755[1]
        (setpoint = AI1)                         (setpoint = AI2)
              |                                       |
              +---------------+-----------------------+
                              v
                       main setpoint path
                              v
                       p1070 -> ramp -> motor

6.2 Method B — Free-function-block (FFB) multiplexer

When a single parameter is needed for HMI display, an FFB MUX block (e.g., p20218 selection switch) routes r0755[0] or r0755[1] to p1070[0]. This is more flexible but requires FFB configuration (Startdrive or expert p20000+ tools).

For this article, Method A (CDS) is the recommended approach because it does not consume free function blocks, keeps the engineering tool simple, and the active CDS is observable at r0050.0 for diagnostics.

7. Parameter Mapping

Analog scaling formulas used in p0756-p0761:

• Voltage input (0-10 V): r0755[0] [%] = (V_AI1 - p0757[0]) / (p0759[0] - p0757[0]) × p0760[0]
• Current input (4-20 mA): r0755[1] [%] = (mA_AI2 - p0757[1]) / (p0759[1] - p0757[1]) × p0760[1]
• With the defaults p0759 = 10 V / 20 mA and p0760 = 100 %, the raw input value in % is forwarded directly to p1070.

8. Step-by-Step Configuration

1. Restore factory defaults (optional, recommended on first commissioning):

   p0010 = 30
   p0970 = 1

   Wait for p0970 = 0 to confirm factory restore completion.
2. Run quick commissioning:

   p0010 = 1
   p0003 = 3
   p0100 = 0   (50 Hz, IEC)
   p0205 = 0   (DC-link voltage selection)
   p0300 = 1   (induction motor)
   p0304 = motor rated voltage
   p0305 = motor rated current
   p0307 = motor rated power
   p0308 = cosPhi
   p0310 = motor rated frequency
   p0311 = motor rated speed
   p0335 = 0   (self-cooled)
   p0700 = 2   (terminals as command source)
   p1000 = 2   (analog setpoint)
   p1080 = 0   (min speed)
   p1082 = max speed
   p1120 = 10  (ramp-up s)
   p1121 = 10  (ramp-down s)
   p1300 = 0   (V/f linear)
   p3900 = 3   (exit quick commissioning with calculation)

3. Configure access level and BICO sinks:

   p0003 = 3
   p0010 = 0
   p0840[0] = 722.0    ; ON/OFF1 from DI0
   p0844[0] = 1        ; no OFF2 (default = ON)
   p0845[0] = 1        ; no OFF3 (default = ON)

4. Configure AI1 (0-10 V from potentiometer):

   p0756[0] = 0        ; unipolar 0-10 V
   p0757[0] = 0        ; x1 = 0 V
   p0758[0] = 0        ; y1 = 0 %
   p0759[0] = 10       ; x2 = 10 V
   p0760[0] = 100      ; y2 = 100 %
   p0761[0] = 0        ; no dead zone

5. Configure AI2 (4-20 mA from PLC/transmitter):

   p0756[1] = 2        ; unipolar 4-20 mA current
   p0757[1] = 4        ; x1 = 4 mA
   p0758[1] = 0        ; y1 = 0 %
   p0759[1] = 20       ; x2 = 20 mA
   p0760[1] = 100      ; y2 = 100 %
   p0761[1] = 1.0      ; 1 mA dead zone (live zero)

6. Wire the setpoint sources — CDS0 (DI1 = 0 → AI1):

   ; switch to CDS0 by writing p0810 = 0, then:
   p1070[0] = 755[0]   ; main setpoint = r0755[0] = AI1

7. Wire the setpoint sources — CDS1 (DI1 = 1 → AI2):

   ; switch to CDS1 by writing p0810 = 1, then:
   p1070[0] = 755[1]   ; main setpoint = r0755[1] = AI2

8. Bind CDS selection to DI1:

   p0810 = 722.1        ; DI1 status drives CDS bit 0

9. Copy CDS0 to CDS1 (bulk, optional):

   p0809[0] = 0
   p0809[1] = 1
   p0809[2] = 1
   p0809[3] = 2

   Then p0809[3] = 2 starts the copy. After completion reset to p0809 = 0.
10. Save to non-volatile memory:

    p0977 = 1

    Wait until the drive returns "SAVE / COMPLETED". A power cycle preserves the changes.

9. Verification

1. DI status: Read r0722. With DI0 = 24 V and DI1 = 0 V the value should be 0000 0001 bin = 1 dec. With DI1 = 24 V the value becomes 0000 0011 bin = 3 dec.
2. Active CDS: Read r0050.0. 0 = CDS0 active, 1 = CDS1 active.
3. Analog raw value: Read r0755[0] (AI1) and r0755[1] (AI2). Move the potentiometer from 0 → 10 V and verify r0755[0] tracks 0 % → 100 %. Inject 4 mA, 12 mA, 20 mA on AI2 and verify r0755[1] reports 0 %, 50 %, 100 %.
4. Setpoint path: With drive stopped (no ON), vary AI1; r0020 (speed setpoint before ramp) should follow. Apply ON (DI0 = 24 V); r0021 (actual speed) ramps to the setpoint.
5. Switching test: Run motor at fixed AI1 setpoint (50 %). Toggle DI1 high (24 V). Setpoint should snap to whatever AI2 currently delivers, with ramp behavior dictated by p1120 / p1121.
6. Edge cases:
   • Open AI2 loop (0 mA) — r0755[1] drops below 0 %. With p0761[1] = 1 mA, values below 1 mA are clamped to 0 %.
   • Disconnect DI1 wire while running — drive remains on last-selected CDS; setpoint does not flap. This is intentional (latched CDS).
   • Toggle DI1 faster than p1120 ramp — drive accelerates/decelerates without overshoot if p1135 (OFF3 ramp) is large enough.

10. Troubleshooting Matrix

11. Alternate Path: TIA Portal / Startdrive

If commissioning from TIA Portal V16 with Startdrive V16:

1. Add the G120 with the CU240E-2 (article 6SL3244-0BB12-1BA0) from the hardware catalog.
2. Open the device view, expand Inputs/Outputs, and click Digital inputs. Confirm DI0 = "ON/OFF1" and DI1 = "CDS bit 0" via the parameter assignment drop-downs.
3. Open Setpoint channel → Main setpoint. For CDS0 select "Analog input 1"; for CDS1 select "Analog input 2".
4. In the Command Data Sets editor, enable CDS1 and assign DI1 to the bit-0 selection.
5. Compile, download, and use the Commissioning panel to verify online values.

Startdrive performs the BICO wiring transparently — the resulting p0810, p1070[0], p0840[0] values match the manual STARTER / BOP-2 procedure above.

12. Field-Proven Caveats

• DI filtering: p0724 applies a debounce time to all DI0-DI5. The default 4 ms is sufficient for relay contacts; for PLC sourcing outputs use 0 ms.
• CDS persistence: CDS selection is volatile by default. To retain the active CDS across power cycles, store it via p0971 = 1 (save parameter set in drive) — the drive powers up in the last-selected CDS only if the related parameters are stored in the user backup; otherwise it defaults to CDS0.
• Loss of CDS select signal: If the DI1 wire breaks, the bit reads 0 and the drive stays in CDS0. Build a fail-safe selection into the wiring: use a normally-closed contact for the "AI2 preferred" mode if needed, combined with an FFB inverter on the BICO output.
• Setpoint ramp interaction: Switching the setpoint source does not affect the active ramp generator. Sudden step changes from 0 % → 100 % between AI1 and AI2 produce ramped output regardless of CDS selection — this is correct behavior.
• Reverse direction: Negative AI1 (only possible if p0756[0] = 1) reverses the drive when p1110 = 0 and reverse is enabled. AI2 in unipolar mode (p0756[1] = 2) cannot produce negative setpoints.

FAQ