Digital output PWM resolution V3.0 vs V4.0 and above

Hello,

I have relatively old 1212C DC/DC/DC CPU from 2014 (6ES7 212-1AE31-0XB0) with V3.0 Firmware.

I am trying to configure PWM output on Q0.2 (PWM2 Pulse generator).

It works, but with relatively low physical resolution at the output.

For example: with 10ms cycle time (100Hz), I can set the physical pulse width (monitored with oscilloscope at the output Q0.2) just as an integer number of milliseconds: 2, 3 and so on.

Regardless of the pulse duration format (I use Thousandths), I cannot get 2.5 ms pulse at the output when I write 250 into QW1002 output word address. 220, 230, 299 makes no difference at the output. When I write 300, it jumps from 2ms to 3ms pulse width. It looks like a physical resolution of the output is limited to 1ms, and in order to get 1% discretization I need to set the frequency to 10Hz (100ms cycle), which is too low for my application.

Question: is it a limitation of this old hardware or maybe I am doing something wrong in the configuration?

If I take most actual hardware, 6ES7212-1AE40-0XB0, what physical resolution at the Q0.2 output can I expect?

Thanks

Thank you Jacek

That was exactly the problem.

I have just changed the time base to microseconds and it works as expected.

So, the time base is the clue, not the hardware...

Regards,

Sergey