This is a free browser simulator of the cyclic data between a PLC and a variable frequency drive on Standard Telegram 1. Press Start and the control word goes from 16#047E to 16#047F; the drive ramps up, the status word reports operation enabled, and the two speed words show the setpoint and the actual speed scaled against p2000. Force a fault and the drive will not restart until you send an acknowledge edge on bit 7. Nothing to install, no PLC required.
Run the Simulator
Press Start. Everything on the panel updates the way it would with a real SINAMICS drive on PROFINET.
CONVEYOR 1 · SINAMICS DRIVE
PROFINET · Standard Telegram 1 (PZD-2/2) · simulated
Drive powered up. Press Start — the PLC sends 16#047E first, then 16#047F.
How these bits work →| Control | What it sends | What to watch |
|---|---|---|
| Start / Stop | Sets or clears STW1 bit 0 | The control word switches between 16#047E and 16#047F |
| Speed slider | Writes the speed setpoint to %QW258 | 16#4000 appears at 1500 rpm — 100 % of p2000 |
| Force fault | Nothing — this is the drive tripping | ZSW1 bit 3 turns red, the drive coasts, the motor stops |
| Reset | A 220 ms pulse on STW1 bit 7 | Bit 7 flashes once, the fault clears, and Start must be pressed again |
-
16#047Eis the ready state;16#047Fruns the motor. - "Running" is ZSW1 bit 2 from the drive, never your own run command.
- Fault acknowledge is an edge on bit 7, not a held signal.
-
16#4000in the setpoint word means 100 % of p2000.
The Four Words on Screen
Standard Telegram 1 exchanges two 16-bit words in each direction, every bus cycle. The addresses below are the ones TIA Portal typically assigns; yours come from the drive's Device overview.
| Address | Word | Direction | What it carries |
|---|---|---|---|
%QW256 | STW1 | PLC → drive | Control word: run, enables, acknowledge |
%QW258 | NSOLL_A | PLC → drive | Speed setpoint, 16#4000 = 100 % of p2000 |
%IW256 | ZSW1 | Drive → PLC | Status word: ready, running, fault, warning |
%IW258 | NIST_A | Drive → PLC | Actual speed, same scaling as the setpoint |
Every bit of both words is explained in SINAMICS G120 STW1 and ZSW1: Every Control and Status Bit, and the other telegrams are compared in G120 Telegram Selection in TIA Portal.
What Happens When You Press Start
The drive has a state machine, and the PLC has to walk it through in order. The simulator enforces that order, which is why the control word passes through the ready value before the run value.
| Step | Control word | What the drive does | Status word tells you |
|---|---|---|---|
| Power on | 16#0000 | Nothing — no telegram yet | Switching on inhibited (bit 6) |
| PLC in run | 16#047E | Ready, waiting | Ready to switch on (bit 0) |
| Start pressed | 16#047F | Ramps up to the setpoint | Operation enabled (bit 2) |
| At speed | 16#047F | Holding the setpoint | Speed within tolerance (bit 8) |
| Stop pressed | 16#047E | Ramps down on the deceleration time | Operation enabled drops when the pulses go |
| Fault | 16#047E | Coasts, pulses off | Fault active (bit 3) and switching on inhibited |
| Reset pressed | 16#04FE for 220 ms | Clears the fault | Fault bit goes, ready returns |
Fault and Acknowledge
Press Force fault while the motor runs. The drive coasts, ZSW1 bit 3 turns red and switching on inhibited appears. Now press Start: nothing happens. That is deliberate.
Press Reset and watch STW1 bit 7. It lights for about 200 ms and drops again. A rising edge clears the fault; a reset button held high would hide a fault that keeps coming back and let the motor restart into the same problem. A short fixed pulse also survives the difference between the PLC scan and the PROFINET update time.
Speed Scaling
The drive does not receive rpm. It receives a normalised number where 16#4000 — 16384 — means 100 % of the reference speed set in parameter p2000. Move the slider and compare.
| Speed | Setpoint value | Hex | Share of p2000 |
|---|---|---|---|
| 0 rpm | 0 | 16#0000 | 0 % |
| 375 rpm | 4096 | 16#1000 | 25 % |
| 750 rpm | 8192 | 16#2000 | 50 % |
| 1125 rpm | 12288 | 16#3000 | 75 % |
| 1500 rpm | 16384 | 16#4000 | 100 % |
If p2000 on your real drive is 3000 rpm rather than 1500, every value in the table means twice the speed. Getting p2000 wrong is the most common reason a commissioned drive runs at the wrong speed.
What It Does and Does Not Model
The simulator is a teaching model. It is accurate about the bits, the sequence and the scaling, and deliberately simple about everything else.
| The simulator does | The simulator does not |
|---|---|
| Build STW1 from the 16#047E base pattern | Talk to a real PLC or a real drive |
| Enforce ready before run, and an edge on acknowledge | Model every PROFIdrive state transition |
| Scale the setpoint and actual speed against p2000 | Show current, torque, power or fault numbers |
| Show all 16 bits of both words live | Simulate ramp parameters, limits or data sets |
To build the real thing in TIA Portal, see G120 PROFINET Standard FB for the function block and Siemens PLC and VFD networking for the other ways a PLC can reach a drive.
Do this on real SINAMICS hardware
Run a G120 over PROFINET, build the control block and commission it with a trainer beside you. Pune classroom or live online.
Five Things to Try in the Simulator
Practice- Scroll back to the panel and work through them in order — each one takes under a minute.
- Good as a warm-up before a classroom session, or as homework before a commissioning job.
Produce 16#047E without starting the motor
Load the page and read the control word before touching anything. This is the ready state every PLC should reach first.
Make the setpoint show 16#2000
Move the slider until the speed setpoint word reads 16#2000. The speed will be 750 rpm — half of p2000.
Catch ZSW1 bit 8
Start the drive and watch the status word while it ramps. Bit 8 only lights once the actual speed reaches the setpoint.
Prove the fault interlock
Press Force fault while running, then press Start. Nothing happens until Reset is pressed — that is the restart interlock.
See the acknowledge edge
Press Reset and watch STW1 bit 7. It lights for about 200 ms and drops again; holding a reset button would never clear a repeating fault.
You understand the telegram if you can say, without looking, what 16#047E and 16#047F mean, which bit tells you the motor is really running, and what the drive does with 16#2000 in the setpoint word.
Frequently asked questions
What is this PLC to VFD simulator?
It is a browser demonstration of the cyclic data a PLC exchanges with a variable frequency drive on PROFINET Standard Telegram 1. You press Start, set a speed and watch the control word, status word and both speed words change exactly as they would with a real SINAMICS drive.
Do I need TIA Portal or a PLC to use it?
No. It runs entirely in the browser, with nothing to install and no login. It is a teaching model, not a connection to real hardware.
Why does the control word show 16#047E before the motor starts?
Because bits 1 to 6 and bit 10 must be held at 1 for the drive to be runnable at all. That pattern is 16#047E, the ready state. Adding bit 0 makes it 16#047F and the motor starts.
Why must I press Reset before starting again after a fault?
The simulator copies the restart interlock every safe drive program should have: after a fault the run command has to be released and given again, so acknowledging a fault never restarts a motor on its own.
What does 16#4000 mean in the speed setpoint?
It is 16384, the normalised value for 100 % of the drive's reference speed p2000. If p2000 is 1500 rpm, then 16#4000 means 1500 rpm and 16#2000 means 750 rpm.
Does this work the same on PROFIBUS?
Yes. The telegram and the bit meanings come from the PROFIdrive profile, so STW1 and ZSW1 behave identically whether the drive is on PROFIBUS DP or PROFINET. Only the addressing differs.
Can I use this in my own training session?
Yes — open it on a projector and let the class drive it. If you want a session on real SINAMICS hardware afterwards, Softwell runs those in Pune and online.