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PFM frequency


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I'm fairly new to DeltaTau motion controllers so please forgive my possibly simple questions.


I have to use an ACC-24E2S card to control stepper motors via an external amplifier. I configured the system for step&direction out put with the encoder loop closed internally as there is no separate encoder according to the basic setup that was posted here in the forum. This allowed me to drive the motor with the online jog commands. When I scoped the pulse train on the Phase D output of the card, I found a frequency of 32kHZ which is way to fast for our application. In reading the reference manuals, I thought that Gate3[0].Chan[0].Pfm together with Gate3[0].PfmClockDiv should control the frequency of the pulse train. Which it didn't.

Luckily I found that the online jog command is solely governed by the Motor[x].JogSpeed variable which has a default value of 32 mu/ms and hence the 32kHz.

I then moved on to create a simple linear coordinate system with one motor and writing a simple motion program that moves the motor absolute to a position, waits a couple of seconds and then returns. Here I found that the default speed seems to be 1 coordinate system unit per second no matter what the value for the PFM or jogspeed is. Entering a different speed F5 changes the speed accordingly.

Now I'm wondering if and when the values for Gate3[0].Chan[0].Pfm and Gate3[0].PfmClockDiv will affect the frequency of my pulse train to the amplifier?

Any answers will be greatly appreciated

Thank you - Andre

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The Gate3.PfmClockDiv register puts an upper limit on the pulse frequency that can be generated – with an absolute limit of 1/4 of the PFM clock frequency. The actual output is through whatever is writing to the Gate3.Chan[j].Pfm register either through an on-line “out” command or a controlled jog move the jog speed parameters or a motion program using the feedrate specification.
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