Operating System: Windows 10

TIA Version: TIA Portal v16 Update 1

To reiterate the subject: I'm trying to use PLCSIM to simulate a PLC with a Kinematic Object (Cartesian portal 3D), with all Positioning Axes virtual and simulated. Almost every attempt of this ends in the PLC going into stop with the following error:

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Description: 

Help on error:

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The kinematic object and it's axes are the only elements of the otherwise empty project. The problem occurs both with Motion Control 4.0 and 5.0 objects. The problem occurs with different PLCs (I tested S7-1504 Drive Controller, S7-1516TF and S7-1517TF). The problem does NOT seem to occur when I make an identical project in TIA Portal v15.1, with Motion Control 4.0 objects. The problem eventually occurs when running the Siemens application project from https://support.industry.siemens.com/cs/document/109755891 upgraded to TIA v16 - although it does seem more stable, and I even managed to get a few manual moves in before it errored out.

Does anyone else have this problem, is there any solution? Is it only related to using PLCSIM, or should I be worried that  I'll be dealing with this when I get the PLC for my current project?

Thanks for Your reply!

However, I'm not convinced that this particular excerpt explains my problem. When I checked the manual for PLCSIM v15 (same link, just use the drop down list to choose v15) You can find exactly the same text under chapter 7.2.6. And, as I have previously noted, I tested the same project created in TIA v15.1 (as in, I used the same steps to create 3 positioning axes and one kinematic object) and did not encounter this OB91 buffer overflow error when changing the PLC to run, or when going online, or when opening the kinematic object commissioning interface, or finally when moving the simulated kinematic object - in contrast to TIA v16, where any of these actions usually resulted in the error.

Somebody might find this informations helpful as well: 

In PLCSim Advanced (i now use V5.0 Upd1) there is an checkbox called "Strict Motion Timing". The manual quotes: 

"Here you disable the overrun detection for Motion Control (OB MC-Servo [OB91]). When the check box is selected (default), overruns are detected."

I ran into this issue when i tried to use breakpoints and were all the time getting the overflow OB91 message as soon as the motion cycle time exceeded (which makes sense). When you deactivate the checkbox in PLCSimAdvanced, no overruns are detected and breakpoints are working

Hi there,

I feel that quite some things have been mixed here.

For one, PLCSIM (which means the regular one as well as Advanced) only simulates the behavior of the PLC, not the timing. The manual also states this.
One result of this can be overflows of OB MC-Servo. But it is not restricted to this OB, it could also happen to other OBs that get called in some cycle, like a cyclic interrupt OB. The main difference between these simply is, that MC-Servo by default (and not changeable) throws this error, while the other cyclic OBs by default do not (but can be switched on in their settings). So by default, you just don't see the issue there, while it might be present there, too.

The other thing is the TO versions:
There is not really a difference there between the TO versions and the behavior of the OB in PLCSIM. The differences come from the PC used, the OS used on this PC, the other programs running in parallel to PLCSIM (as this might influence the performance of PLCSIM, because the PC has to run all this in parallel), and the version of PLCSIM.

Which brings me to the last point, the versions of PLCSIM:
Yes, there are differences. For some time (I think it was PLCSIM Advanced V2 and the corresponding version of PLCSIM), the overflow was simply not thrown as an error. So you did not have the error, but still had the issue. If you simulated and wanted to really simulate your motion, you only saw the effects of the overflow, but not the overflow itself; in the end you had strange effects, but did not really see why.
Then some newer version of PLCSIM (I think from V3 onwards) threw this exception (just like the regular PLC always did). And since PLCSIM Advanced V4 there is the "Strict motion timing" checkbox. If you deactivate it, the error about the overflow will not be thrown (to have the PLC continue running); but then you are basically back with not seeing the error but still having the issue! So only use this, if simulation of motion control is of no interest for you! In other cases, set the checkbox.

So what to do if you want to simulate motion and run into this error?
-> close not necessary software on the machine while simulating, if a VM is used allocate more ressources (CPU), if Notebook is used set power settings to the most performant setting, if you use PLCSIM Advanced then use the virtual time scaling (left is the right direction), and if none of this helps, increase the cycle time parametrized at the MC-Servo OB, until the issue is gone.

And for the last comment about breakpoints:
Breakpoints in the PLC program cannot be used, when motion control is used. Otherwise, the overflow of MC-Servo will appear. Not nice, but it's the way it is. So in this scenario, disabling the "strict motion timing" in PLCSIM Advanced might actually be a good solution, if you don't care about motion in the simulation. But on a real PLC you do not have this checkbox, so there breakpoints will result in the overflow, if MC-Servo (and therefor motion) exists on the PLC.

Regards,
daviso