Overview of S110 EPOS Jog Mode and the Ramp Limitation
The SINAMICS S110 drive running the Basic Positioner (EPOS) operating mode with standard telegram 111 exposes three production motion modes: jog, traversing blocks, and MDI (Manual Data Input). In jog mode the drive responds to a binary jog-1 / jog-2 select bit and accelerates to the velocity defined in P2585 (EPOS jog 1 setpoint velocity) or P2586 (EPOS jog 2 setpoint velocity), scaled by the velocity override in P2646. The motion continues for as long as the jog command bit is held active and stops (with the drive's natural deceleration) when the bit is removed. No programmed target position is required, which makes jog mode the natural fit for turning axes, manual hand-wheel operations, and continuous-feed machine functions.
The behavioural limitation that surfaces in most real commissioning work is that the jog accel/decel ramp is not directly parameterised. The jog mode reads its target velocity from P2585 / P2586 and reads its ramp shape from the LR ramp-function generator of the position controller (P2481 ramp-up time, P2481[1] ramp-down time, P2482 rounding times). A change to P2481 to make the jog snappier simultaneously makes every fine positioning move in the traversing-blocks mode overshoot or oscillate. There is no P25xx parameter pair on the S110 that scales the jog ramp independently of the underlying LR ramp, in the same way that P2617 and P2618 scale the ramp of the MDI mode. The official Siemens-recommended workaround is to execute the same speed-controlled motion through MDI Setup Mode (P2653 = 1), which exposes P2617 (MDI acceleration override) and P2618 (MDI deceleration override) as the missing jog-ramp scalers.
Why No Dedicated Jog Ramp Override Exists on S110
EPOS jog mode on the S110 inherits its accel/decel behaviour from the position controller's ramp-function generator rather than from a dedicated jog ramp. This is documented in the SINAMICS S110 Function Manual and confirmed by Siemens support: P2585 and P2586 define the target velocity for the two jog inputs, and P2646 scales both of them globally, but no parameter pair exists to scale the jog ramp alone. The same behaviour is present on the SINAMICS S120 but the S120's broader parameter set gives the integrator more wiggle room with overriding profile limits higher in the control hierarchy.
Concretely, the S110 EPOS parameter range relevant to a jog motion includes:
-
P2585– EPOS jog 1 setpoint velocity (signed, 1000 LU/min) -
P2586– EPOS jog 2 setpoint velocity (signed, 1000 LU/min) -
P2587– EPOS jog 1 traversing distance (incremental jog, 1000 LU) -
P2588– EPOS jog 2 traversing distance (incremental jog, 1000 LU) -
P2646– EPOS velocity override (0 – 400 %, applies to both jog inputs)
None of these parameters scales the acceleration or deceleration slope. The integrator who tries to back-derive a ramp from the existing parameter set is left with a binary choice: change P2481 globally (and trade fine-positioning behaviour for jog response), or accept the slow jog. The MDI Setup Mode is the only on-board remedy that breaks this trade-off cleanly.
Workaround: Drive Jog Motion Through MDI Setup Mode
MDI Setup Mode is a sub-mode of the MDI block in EPOS. The base MDI block is designed for positioning: a target position is loaded into P2640 (MDI fixed setpoint position), a velocity into P2641 (MDI fixed setpoint velocity), and the drive ramps to the position and stops. The sub-mode "Setup" (also referred to in Siemens documentation as "Setting-up selected") is selected by setting P2653 = 1 and disables the target-position requirement. The drive then behaves as a speed-controlled jog with the following three additional parameter inputs becoming active:
-
P2617– MDI acceleration override, in % of the underlying LR ramp time -
P2618– MDI deceleration override, in % of the underlying LR ramp time -
P2651– MDI direction (positive, negative, or hardware-controlled)
With P2653 = 1 in place, a rising edge on the MDI setpoint-acknowledge bit (P2652) starts the motion in the programmed direction at the velocity held in P2641, scaled by P2646. The motion continues until the direction bit is removed, at which point the drive brakes with the deceleration defined by the effective P2481[1] ramp-down time scaled by P2618. This is the only path on the S110 to independent accel/decel scaling for a speed-controlled motion, and it is the documented Siemens workaround for the missing jog ramp parameter.
Parameter Map: S110 EPOS Jog vs MDI Setup Mode
| Parameter | Description | Unit / Range | Jog mode | MDI Setup mode (P2653=1) |
|---|---|---|---|---|
| P2585 | Jog 1 setpoint velocity | 1000 LU/min | Yes (target velocity, jog-1 select) | Not used |
| P2586 | Jog 2 setpoint velocity | 1000 LU/min | Yes (target velocity, jog-2 select) | Not used |
| P2640 | MDI fixed setpoint position | 1000 LU | Not used | Ignored in Setup mode |
| P2641 | MDI fixed setpoint velocity | 1000 LU/min | Not used | Target velocity |
| P2646 | EPOS velocity override | 0 – 400 % | Scales P2585 / P2586 | Scales P2641 |
| P2617 | MDI acceleration override | 0.1 – 100 % | Not available | Scales P2481[0] for MDI motion |
| P2618 | MDI deceleration override | 0.1 – 100 % | Not available | Scales P2481[1] for MDI motion |
| P2650 | MDI positioning mode | 0 = absolute, 1 = relative | Not used | Not used in Setup mode |
| P2651 | MDI direction | 0 = pos, 1 = neg, 2/3 = ext | Not used | Direction of motion |
| P2652 | MDI acknowledgment | Edge 0→1 | Not used | Starts motion |
| P2653 | MDI Setup mode | 0 / 1 | 0 | 1 |
| P2481[0] | LR ramp-function generator ramp-up time | 0.0 – 600.0 s | Basis (no override) | Basis for P2617 scaling |
| P2481[1] | LR ramp-function generator ramp-down time | 0.0 – 600.0 s | Basis (no override) | Basis for P2618 scaling |
| P2482[0] | LR ramp-function generator initial rounding | 0.0 – 10.0 s | Applies (S-curve smoothing) | Applies (S-curve smoothing) |
| P2482[1] | LR ramp-function generator final rounding | 0.0 – 10.0 s | Applies (S-curve smoothing) | Applies (S-curve smoothing) |
The decisive columns are the last two: in jog mode there is no per-mode override for the underlying LR ramp; in MDI Setup mode P2617 / P2618 are active and act as the missing jog-ramp scalers. The base ramp time stored in P2481 is unaffected – only the effective MDI ramp time is scaled.
Step-by-Step Commissioning Procedure
- Confirm telegram and basic configuration. Verify the drive is configured for basic positioner (EPOS) and the PROFIdrive telegram is set to telegram 111 (P0922 = 111). Confirm that the axis has been referenced (set-point / actual position match, EPOS "referenced" status bit set), or that referencing is intentionally disabled for endless rotary motion.
-
Set the LR base ramp time. Configure
P2481[0](ramp-up) andP2481[1](ramp-down) to the values that match the slowest acceptable fine-positioning motion in the machine. These are the base ramp times. P2482[0] and P2482[1] provide the S-curve smoothing. Typical starting points: P2481[0] = P2481[1] = 0.1 s, P2482[0] = P2482[1] = 0.02 s. -
Configure MDI mode parameters. Set
P2641to the desired jog velocity (1000 LU/min, signed),P2646= 100 % (default),P2653= 1 (Setup mode enabled), andP2650= 0 or 1 (does not matter in Setup mode, but must be valid). -
Set the MDI ramp overrides. Set
P2617andP2618to the desired percentages. The effective ramp time for MDI Setup motion isT_eff = P2481[0] × (P2617 / 100 %)for acceleration, andT_eff = P2481[1] × (P2618 / 100 %)for deceleration. A value of 50 % halves the ramp time and doubles the effective acceleration. A value of 25 % quarters it. - Wire the MDI control bits in the PLC. On standard telegram 111, the MDI control is routed through PosStw (position control word) and STW2. The bit pattern for "start MDI motion in direction of P2651 with edge on P2652" must be held active. The direction bit in P2651 (or the external direction control bit in STW2) must be held active for the entire motion.
- Verify the trace. Use the S110 Starter / Startdrive trace tool to record the velocity setpoint, actual velocity, and the torque / current during a MDI Setup motion. The accel/decel slope must show a clear, linear (or S-curve if P2482 is non-zero) profile that lands on the target velocity from P2641 scaled by P2646 within the time predicted by the formula above.
- Tune the override values. Iterate P2617 and P2618 to match the desired jog response. Typical values for a manual-jog application on a small servo: P2617 = 30 % to 60 % to give a 0.03 s to 0.06 s acceleration on a 0.1 s base ramp. Heavier axes with higher inertia use higher percentages (longer ramp) or rely more on the S-curve rounding in P2482.
- Disable the original jog motion. Remove the jog select bits from the PLC or set P2585 = P2586 = 0 if the application no longer requires the standard jog mode. This eliminates the slow ramp as a confusing second option for the operator.
Telegram 111 Control and Status Word Integration
Telegram 111 is the standard PROFIdrive telegram for EPOS. It defines 4 words in each direction. The control side (PLC → drive) consists of:
| Word | Bit | Function in MDI Setup mode |
|---|---|---|
| STW1 | 0 – 15 | Standard drive state machine (ON / OFF, enable, fault ack, jog bits, etc.) |
| STW2 | 0 – 15 | Direction, MDI mode select, setup-mode select, signal sources |
| PosStw | 0 – 15 | MDI positioning mode (absolute / relative), MDI acknowledgment edge, MDI setup-mode |
| Override | 0 – 15 | Direct write to P2646 (velocity override) |
The status side (drive → PLC) mirrors with ZSW1, ZSW2, PosZsw, and the actual values. The PLC's job is to:
- Set
Override(telegram word 4) to the velocity override percentage (0 – 400 %, where 16384 = 100 % in normalised form). - Hold the MDI mode select bit (STW2) and the Setup-mode select bit (PosStw) active.
- Set the direction bit (STW2 bit 11/12 for positive / negative direction) for the duration of the motion.
- Generate a rising edge on the MDI acknowledgment bit (PosStw bit 5) to start each motion. The drive echoes acknowledgment in ZSW2 / PosZsw.
Ramp Profile Mathematics and Acceleration Sizing
The motion profile produced by EPOS is a classical trapezoidal or S-curve profile, parameterised by the LR ramp-function generator. The mathematics are summarised below for sizing the MDI override values against the target velocity.
Linear (trapezoidal) accel profile:
a_eff = v_target / T_eff
where:
-
v_target= P2641 × (P2646 / 100 %) in 1000 LU/min -
T_eff= P2481[0] × (P2617 / 100 %) in seconds (acceleration), or P2481[1] × (P2618 / 100 %) for deceleration
Unit conversion: the EPOS speed is normally expressed in 1000 LU/min, but acceleration is normally expressed in 1000 LU/s². To compute the peak acceleration in the same units, first convert the velocity to 1000 LU/s by dividing by 60:
v_target_s = (P2641 × P2646/100) / 60 in 1000 LU/s
a_eff = v_target_s / T_eff in 1000 LU/s²
Worked example: P2641 = 30 000 (1000 LU/min = 30 LU/s) = 0.5 LU/s if 1 LU = 1 motor rev. P2646 = 100 %. P2481[0] = 0.1 s. P2617 = 50 %.
Effective ramp time: T_eff = 0.1 × 0.5 = 0.05 s.
Effective acceleration: a_eff = (30 000 / 60) / 0.05 = 500 / 0.05 = 10 000 [1000 LU/min / s] = 10 000 / 60 = 166.67 [1000 LU/s²].
S-curve profile: when P2482[0] (initial rounding) and P2482[1] (final rounding) are non-zero, the drive replaces the linear ramp corners with sinusoidal jerk-limited transitions. The average accel/decel value remains the same as the linear case, but the peak jerk is bounded. For a continuous-feed application where smoothness is critical (e.g. glass handling, textile feeding), P2482 = 30 % to 50 % of P2481 is a good starting point. For a punch-press jog where sharp response is critical, leave P2482 at zero and use the linear profile.
For the general theory of motion profiles and the trade-off between jerk-limited and trapezoidal profiles, see the Texas Instruments application note on acceleration and deceleration profiles for bipolar stepper motors, which provides a clean mathematical treatment of the same problem class:
Comparison: Jog, MDI Setup, MDI Positioning
| Feature | Jog mode | MDI Setup mode (P2653=1) | MDI Positioning mode (P2653=0) |
|---|---|---|---|
| Target position required | No | No | Yes (P2640) |
| Velocity source | P2585 / P2586 + P2646 | P2641 + P2646 | P2641 + P2646 |
| Independent accel ramp | No (shared P2481[0]) | Yes (P2617 override) | Yes (P2617 override) |
| Independent decel ramp | No (shared P2481[1]) | Yes (P2618 override) | Yes (P2618 override) |
| Stop on removal of input | Yes (uses P2481[1]) | Yes (uses P2618-scaled P2481[1]) | No – drive runs to P2640 |
| PLC code complexity | Lowest (1 binary input per direction) | Medium (mode + direction + edge) | Medium (mode + direction + edge + position) |
| Recommended use | Slow fine jog, OEM hand-wheels | Continuous-feed, machine jog, high-speed jogging | Indexed move triggered by PLC |
The comparison confirms the engineering choice: if independent accel/decel scaling is required for a speed-controlled motion, MDI Setup mode is the only on-board solution on the S110.
Verification, Diagnostics, and Trace Recording
After the parameterisation above, perform the following verification sequence on the bench or in the machine:
- Static check. With the drive enabled but no MDI motion triggered, read back P2641, P2617, P2618, P2646, P2653 in the parameter view of Starter / Startdrive. Confirm that P2653 = 1 and P2646 = 100 % (or the desired scaling). The override value written by the PLC must be visible in P2646 within one telegram cycle.
- Open-loop check. Trigger a short MDI motion (5 mm or so) in the MDI Setup mode and watch the velocity setpoint and actual velocity on the trace. The acceleration slope must be linear (or S-curve if P2482 is non-zero) and the deceleration must match the symmetry expected from P2617 and P2618. If the trace shows the slow jog-style ramp, the PLC has not actually entered Setup mode; check PosStw bit mapping.
- Direction reversal check. Trigger motion in positive direction, stop, then negative. Confirm the deceleration on stop matches P2618 and that the subsequent acceleration in the new direction matches P2617. A 0% override on P2618 will produce near-instantaneous braking (limited by the drive's internal current limit) – useful for fast-stop applications.
- Override sweep. Run the same motion with P2646 at 25 %, 50 %, 75 %, and 100 % to confirm the velocity override is correctly multiplying P2641. The trace will show four different plateau velocities at the same ramp times, confirming the override is decoupled from the accel ramp.
- Ramp sweep. Run the same motion with P2617 at 25 %, 50 %, 75 %, and 100 % to confirm the override is correctly scaling the LR ramp time. The plateau velocity is constant across the four runs but the time-to-plateau is proportional to the override value.
- Fault injection. Disconnect the PROFIdrive telegram during a MDI motion. The drive must fault with F08501 (PROFIdrive telegram failure) within the configured watchdog time (P2043). Reconnect and acknowledge the fault with the standard STW1 bit 7. This validates the watchdog and telegram-monitoring configuration.
Troubleshooting Matrix
| Symptom | Likely root cause | Resolution |
|---|---|---|
| Jog motion still slow after configuring P2617 / P2618 | PLC is still in standard jog mode, not MDI Setup mode | Verify PosStw bit pattern in the PLC and P2653 = 1; check ZSW2 / PosZsw echo for "Setup mode active" |
| MDI motion does not start | Missing or wrong-polarity edge on P2652 (PosStw bit 5) | Generate a 0→1 transition on the acknowledge bit; verify with a watch table in TIA Portal |
| Motion runs in wrong direction | P2651 polarity or STW2 direction bit mismatch | Verify P2651 = 0 for positive, 1 for negative; verify STW2 bit 11/12 polarity matches the wiring |
| Velocity is double or half the expected | P2646 not at 100 %, or telegram override word not normalised correctly (16384 = 100 %) | Normalise the override word: Override_word = (P2646 / 100 %) × 16384 |
| Drive faults F07411 / F07412 on aggressive ramps | Drive current limit reached at low P2617 / P2618 | Increase P2617 / P2618, or increase P2481[0] / P2481[1] (base ramp), or raise current limit if mechanical design allows |
| Drive faults F08501 (telegram failure) | Watchdog time P2043 too short for telegram cycle | Increase P2043 to 3× the bus cycle time |
| Position drift on stopping in MDI Setup | P2571 (positioning window) too tight for the residual velocity at stop | Increase P2571, or tighten P2618 to ensure clean stop within the window |
| Overshoot on direction reversal | P2617 too aggressive (insufficient ramp time) | Increase P2617 (longer ramp) or add P2482[0] (initial rounding) for S-curve smoothing |
| Motor stalls at high override | Torque limit reached; current limit P0640 too low for the required accel | Check P0341 / P0342 (motor data), P1520 / P1521 (torque limits), and P0640 (current limit) |
| Fault F07414 (motor model / encoder fault) on rapid accel | Encoder resolution insufficient for the demanded accel | Reduce P2617, or check encoder wiring and P0400 (encoder type) |
Field-Commissioning Notes and Edge Cases
Endless rotary motion (turning axes). For a turning axis that never references and never expects a position, the MDI Setup mode is the natural fit. The PLC drives STW2 direction bit directly and toggles the PosStw acknowledge bit to start the motion. Position overrun is not a concern because the axis is treated as endless modulo in P2921 / P2922.
Referenced linear axes. For a referenced linear axis, the PLC must still monitor the software limit switches (configured via P2574 / P2575 in some firmware versions, or via the user-software SLS in the PLC) during the MDI Setup motion, because the MDI Setup mode is intentionally position-agnostic. A missing limit check can drive the axis into the hardware end stop.
PLC-to-drive timing. The PROFINET telegram cycle time must be consistent with the ramp time. For a 50 ms effective ramp, a 4 ms telegram cycle is fine (12 samples per ramp). For a 5 ms effective ramp, drop the telegram cycle to 1 ms or accept that the trace will under-sample the ramp shape.
Override combined with MDI override. P2646 (velocity override) and P2617 / P2618 (accel/decel override) are independent. P2646 scales the velocity target; P2617 / P2618 scale the ramp time. The effective acceleration is therefore a function of both:
a_eff = (P2641 × P2646 / 100 %) / (P2481[0] × P2617 / 100 %)
When the operator changes P2646, the effective acceleration changes proportionally. To keep the effective acceleration constant across override changes, scale P2617 and P2618 by 1 / (P2646 / 100 %) in the PLC. This is a common requirement in master-slave or tension-control applications.
Safety integration. MDI Setup mode bypasses the standard jog torque-limit / quick-stop logic in some firmware versions. Always test the safe-torque-off (STO) input (X130.5 / X130.6 on S110) and the safe-stop-1 (SS1) function before taking the machine into production. The STO input must cut motion within the SS1 time budget (typically 250 ms to 2 s) regardless of the MDI motion state.
Firmware version note. The exact parameter numbers and bit mapping for P2653, P2651, P2652 are firmware-version-sensitive. Always cross-check against the SINAMICS S110 Function Manual that matches the firmware version on the drive (visible in r0018). Newer firmware versions (FW 4.4 and later) may expose additional jogging / setup-mode features, including dedicated jog ramp overrides on selected variants – verify against the official List Manual before assuming the limitation exists on the firmware in question.
Commissioning checklist.
- FW version checked against the SINAMICS S110 List Manual (r0018)
- Telegram 111 active in P0922 = 111
- Axis referenced (or endless mode confirmed) before MDI motion
- P2481[0], P2481[1] set to base ramp times that satisfy fine positioning
- P2617, P2618 set to override percentages for the desired jog response
- P2641, P2646, P2653 set to the MDI Setup configuration
- PLC code drives the correct PosStw bits for MDI mode + direction + acknowledge edge
- Trace recording confirms the predicted ramp shape
- STO / SS1 function tested with MDI motion active
Frequently Asked Questions
Why does the SINAMICS S110 EPOS jog mode have no accel/decel override parameter?
The S110 EPOS jog mode inherits its ramp from the position controller's LR ramp-function generator (P2481[0] / P2481[1]). The standard MDI mode exposes P2617 / P2618 as ramp overrides, but the jog mode in the S110 firmware does not expose a similar pair. The only on-board workaround is to execute the speed-controlled motion through MDI Setup mode (P2653 = 1), which makes P2617 / P2618 active for that motion.
What is the difference between MDI Positioning mode and MDI Setup mode?
MDI Positioning mode (P2653 = 0) requires a target position in P2640 and decelerates to a stop on that position. MDI Setup mode (P2653 = 1) ignores the target position, accelerates to the velocity in P2641, and runs at that velocity for as long as the direction control bit is held. MDI Setup mode is the equivalent of a jog with the missing accel/decel override exposed through P2617 and P2618.
How is the effective ramp time calculated for MDI Setup mode?
The effective ramp time is the underlying LR ramp time scaled by the MDI override: T_eff_accel = P2481[0] × (P2617 / 100 %), T_eff_decel = P2481[1] × (P2618 / 100 %). For example, with P2481[0] = 0.1 s and P2617 = 50 %, the MDI Setup motion accelerates over 0.05 s.
Can I use the MDI Setup mode for a continuously rotating axis that is never referenced?
Yes. MDI Setup mode is the natural fit for an endless rotary axis. The PLC drives the direction bit (P2651 or STW2 bit 11/12) and toggles the acknowledge bit (P2652) to start the motion. The drive ignores the position and software limit switches unless the PLC enforces them. Use the safety functions (STO, SS1, SLS in the safety module) to enforce the limit switches externally.
What happens to the position when the MDI Setup motion stops?
The drive brakes with the deceleration defined by P2481[1] × (P2618 / 100 %) and holds the final position. The position controller will report the actual position in r2521 / r2522 (or the telegram's actual-position word). For a referenced axis, the position is consistent with the previous referencing state. For an endless axis, the position keeps a continuous count modulo the configured modulo range.
Does the velocity override (P2646) affect the MDI acceleration ramp time?
No. P2646 scales the target velocity; P2617 / P2618 scale the ramp time. They are independent. The effective acceleration is proportional to P2646, so a change in P2646 will change the effective acceleration for the same P2617 value. To keep the effective acceleration constant across override changes, scale P2617 inversely with P2646 in the PLC.
Which SINAMICS manuals document the MDI Setup mode parameters?
The S110 Function Manual "Basic Positioner (EPOS)" and the SINAMICS S120 / S150 List Manual cover the MDI mode parameters in detail. The List Manual is the authoritative source for parameter ranges, default values, and bit-level field definitions. The Firmware version visible in r0018 must be cross-checked against the List Manual edition for the drive in question.