T400 SPS450 Shear Cut Commissioning Guide for SIMOREG 6RA70 Rotary Drum Shear
A rotary drum flying shear operating with a SIMOREG 6RA70 DC master drive and a T400 technology module is one of the most demanding applications in metals processing. The shear must accelerate, synchronize, and cut on-the-fly without stopping the moving strip. The T400 with the SPS450 software option is the standard Siemens solution for this class of application. This guide walks through the engineering workflow from hardware acceptance through parameter backup, initial parameterization, encoder setup, shear geometry, and acceptance testing.
1. Rotary Drum Shear Application Overview
A flying shear with two counter-rotating drums is mechanically simple but control-wise complex. The drums carry a pair of matched blades that meet at the geometric top or side dead-center of the drum pair. The motor is fed from a SIMOREG 6RA70 DC converter that runs the shear in speed-following or torque-following mode. The T400 technology board is mounted in the free slot of the 6RA70 electronics box and provides the real-time position arithmetic, length measurement, and cut-command generation that the standard drive firmware does not include.
Key process signals in a head-cut / tail-cut installation:
- Proximity switch at the gearbox end: provides the absolute home / zero-pulse reference for the drum. Per the application description, this signal is wired to terminal 83 on the T400, which is the dedicated zero-mark / home-position input.
- Incremental encoder at the non-driving motor end: provides incremental position feedback. This encoder is wired to the CUD (CUD1 or CUD2) of the SIMOREG, not the T400, because the encoder pulses also feed the drive's speed and position controller.
- "Start Cut" command: generated by the upstream line PLC (e.g., S7-300 / S7-400 / TIA Portal controller) and issued when the head or tail of the strip reaches the calculated cut position.
- Cut output: the T400 closes a digital output (e.g., terminal 46 / 47 / 48 depending on the configuration) to trigger the hydraulic or pneumatic shear actuator or to release the blade latch.
The SPS450 software option is firmware that runs on the T400 module and exposes shear-specific function blocks: length measurement, mark detection, acceleration / deceleration ramps, cut angle compensation, and the synchronization logic. It is the recommended path for any new rotary drum shear commissioning because it replaces custom PLC code with a tested library.
2. Hardware Prerequisites
Before applying power, verify the following mechanical and electrical prerequisites. Any item missed here will surface as an unstable cut angle, position drift, or worse, mechanical collision.
- 6RA70 firmware version: confirm the SIMOREG firmware supports the T400 with SPS450. Cross-reference the firmware label on the CUD with the compatibility matrix in the SIMOREG operating instructions.
- T400 module variant: order number 6RA7095-... (verify against the SIMOREG catalog for the specific current rating). The T400 must be ordered with the SPS450 software option enabled, or the option key must be loaded via DriveMonitor or the Parameter Menu Unit (PMU).
- Incremental encoder: HTL or TTL encoder, 1024 / 2048 / 4096 PPR typical. Supply voltage must match the CUD encoder input range (typically 5 V TTL or 24 V HTL via the encoder power terminals on the CUD).
- Proximity switch: PNP, 24 V DC, normally open. Mounting position must be verified with the drum at the defined home (blade tip aligned with the strip passline).
- Shielded cable: encoder and home-pulse cabling must be shielded, with the shield bonded to the cabinet ground bar at one end (or both ends through a low-impedance bond) per the Siemens EMC installation guidelines.
- DriveMonitor or PMU access: a PC with DriveMonitor installed (RS232 to the X500 PMU port or via the optional USS / PROFIBUS / PROFINET adapter) for parameter upload/download and online trace.
- Strip simulator / line simulator: a hand-pulse generator or the upstream PLC in simulation mode, so the T400 can be exercised without a moving strip for the first cut cycle.
3. Wiring Configuration: T400, CUD, and Field Devices
The T400 module has its own terminal strip. Terminals 80 to 89 are reserved for digital inputs on the T400. Terminal 83 in this application is configured as the zero-pulse / home reference for the SPS450 shear function. The proximity switch PNP output is wired:
- Brown / red (+24 V) to a fused 24 VDC source derived from the cabinet power supply.
- Blue (0 V) to the 24 V common.
- Black (output) to T400 terminal 83.
The T400 digital input common for terminals 80 to 87 is typically terminal 84 (0 V reference) and terminal 85 (+24 VDC reference), or a similar pair, depending on the hardware revision. Verify against the T400 terminal assignment sheet shipped with the unit.
The incremental encoder at the non-driving motor end is wired to the CUD encoder input (terminal X105 on the SIMOREG 6RA70 CUD1, or the equivalent on CUD2). Wiring follows the standard SIMOREG convention:
- Encoder channel A and channel A# (or /A).
- Encoder channel B and channel B# (or /B).
- Encoder channel R (zero pulse) and channel R# if used.
- Encoder power (typically +5 V or +24 V, depending on the encoder).
- Shield terminated to the CUD ground stud.
If the encoder has 5 V TTL outputs, the SIMOREG's onboard encoder interface is used directly. If the encoder is 24 V HTL, verify that the CUD variant matches; some early CUD1 boards required an external level converter.
4. T400 SPS450 Software Architecture
The SPS450 firmware package is structured as a set of function blocks that run on the T400's processor. The blocks cover:
- Length counter: integrates the strip speed signal to compute the length of strip that has passed a reference point (e.g., the entry-side measuring roll).
- Position controller: compares the actual drum angle to a calculated demand angle and outputs a speed correction to the SIMOREG's main speed setpoint.
- Cut-window generator: opens a cut window when the drum angle is within an acceptable range of the ideal cut angle, and issues the cut trigger inside that window.
- Acceleration / deceleration profiles: ramps the shear up to line speed and back down to creep speed for the next cut.
- Handshake with the line PLC: Start Cut input, Cut Done output, fault bits, and ready / not-ready handshake.
Configuration is done through indexed parameters. In the SIMOREG 6RA70 the T400 technology parameters appear in a parameter block designated "U" (for user technology). For example, U001 to U010 control the shear geometry, U020 to U030 control the position-controller gains, and U040 to U060 control the I/O mapping. The exact range is version-dependent and must be confirmed against the T400 manual for the SPS450 release installed.
5. Parameter Backup Procedure
Two backups are required: one of the as-shipped drive and one of the commissioned drive. The committed parameter file is the legal record of what was tuned, and is what the OEM customer will need for future maintenance or for cloning the project to sister machines.
- Connect to the drive: with DriveMonitor, connect to the SIMOREG via serial (X500 PMU) or via the optional PROFIBUS / PROFINET adapter. The drive must be in commissioning mode (operation disabled, terminal 37/38 open if wired as enable input).
- Upload all parameters: select Drive → Upload All Parameters. This transfers the complete parameter set from the drive RAM to DriveMonitor. The upload includes the standard SIMOREG parameters (P-range), the BICO interconnects, the T400 technology parameters (U-range), and the SPS450 shear-application parameters.
-
Save as commissioning baseline: file → Save As, with a name that includes the project number, machine serial, and date. Example:
DRUM_SHEAR_001_SN_12345_BASELINE_2024.dmp. - Export to PDF: for the paperless documentation record, use DriveMonitor's print-to-PDF function on the parameter list view, or export the parameter list to CSV and print from Excel. Most plants require the PDF in the machine's CE technical file.
- Save to a non-volatile medium: copy the .dmp file and the PDF to a USB stick that is stored in the cabinet document holder.
- Save to the SPS / engineering repository: upload the .dmp to the engineering server and tag it with the project ID. The end customer will need this file at FAT, SAT, and warranty review.
6. Commissioning Sequence
The following sequence is the standard commissioning order for a T400 SPS450 shear on a 6RA70. It assumes the mechanical installation, encoder mounting, and proximity-switch mounting are complete and aligned. Do not skip steps. Each step has a defined acceptance gate before the next is started.
6.1 Power-up and ID of the 6RA70
- Apply 400 VAC (or the configured line voltage) to the SIMOREG. Verify the green Power LED on the CUD is on and the PMU displays
oP. xxx(operate / standby). - Set access level to commissioning via P051 = 3 (typical value; verify against the firmware version's manual).
- Enter the nameplate data for the DC motor: armature current (P083), armature voltage (P084), field current (P082), field voltage, speed, encoder PPR, and thermal class.
- Run the drive's automatic motor identification (armature and field current controller autotune, typically initiated via a parameter such as P051 = 5 / 6 or via the drive's optimized pulse-pattern routine, depending on firmware release). The motor shaft may rotate briefly. Confirm the area is clear and the motor is uncoupled from the drum if the procedure requires.
6.2 Encoder Setup on the CUD
- Configure the CUD encoder input: PPR, signal level, direction sense, and whether channel R is used.
- Rotate the drum by hand and verify the speed actual value in DriveMonitor follows the rotation. Sign convention: drum rotation that advances the strip downstream must produce a positive speed actual.
- Set the speed-controller filter, the speed-controller pre-control, and the current-controller pre-control to safe initial values (low gain, no integral action, or low integral time) before first run.
6.3 Home Position: Terminal 83 Proximity Switch
- Manually rotate the drum until the blade tips are geometrically aligned with the strip passline at the cut point. This is the mechanical home.
- Adjust the proximity switch bracket so the target aligns with the switch at this position. The proximity switch should be clean, free of metal debris, and not subject to vibration-induced false triggering.
- In the T400 configuration (SPS450), set the home-search mode to one-time reference at power-up or re-reference on Start Cut, depending on whether the drum is parked at home between cuts or parked at an offset.
- Trigger a home search via the SPS450 commissioning routine and confirm that terminal 83 fires exactly once per drum revolution at the mechanical home position. The status word in DriveMonitor should show the home flag toggling in sync with the proximity switch.
6.4 Shear Geometry and Cut Length
- Enter the drum diameter (effective, accounting for blade thickness and wrap), the number of blades per drum, and the gear ratio between motor and drum.
- Enter the cut length: the distance the strip travels between two cuts. This is the parameter that defines head cut, tail cut, and slab cut lengths in succession.
- Define the cut-window width (in degrees of drum rotation). A narrow window improves cut-angle precision but requires tighter speed-following. A wide window is more forgiving but degrades cut quality. Start with the SPS450 default and tighten after first successful cut.
- Enter the upstream-line speed input scaling. The length counter and position controller depend on a clean line-speed signal from the upstream measuring roll or the line PLC.
6.5 Speed Controller Tuning
- Run the shear unloaded (no strip) in speed-following mode at 10% of rated speed. Use DriveMonitor's trace function to capture speed setpoint, speed actual, and current.
- Tune the speed controller: increase proportional gain until the response shows minimal overshoot, then add integral action. A starting point of Pn = 5 to 10 and Tn = 0.5 s to 1.0 s is typical for a DC drive of this class, but the final value must be set on site.
- Step the line speed from 10% to 100% and back. The shear must track without oscillation, with a position error that stays within the cut window.
6.6 Flying Shear Synchronization and First Cut
- Enable the SPS450 shear function. The T400 takes ownership of the position controller and starts commanding the SIMOREG speed to keep the drum angle locked to the moving strip.
- Issue a Start Cut command from the line PLC. The T400 computes the time to the next cut window and triggers the cut output at the ideal angle.
- Inspect the cut: blade marks must be square to the strip edges, the cut angle must be within the customer's tolerance (typically +/- 0.5 to 1.0 degrees), and there must be no burr or tag on the cut edge.
- If the cut angle is consistently biased, adjust the home-position offset (the small angular correction between the proximity-switch trigger point and the true blade-on-strip position).
7. Verification and Acceptance Tests
Acceptance is documented with a parameter sheet and a test report. The standard acceptance matrix for a rotary drum shear is:
| Test | Method | Acceptance Criterion |
|---|---|---|
| Home repeatability | 10 successive home searches with the drum at rest | Spread < 0.1 degrees of drum rotation |
| Speed-following error | DriveMonitor trace at 100% line speed, steady state | Position error < 50% of cut-window width |
| Cut angle accuracy | Measure the angle of the cut edge against a reference square | Within +/- 1.0 degree (typical contract spec) |
| Cut-length accuracy | Measure 10 consecutive cut pieces with a calibrated tape | Within +/- 2 mm on a 6 m cut (typical) |
| Acceleration / deceleration | Trace the current limit during a cut cycle | Current does not exceed drive rating for more than 3 s |
| Fault response | Force a strip-loss signal and an encoder-loss signal | T400 disables the cut output within 50 ms |
| Parameter backup | Upload commissioned parameters to DriveMonitor and save to PDF | PDF stored in CE technical file and engineering server |
8. Troubleshooting Matrix
| Symptom | Likely Root Cause | Action |
|---|---|---|
| Cut angle drifts over time | Encoder slip on the shaft, or proximity switch vibration | Check encoder coupling, re-tighten bracket, add anti-vibration mount |
| Drum oscillates during line speed change | Speed controller gain too high, or position loop gain too high | Reduce Pn on speed controller, then reduce SPS450 position gain |
| No cut output, drum tracks but does not fire | Cut window not opened, or Start Cut input wiring reversed | Verify the Start Cut polarity in the SPS450 handshake config, and verify cut-window enable flag |
| Cut window fires twice per revolution | Proximity switch triggering on a second feature (e.g., drum bolt head) | Check the target geometry, reduce switch sensing range, or relocate switch |
| Home position is offset after power cycle | Drum parked at an offset, not at home, and home search is one-shot only | Set SPS450 to re-reference on every Start Cut, or change parking routine |
| F0004 / F0005 / drive fault at start | Enable wiring missing, or motor overcurrent during first run | Verify terminal 37/38 (or the configured enable), reduce acceleration ramp, check motor nameplate data |
| Shear runs only at creep speed | Line speed signal missing or scaled incorrectly | Verify the line-speed input from the upstream PLC or measuring roll, check scaling in SPS450 |
| Position controller saturates | Drum inertia too high for the configured acceleration, or mechanical bind | Check drum bearings, increase acceleration ramp time, verify motor / gearbox rating |
9. Field-Commissioning Notes
A few caveats that come up repeatedly on real sites. They are not in the standard manual and are worth recording in the commissioning log.
- Home-search direction: the SPS450 home-search routine searches in a defined direction. If the drum is parked on the wrong side of the home, the first search can take one full revolution. This is normal but can alarm the operator. Document the park position in the operating instructions.
- Encoder PPR and SPS450 cut angle: the cut-angle resolution is limited by the encoder PPR. With 1024 PPR and a one-blade drum, the angular resolution is roughly 0.35 degrees. If the cut-angle specification is tighter than that, upgrade to 2048 or 4096 PPR.
- Drum wear and home drift: as the blades wear, the effective drum diameter shrinks, and the home reference drifts. Plan a periodic re-calibration interval (typically every 50 000 cuts) and document the procedure.
- Spare-parts T400: a spare T400 with the SPS450 option key loaded should be kept on site. Replacing a T400 without the option key loaded results in a non-functional shear and a long commissioning visit.
- EMC and cable routing: keep the encoder cable in a separate tray from the power cables. The Siemens EMC installation guide (and the SIMOREG installation notes) specify a minimum separation; violations will show up as erratic position counts under line disturbance.
10. Documentation Handover
At the end of commissioning, the engineer hands over the following documents. They are part of the SAT (site acceptance test) dossier and are required for the CE technical file:
- Commissioned parameter file in DriveMonitor format (.dmp), committed to the engineering server.
- PDF export of the parameter list, including the T400 SPS450 U-range and the BICO interconnects.
- DriveMonitor trace recordings of: speed step response, position-controller behavior at line speed, current limit during a cut cycle, fault response.
- Updated electrical drawing set: drive schematic, encoder wiring, proximity-switch wiring, E-stop chain.
- Commissioning log book: every parameter change, with date, time, engineer name, and the reason for the change.
- Operator instructions: park position, Start Cut procedure, fault reset, and emergency stop behavior.
For sister-machine cloning, the .dmp file is the starting point. Drive-specific items (motor nameplate, encoder PPR, line-speed scaling) must be re-verified per machine. The T400 SPS450 function block settings can usually be carried over unchanged once the geometry and cut-length parameters are confirmed.
What is the SPS450 software option on the T400?
SPS450 is a Siemens firmware / software package that runs on the T400 technology module and provides ready-made function blocks for shear, cut-off, and length-measurement applications. It is the recommended software path for new rotary drum shear commissions because it replaces custom PLC code with a tested library. The option key is loaded on the T400 module and is required for the shear blocks to be available.
Why is the home-position proximity switch wired to terminal 83 on the T400, not the CUD?
Terminal 83 on the T400 is the dedicated zero-mark / home-position input that the SPS450 home-search routine references. The CUD encoder input is for the incremental position signal only. Separating the home reference from the incremental encoder allows the SPS450 to re-reference after a power cycle or after a fault without disturbing the encoder wiring, and it lets the home search run independently of the drive's speed controller.
How do I save the T400 SPS450 parameters to a PDF for documentation?
Connect DriveMonitor to the SIMOREG via the X500 PMU serial port (or via the optional PROFIBUS / PROFINET adapter), select Drive → Upload All Parameters to read the live parameter set into the PC, save the .dmp file with a project-specific filename, then print the parameter list view to PDF. Keep both the .dmp file and the PDF in the machine's CE technical file and on the engineering server for sister-machine cloning and warranty review.
Can I clone a commissioned T400 to a sister machine?
Yes, but verify the .dmp file after download. The standard SIMOREG parameters, BICO interconnects, and the T400 U-range parameters all transfer, but machine-specific items such as the motor nameplate, encoder PPR, and line-speed scaling must be re-entered and re-verified per machine. Always run a parameter comparison report before the first energization on the sister machine.
What is the typical cut-angle tolerance for a rotary drum shear?
Most contract specifications call for +/- 0.5 to +/- 1.0 degrees of cut-angle error on a flying shear. The achievable tolerance is limited by the encoder PPR, the speed-controller bandwidth, and the line-speed stability. With a 1024 PPR encoder, the angular resolution is about 0.35 degrees; for tighter tolerances, upgrade to 2048 or 4096 PPR and tighten the SPS450 cut window accordingly.