Hello everyone,

I'm in need of your help for the following problem.

We have a customer for which we have done 5/6 machines, all copied and pasted from the 1st. They have an S71500 CPU and a S120 CU 320 with 3 single motor modules. The 3 axis are controlled with technology objects, 2 positioning axes and 1 speed axis, using telegram 30 and 105 for all 3. We used TIA17 and motion control v4.0 and I commissioned the last one a couple of weeks ago. CU firmware was 5.1. So far so good, no problems.

For the last one we changed some stuff because of delivery times, so we now have new S71500 CPU type(TIA18 HW catalog), a double motor module and a single one. Positioning axes on the double and speed axis on the single, same telegrams. TIA 18 and motion control v7.0. I also updated the CU's firmware to the latest.

So my problem on the new machine is this, after commissioning the drives (one button tuning and all), I can control them perfectly from their control panel, but as soon as I enable them on the PLC tech object's control panel they start running at maximum speed, when all I'm doing is trying to do the "set home position". I have attached some screenshots of the control panel, telegrams and axis configuration.

The speed axis behaves correctly, so I was thinking that something has changed from MC4.0 to MC7.0. Is telegram 105 not good anymore for positioning axis? Do I have to set the drive in basic positioner mode? It seems strange that when the motor is rotating, the encoder of the tech object does not change. All parameters are the same between TIA17 and TIA18 machine, execpt the new ones of course.

Sorry for the long-winded explanation, I just hope it can be helpful.

Thank you

Found the problem.

Seems to be a Siemens' bug. The pronblem disappeared when I removed the "Invert drive direction" option from the technology objects.

I switched CW e CCW in the drives and used the TO without inversion.