Using s7-1215 for machine tool

Hi. I have CPU 1215C DC/DC/DC with signal board DI4x5VDC/200 kHz (6ES7 221-3AD30-0XB0). I wanna use it for controlling 2 axis machine tool. I tried to control stepper drives using PTO output with motion control v6 library. I saw manual, and downloaded examples. Everything works good.

But i have manual handwheel, which connected to high speed counter. I know how to use block CTRL_HSC for this counter, it works. But i need to use handwheel for manual moving any of 2 axis in machine tool. I tried to use blocks MC_MoveRelative or MC_MoveAbsolute applied counted pulses to "Position" input, but this blocks are working only when positive edge appears on "Execute" input. But application requires real time step by step movement (for example 1, 10, 100 micrometers and it measured by measurement scale, connected to 5v signal board). It means, that PTO output must repeat pulse sequence of manual handwheel.

I hope you can help me to solve this problem. I'm sorry for my English

Hello,

it would be possible to generate a positive edge on "Execute" input, when there is a deviation between

counter and position setpoint.

Maybe when deviation > 5 , you generate a new edge.

_reso_

Hi. I have CPU 1215C DC/DC/DC with signal board DI4x5VDC/200 kHz (6ES7 221-3AD30-0XB0). I wanna use it for controlling 2 axis machine tool. I tried to control stepper drives using PTO output with motion control v6 library. I saw manual, and downloaded examples. Everything works good.

But i have manual handwheel, which connected to high speed counter. I know how to use block CTRL_HSC for this counter, it works. But i need to use handwheel for manual moving any of 2 axis in machine tool. I tried to use blocks MC_MoveRelative or MC_MoveAbsolute applied counted pulses to "Position" input, but this blocks are working only when positive edge appears on "Execute" input. But application requires real time step by step movement (for example 1, 10, 100 micrometers and it measured by measurement scale, connected to 5v signal board). It means, that PTO output must repeat pulse sequence of manual handwheel.

I hope you can help me to solve this problem. I'm sorry for my English

Dear _reso_,
Here I share with you a S7-1200 handwheel application I developed for a Circular Saw Blade Sharpening Machine in 2010, using the first version of TIA Portal (TIA V10.5) with S7-1200 FW1.0. I have spent a few hours to extract the handwheel part from the original project, and migrate it gradually from TIA V10.5 to TIA V14 SP1 and tested. I think you are able to migrate it yourself to TIA V15 without problem, if you are already using this latest version of TIA Portal.
The attached application example has been tested with a real CPU 1215 FW4.2 myself. The logic is simple and effective, I think. Please spend a little bit of time to read through the codes. It's quite short. I don't create a document for you. Instead, I'll explain you a little here.
This application example is for two axis, and, very easily can be expanded to the maximum axis the CPU supports. Just create more MC_MoveRelative instructon for each Axis in FB1 Handwheel_Drive.

• FC1 Handwheel_Diff: counts the increment of handwheel pulses via HSC, output CNT. FC1 is called in Cyclic interrupt_Diff (OB200) with 50ms cycle time (adjustable, effect will be explained later)
• FB1 Handwheel_Drive: multiplies the increment (FC1 output CNT) by the handwheel Ratio switch (x1/x10/x100) and send the pulses out via MC_MoveRelative. FB1 is called in Cylcic interrupt_Drive (OB201) with 1ms cycle time (increase the cycle time, if the OB suffers a time overflow error).
• The input parameters of FB1 is described in the FB interface's Comment column. You should assign the correct handwheel physical wiring to the FB (feel free to change them to fit your real situation).

In this example, the Mechanics of TO, 10,000 pulses=10mm, means 1pulse=0.001mm, so you must set 0.001 to the parameter 1Pulse=?Unit for FB1.
The parameter Velocity of FB1 indicates how fast you want to send the pulses out. If set too high, the Axis will follow tightly the handwheel, but may cause vibration. If set too low, the Axis will keep running even you stop turning the handwheel, till finished sending all of the pulses out. A half of Axis maximum velocity is recommended. The Acceleration/Deceleration of the Axis (assign in TO or overwrite in user program) also affects the handwheel's behavior in the same way.

Effect of Cyclic interrupt_Diff (OB200) cycle time: for example,

• 10ms: Axis moves very smoothly in ratio x100, very low vibration, but in ratio x1 handwheel pulses might be lost. Means, for example, you rotate one turn of handwheel (100 pulses) but less than 100 pulses will be sent to Axis. Even so, this will not affect the actual real position of the Axis; just handwheel pulses not counted. In practice, the operator will not actually be aware of how many pulses he has already produced with handwheel.
• 50ms: Axis moves smoothly in ratio x100, low vibration, pulse lost only if you turn very slowly the handwheel
• 500ms: Axis vibrates in ratio x100, but without losing pulse.

Conclusion: for Cyclic interrupt_Diff (OB200),
Smaller the cycle time, more smooth, but more possibly lose pulses.
Greater the cycle time, more vibration, less possibly lose pulses.
Please try different cycle time, feel and adjust yourself.

For HSC, don't forget to set the input filter as smaller as possible (ex. 0.1 microsec).
I suggest you to test first this application example with the same wiring as defined in the PLC tag table, and combined it later into your project, if you satisfy with the result.
Hope this application example can be helpful to you.
Best regards,
Yu-wen

Dear Yu-wen Tang,

Thank you for your help. As you said, migration to TIA v15 was successful. Code real simple, i tried almost the same way. But all blocks of motion control library (MC_absolute, MC_realative, MC_velocity) have a problem. All of them working after appearing positive edge at the "Execute" input. After that it working with acceleration/deceleration ramp and you can observe it on PTO traces. It leads to stick-slip motion, which can damage mechanics. Ideal way will be to set outputs directly, depending on HSC input states. 

Even if i change cycle time it cant prevent stick-slip motion. I think the reason of it can be losing of pulses. 

Mister T

Hello,

did you think about using motion control function "MC_MoveJog"? With this function you could start motion with positive edge at direction input "JogForward" or "JogBackward". While one of these inputs is set, you could change the velocity of movement with a new value at intput "velocity".

Now you have to calculate the set-velocity of your handwheel in every cycle and write this new value to the Input "velocity" of "MC_MoveJog". But be careful with the calculated velocity. Do not start the function with a calculated velocity higher than a given maximum velocity and stop the motion control function if the calculated velocity is lower than a given minimum velocity.

The problem is to get these minimum and maximum velocity to start or stop the motion control function.

Maybe this decision will help...

 Hello. Thank you for your advice about MC_Movejog. But how i will check, that only one pulse of handwheel was transfered to PTO output? Application requires fine motion, contolled by measurement scale, step of movement must be 25 micrometers.

Hi Yu-wen Tang.

Your decision of my problems works pretty, as you said. But at x10 and x100 ratio losing pulses. I don't know how to solve it. Real position differs from handwheel position. I tried to change OB 200 cycle time, but problem exist. Thank you very much for your advices.