Commissioning SINAMICS S120 EPOS Without STARTER via BOP20

Overview of EPOS on SINAMICS S120

The SINAMICS S120 drive platform supports an integrated EPOS (Easy Positioning) basic positioner that turns a servo drive into a self-contained point-to-point positioning axis without an external motion controller. EPOS runs inside the Control Unit (CU320-2 or CU310-2) and exposes a standardized parameter set (p26xx, p25xx, p25xx) for traversing blocks, jog, homing, and direct setpoint input.

Standard commissioning relies on the STARTER / Startdrive tool, which presents the function modules graphically. When STARTER is unavailable (commissioning laptops restricted, drive already in production, headless cabinet, or scripted batch rollout), the BOP20 (Basic Operator Panel 20) or an uploadable script can perform the same parameter changes through the operator panel keypad or through parameter write services. The procedure below achieves a closed-loop servo drive with the basic positioner enabled using only the BOP20 and the parameter list manual.

Prerequisites and Hardware Requirements

Before touching the BOP20 keypad, verify the following:

• Control Unit: SINAMICS S120 with CU310-2 PN/DP or CU320-2. EPOS is firmware-activated on these units; on CU310-2 the function module must be enabled (see r0108 below).
• Power Module: Single-axis AC drive (e.g., PM340 blocksize or Smart Line Module + Motor Module) sized to the motor continuous current.
• Motor: Siemens Drive-CLiQ-equipped servo motor (1FK7, 1FT7, 1PH8, SIMOTICS S-1FK2/S-1FT2). Drive-CLiQ delivers automatic electronic nameplate detection; without Drive-CLiQ you must manually enter motor parameters from p0300…p035x.
• Encoder: Either built-in Drive-CLiQ encoder, or an SMC/SME module plus an external encoder on the motor.
• BOP20: The 6-button panel (order number 6SL3055-0AA00-4BA0). The older BOP (without the trailing "20") does not support the navigation needed for p0108 indexing.
• Firmware: SINAMICS S120 firmware V4.x or V5.x. The r0108 function module framework is consistent across both lines.
• Reference documentation: Current List Manual (LH1) and Commissioning Manual (IH1) for the firmware version on the drive. The SINAMICS S120 Commissioning Manual IH1_112009 shows the BOP20 quick-commissioning workflow with EPOS as a target application.

Understanding the Function Module Architecture (p0108 / r0108)

Function modules on the SINAMICS S120 are activated through the bit-coded parameter p0108. Two indices exist:

• p0108[0] – Currently active function module configuration (read-only equivalent is r0108).
• p0108[1] – Requested / required configuration. Writing here triggers a reconfiguration cycle on the next ramp-up / reset.

The status word r0108 reports the active bits:

For EPOS on a Drive-CLiQ servo, the working value observed in field commissioning is:

p0108[1] = 0x011C (hex) = 0001 0001 1100 (binary)

Decoded: bits 2, 3, 4, and 8 set. Bit 3 enables the basic positioner, bit 4 enables the extended setpoint channel needed by EPOS setpoint sources, bit 8 enables additional EPOS features (positioning / modulo / relative moves) depending on firmware. This matches the field-tested p108 index 1 = 11C noted in the field report. Because the source documents only r0108.3 and r0108.4 as the user-visible indicators, the precise meaning of every bit should be cross-checked against the function diagram in the List Manual for the exact firmware build loaded.

Drive-CLiQ Motor Auto-Identification Sequence

Before touching EPOS parameters, complete motor commissioning. Drive-CLiQ motors stream their electronic nameplate into the drive at power-up; you only need to confirm and run identification.

1. Wire the motor through Drive-CLiQ to the corresponding Motor Module port (X202 on PM340 blocksize, X200 on booksize).
2. Power up the Control Unit. The BOP20 first shows the firmware version, then the drive name.
3. Navigate to p0300 (motor code number for Siemens motors). If Drive-CLiQ detected the motor, p0300 is pre-filled with a numeric code (e.g., 1FK7060-2AF71). Confirm by pressing P.
4. Navigate to p0301 (motor code number / selection list entry). Leave at 0 for Drive-CLiQ auto.
5. Navigate to p0400 (encoder type) and verify the encoder SSID is read from Drive-CLiQ. For absolute encoders ensure p0407[0] = 12 or the value listed for your motor's encoder (24-bit singleturn, 12-bit multiturn combination is typical for 1FK7).
6. Execute p1900 = 1 (motor data identification routine). The drive must be in commissioning mode; ON/OFF1 may need to be held off. The motor will move briefly during this routine; ensure the mechanical axis is free to rotate a few revolutions or inhibit mechanical movement per application rules.
7. Run p1910 = 1 (motor data identification – extended) for saturation characteristic capture if your application requires high torque accuracy.
8. Save parameters with p0977 = 1 (start RAM-to-ROM copy) or hold the Fn + P buttons on the BOP20 to save.

Control Structure Selection: Servo Mode and Closed-Loop Speed Control

EPOS sits on top of closed-loop speed control, which sits on top of the current controller. Confirm the structure before activating the positioner:

• p0099 = 1 – Reserved for firmware cross-check; not strictly required but ensures all dependent parameters are visible.
• p1300 = 21 – Closed-loop speed control with torque limiting (servo mode). Other values (20, 22, 23) are valid for specific servo tuning topologies; 21 is the default for EPOS.
• p1500[0] = 0 – Setpoint source for speed controller is the analog / fieldbus input. For EPOS, switch to p1500[0] = 0 with the speed setpoint coming through the EPOS ramp generator.
• p1501[0] = 0 – Sign-of-life from the positioner.
• p1503[0] = r1114 – Speed setpoint source after ramp-function generator.

Verify the speed controller tuning: p1460 (P-gain), p1462 (integral time). With Drive-CLiQ motors, the auto-tuned defaults from p1900 are normally adequate; capture the closed-loop response with STARTER if oscillation is observed, since BOP20 cannot run a trace.

BOP20 Navigation and Parameter Entry

The BOP20 has six keys: ON (green), OFF (red), Fn (function / arrow keys via jog dial), P (set/confirm), UP arrow, DOWN arrow. Parameters are addressed numerically. Indexing (subscripts in square brackets) is reached by pressing Fn to toggle the index digit and using the UP/DOWN arrows.

1. Hold P for 3 seconds to enter the parameter entry screen. The display flashes the parameter number.
2. Use UP/DOWN to change each digit; use Fn to move the cursor.
3. Press P to confirm.
4. To enter an indexed value, press P, advance to the index field (right of the parameter number, in square brackets), edit, press P, then edit the value, press P.
5. To enter a hex value, when the value field is highlighted, press Fn until the input mode shows "HEX", then enter the value.
6. A blinking "P" indicates the parameter value has been written to RAM. To copy RAM to ROM (non-volatile), set p0977 = 1 or hold Fn + P until the BOP shows the save progress.

Step-by-Step EPOS Commissioning via BOP20

The sequence below activates the basic positioner on a default SINAMICS S120 with a Drive-CLiQ servo motor. Adjust thresholds for your specific axis limits.

1. Save current state (optional): If the drive was previously configured, perform a factory reset via p0970 = 1 and confirm with P. Drive reboots to factory defaults.
2. Configure drive object: p0108[1] = 11C (hex). The drive queues the new function module configuration.
3. Trigger ramp-up: Cycle 24 V control electronics OFF/ON, or set p0009 = 0 (drive commissioning parameter filter to "ready") then execute p0971 = 1 to start the parameterization mode. After p0971 completes, the drive reboots.
4. Verify function module activation: Read r0108. Bits 2, 3, 4, and 8 should all read 1. If bits are missing, firmware does not include EPOS (license check on certain variants) – contact Siemens with the device serial number.
5. Enable extended setpoint channel: p0150 = 0 (no selection); p1100 = 0 for speed setpoint from EPOS ramp generator.
6. Configure EPOS enable: p2656 = 1 – This is the master enable that powers the basic positioner software module. Without p2656 the positioner parameter set is read-only and no traversing block can be started.
7. Select EPOS operating mode source: p2650 = 0 (setpoint input via parameter / fieldbus) or p2650 = 1 (traversing blocks). For automated indexing applications, leave at 1 and define a block.
8. Set mechanics: Load (LU) per revolution = p2920 (load revolutions); motor revolutions per LU = p2921. For example, a ballscrew with 10 mm pitch and a 5:1 gearbox, with 1 LU = 1 µm: p2920 = 10, p2921 = 50000.
9. Configure position limits: p2570 (positive SW limit), p2571 (negative SW limit). Defaults are ±1e15 LU – restrict to your physical axis envelope.
10. Configure velocity / acceleration: p2572 (max velocity), p2573 (max acceleration), p2574 (max deceleration), p2575 (max jerk). Units are LU/s, LU/s², LU/s³.
11. Configure jog mode: p2585 (JOG velocity 1), p2586 (JOG velocity 2), p2587 (JOG acceleration), p2588 (JOG jerk).
12. Enable OFF3 / OFF2 behavior: p2657 = 1 (activate the positioner; absence causes alarm A07456). Set the controller enable at r0898.0 = 1 by issuing ON via BOP20.
13. Save to ROM: p0977 = 1. The drive copies RAM to ROM, indicated by the BOP showing a clock icon.

Script-Based Commissioning for Repeatable Deployment

Once the parameter set is known, transfer it via script instead of keystroke-by-keystroke entry. Two routes are common in field deployment:

Route A – STARTER / Startdrive Export to Script

Even without STARTER on the commissioning laptop, you can have an offline engineering PC export the parameter list. Open STARTER, configure one drive as a template, choose Target system → Load to PG is not needed; instead use Project → Export → Parameter list to generate a CSV of every parameter and value. The CSV can be reformatted into a USS / PROFIdrive parameter-write script.

Route B – Direct Parameter Write via S7 / HMI / PLC

If a Siemens S7-1500 / S7-1200 controller is on the line, push the parameter set through SINAMICS parameter request telegram (PKE + IND + PWE) using a standard FB (e.g., FB286 "SINA_PARA") in TIA Portal. The FB reads or writes one parameter per call and is suitable for both commissioning and runtime.

Sample ST code fragment for a single parameter write (pseudo-equivalent for the CU310-2 PN/DP and S7-1200/S7-1500):

// Trigger a write of p2656 = 1 (EPOS enable)
#req := TRUE;
#paraNo := 2656;   // p2656
#axisNo := 1;      // drive axis
// Some FBs use the parameter number; others use (DO * 1000 + PN).
// Consult FB286 documentation for exact mapping.

For a complete sequence, call the FB in a loop until all 60+ parameters are written, then trigger p0977 = 1 (Save to ROM) as the final write.

Route C – BOP20 Saved Script File via MMC / SD Card

On CU320-2 with firmware V5.x, parameter sets can be exported to the SD card and reloaded via BOP20. The BOP menu structure under Drive → Up/download (where available on later firmware) provides bulk load. On older firmware, this route is not supported, so plan for Route A or B.

EPOS Enable Signals and Operating Mode Selection

The complete enable chain for a positioning move through EPOS on a default S120 with CU310-2 PN/DP is:

The control word structure for EPOS is found in r2589 (status word EPOS) and the command word is p2586 (control word EPOS). Bits 0, 1, 2, 4, 5, 6, 8, 9, 11, 12, 13 each have documented meanings. Drive the control word from a fast controller (PROFIdrive telegram 111 or telegram 7 with EPOS extension) or from the BOP20 Manual mode for jog.

Verification and Diagnostic Parameters

After enabling EPOS, verify the drive responds correctly without a moving load (motor unloaded or shaft decoupled for first test):

• r2521 – Position actual value (LU, after mechanical conversion).
• r2522 – Velocity actual value (LU/s).
• r2523 – Velocity setpoint (LU/s).
• r2589 – EPOS status word. Bits: 0 = active, 1 = velocity setpoint reached, 2 = position setpoint reached, 4 = following error, 5 = target reached, 6 = home position reached, 8 = jog active.
• r2684 – Following error (LU).
• r2685 – Following error tolerance counter.
• r2719 – Current traversing block number.
• r2740 – Current motion status (Positioning / Homing / Jog).

Set p2542 (positioning window) and p2544 (positioning window time) so that bit 5 of r2589 indicates target reached reliably.

Troubleshooting Matrix

Field-Engineering Notes

• On a default SINAMICS S120 (factory state), the BOP20 commissioning path typically requires only p108 index 1 and p2656 in addition to motor data. The field report confirms this minimal-entry approach produces a working EPOS from defaults.
• Always cycle power after a p0108 change; the function module reconfiguration is not live. A quick alternative on CU310-2 is p0971 = 1 (parameter reset / parameterization level) but this also forces a restart.
• The drive enforces write protection on certain parameters when controller enable is active. Always issue OFF1 (red button on BOP20) before modifying motion limits.
• EPOS bits documented in the List Manual vary by firmware version. The r0108.3 / r0108.4 status indicators confirmed in the source are stable across V4.x and V5.x. Do not assume r0108.5 and above are identical without checking the firmware-specific List Manual.
• For deterministic multi-axis commissioning, build a startup script and reuse it. Each axis saved with p0977 = 1 becomes a stand-alone commissioning target.

FAQ