Overview: Why There Is No Practical 611A Simulator
The question comes up on every retrofit desk: "Is there a software simulator for a SIMODRIVE 611A driving two motors?" For the analog family (611A), the answer in practice is no useful one. The 611A is a hardware-parameterized analog drive: setpoints arrive as +/-10 V, enables arrive as 24 V hardware signals, and axis behaviour is set by DIP switches, potentiometers and plug-in personality/option modules rather than by a downloadable project file. There is no digital bus configuration to emulate and no parameter database to load, so a PC model would reproduce almost nothing that actually causes commissioning problems.
What replaces the simulator is a bench: the real infeed module, the real closed-loop control modules, the real motors, and the real cables, wired on a table instead of inside a machine. Once the bench runs, it becomes both the training rig and the fault-reproduction rig for the machine. The dominant cost is not knowledge - it is cables. A 611A bench that is missing one feedback cable does nothing at all.
Minimum Hardware Inventory for a Two-Motor Bench
A 611A drive group is modular. Two motors means either one two-axis closed-loop control module or two single-axis modules, plus one shared infeed and one shared DC link. Inventory the rack before you buy anything:
| Item | Function | Bench requirement |
|---|---|---|
| Infeed / line supply module | Rectifies the incoming line to the common DC link, supplies electronics voltages, carries the main enable and ready/fault contacts | One per rack. Must be rated for the summed power of both axes for load tests; for no-load spin-up a smaller unit is usually adequate |
| Power module + closed-loop control module (feed axis) | Current/speed control for the 1FT5 servo motor | Matched to the motor current rating |
| Power module + closed-loop control module (spindle) | Main spindle drive control | Spindle control boards differ from feed-axis boards - do not assume they are interchangeable |
| DC link bus bars and jumpers | Links all modules across the rack | Full set, correct lengths, plus the equipment bus ribbon between adjacent modules |
| Blanking / terminating covers | Touch protection on the open end of the DC link | Mandatory - the DC link operates at hazardous voltage |
| 24 V control supply | Enables, contactor control, external logic | Regulated, sized for the rack plus any relays |
| Setpoint source | +/-10 V analog speed setpoint per axis | Precision pot fed from a symmetric supply, a signal generator, or an analog output card |
Cabling: The Actual Gating Item
The most common reason a 611A bench stalls is an incomplete cable set. For each 1FT5 servo motor you need two cables, and for the spindle motor you need two as well:
- Motor power cable - carries the three motor phases and PE from the power module output to the motor terminal box or power connector. On 1FT5 motors with an integrated holding brake, the brake conductors may run in the same cable or in a separate one; check which variant you have before energizing.
- Motor feedback cable - runs from the round 12-pin feedback connector on the 1FT5 motor to the 15-pin D-sub encoder input on the 611A closed-loop control module. This is the cable that is most often missing from a salvaged drive set, and it is not a generic serial cable: pinout, shielding and the shield-to-connector-shell bond all matter.
- Spindle motor power cable - sized for spindle current, usually larger cross-section than the feed axis.
- Spindle encoder cable - from the spindle motor's speed/position encoder to the spindle control module input.
Siemens motion cables carry a 6FX order number printed on the sheath or on a tag near the connector. Record the full number from every cable you own - for example a string beginning 6FX... - before ordering replacements. That number identifies the cable family, connector type and length, and it is the fastest way to confirm whether a cable in a scrap bin is a power cable, a resolver/encoder cable, or something for an entirely different drive family. If the tag is unreadable, photograph both connector faces and count pins: a round 12-pin motor-side connector paired with a 15-pin D-sub is the signature of the 1FT5-to-611A feedback path.
Bench Build and Bring-Up Sequence
Work through this in order. Do not skip the de-energized checks - the DC link stores energy after the line is removed.
- Mount and bus the rack. Modules side by side, DC link bars torqued, equipment bus ribbons plugged between every adjacent module, blanking covers on the open end.
- Bond and earth. Rack backplate to PE, motor frames to PE, cable shields landed at the designated clamp points. Verify continuity with a meter before energizing.
- Restrain the motors. Clamp both motors to the bench plate or a steel frame. A 1FT5 under a step setpoint will move, and a spindle motor with a chuck or coupling stub attached is a projectile hazard. Remove keys and loose couplings.
- Wire control before power. 24 V supply, enable wiring, and the ready/fault contact from the infeed into a lamp or relay so you can see module status. Confirm the exact enable terminal designations for your infeed and control modules from the documentation supplied with the units - terminal numbering differs between infeed variants and between control module generations.
- Set the module hardware configuration. The 611A closed-loop board carries DIP switches and potentiometers for encoder type/pulse count, motor current scaling, speed setpoint scaling, and current/speed loop adjustment. Photograph the as-found switch positions before changing anything, then set them per the module's setting sheet for your motor code.
- First power-up with pulses disabled. Apply line power with all axis enables off. Confirm the infeed reaches ready and no fault LEDs are lit. Measure the DC link only with an instrument rated for it.
- Enable one axis at zero setpoint. With the setpoint pot centered at 0 V, apply the drive and pulse enables to the feed axis only. The shaft should hold position with a slight stiffness, not creep or buzz. Creep means setpoint offset; buzz or squeal means loop gains or feedback wiring.
- Apply a small setpoint. Ramp to roughly 1 V and confirm rotation direction and smooth low-speed running, then increase in steps. Verify the tachometer/actual-value output on the control module follows the setpoint linearly.
- Repeat for the second axis. Commission axes one at a time. Only after both run independently should you enable them together and watch the infeed for overload or DC link overvoltage during simultaneous deceleration.
Verification and Fault Isolation
| Symptom | Likely cause | Check |
|---|---|---|
| No ready, no fault LED, rack dead | Missing 24 V or missing equipment bus link between modules | Measure 24 V at the infeed terminals; reseat every bus ribbon |
| Ready drops the instant pulse enable is applied | Feedback cable open/miswired, or motor phases swapped | Ring out the 12-pin to 15-pin feedback cable pin-for-pin; verify phase sequence at the motor |
| Motor creeps with 0 V setpoint | Setpoint offset or drift offset not trimmed | Short the setpoint input at the module and re-check; trim the offset pot on the control board |
| Audible whine, shaft chatter at standstill | Speed loop gain too high for an uncoupled, low-inertia bench load | Reduce loop gain; remember bench inertia is far lower than machine inertia and will need retuning after installation |
| Runaway on enable | Feedback polarity inverted relative to motor phase order | Kill power immediately; swap feedback polarity or two motor phases per the module setting sheet, not by trial and error |
| Fault only when both axes decelerate together | DC link overvoltage - no braking resistor or undersized infeed for regeneration | Lengthen deceleration ramps or add the pulsed-resistor option appropriate to your infeed |
Log every switch position, pot setting and measured value on the bench. That record is the deliverable: when the drive goes back into the machine, you already know the baseline, and any deviation points straight at the machine wiring rather than at the drive.
When a Bench Beats a Simulator
Three things a bench gives you that no model would: real cable behaviour (shield integrity, connector wear, pin corrosion), real switch/pot semantics on the specific board revisions you own, and real fault-reaction timing on the infeed. Since the 611A commissioning workload is almost entirely hardware setup plus analog trimming, the bench is the simulator - and it doubles as the spares test jig afterwards. Budget the effort where it actually goes: sourcing and verifying the four cables, not searching for software.
Is there any PC software to simulate a SIMODRIVE 611A?
No practical one. The 611A is analog and hardware-parameterized through DIP switches, potentiometers and plug-in option modules, with +/-10 V setpoints and 24 V hardware enables - there is no project file to load or bus to emulate, so a software model would not exercise anything that actually fails during commissioning.
What cables do I need for a two-motor 611A test bench?
Four minimum: a power cable and a feedback cable for each 1FT5 servo motor, plus a power cable and an encoder cable for the spindle motor. The 1FT5 feedback cable runs from the motor's round 12-pin connector to the 15-pin D-sub encoder input on the closed-loop control module.
How do I identify a Siemens motion cable I already have?
Read the order number printed on the sheath or the tag near the connector - Siemens motion cables carry a number beginning with 6FX. If the tag is unreadable, photograph both connector faces and count pins; a round 12-pin motor end with a 15-pin D-sub drive end indicates a 1FT5 feedback cable.
Can I run two motors from one 611A rack?
Yes. The 611A is modular: one infeed feeds a shared DC link, and you add either one two-axis closed-loop control module or two single-axis modules. Size the infeed for the summed axis power if you intend to load-test both simultaneously.
Why does the motor oscillate on the bench but run fine in the machine?
An uncoupled motor has a fraction of the machine's reflected inertia, so speed-loop gains tuned in the machine will be far too high on the bench. Reduce gain for bench work and retune after the drive is reinstalled with the real load.