BUR

For PMAC 2 the DAC output appears to be X:$0049. According to the manual the DAC value should be a 16 bit value. How can I decode the hex value in that register to get the actual DAC-value? Trying to gather it with Quick plot leads to very small values (like 0.0544...), while the register contains a big value like $FF5210. What I actually expect is a value between -32767 and + 32767.

Thank you for this very comprehensive reply!

Apparently it is limited, depending on how much is to be calculated within a servo cycle. Setting the I900 to low could yield that the calculations cannot be finished by the time interrupt. This might also depend on how many axes have to be calculated or if PLC programs are running. Is there a rule, what maximum frequency I can get? How do I realize, I have set the freq. to high?

Now I just type: P70=..... ; start frequency [Hz] P71=..... ; stop frequency [Hz] P85=....; ; sweep time [ms] del gat def gat 34500 ena plc 4 After capturing I go to PMAC PLOT and press 'upload data' which will take a while and then 'plot data'. So I'll finally have my desired data set. Thanks, problem solved BUR

As I understand the servo cycle frequency is set with the parameters I900 and I902. The default value of I900=6527 would limit the servo cycle frequency to 9034.6 Hz. However a I900 set to 0 would enable a servo cycle frequency of 39.3 MHz? Is that possible? What would be the reasons for limiting it then?

It works now. I use a program like that, where I only have to change the four sweep parameters: ; Initiate sweep definition ; #################################################### CLOSE DELETE GATHER P70=1 ; start frequency [Hz] P71=10 ; stop frequency [Hz] P80=400; ; sweep magnitude [cnt] -> 100 nm P85=1000; ; sweep time [ms] ; Set addresses ; #################################################### M88->X3,18 ; Data gather prep bit M89->X3,19 ; Data gather on bit M0 ->X0,24 ; Servo cycle counter (=timer) M85->X$07F0,24 ; Memory allocation for start time M86->X$07F1,24 ; Memory allocation for elapsed time M81->D$0028 ; #1 cmd position register ; Setup gathering variables ; #################################################### I19=1 ; gather each servo cycle I20=3 ; gather two variables I21=$800028 ; gather cmd position I22=$80002B ; gather act position I45=0 DEFINE GATHER 20000 ; prepare data buffer for gathering ; #################################################### OPEN PLC 4 CLEAR CMD"GAT" ; Start data gathering P99=1 ; one pass while loop While (P99=1) ; to address gathering delay P99=0 EndWhile P75=P85/LN(P71/P70) ; calcutate time constant P76=360*P70/1000; ; calculate omega 0 P81=P80*I108*32 ; amplitude inkrement (position register) P86=P85*8388608/I10 ; sweep time in servo cycles P82=M81 ; current commanded position M85=M0 ; start of the timer M86=M0-M85 ; time elapsed so far in servo cycles P87=M86*I10/8388608 ; time elapsed in ms P72=P76*exp(P87/P75) ; current omega M81=P82+P81*sin(P72*P87); update position While (M86 < P86) M86=M0-M85 ; time elapsed P87=M86*I10/8388608 ; time elapsed [ms] P72=P76*exp(P87/P75) ; current omega M81=P82+P81*sin(P72*P87) ; update position EndWhile DISABLE PLC 4 ; CLOSE ; #################################################### I5=3;

Is that because the PLC program starts anew after execution, before it is cancelled by the DISABLE command and so the buffer would be initialized twice and the data cannot be captured? If so, what can I do against it? Or is there another reason for my capturing endeavor to fail? What goes wrong?

The aim is actually to define several sweeps in different frequency ranges to obtain transfer functions, which can be concatenated. But then for the higher frequencies one needs to make the sweep time quite short in order to enable a storage of the full response.

Now I tried it with a step response program. The program looks like: _____________________________________________________________ ; Setup and Definitions ; ################################################ CLOSE P80=1000; ; step size in counts M88->X3,18 ; Data gather prep bit M89->X3,19 ; Data gather on bit M0 ->X0,24 ; Servo cycle counter (=timer) M85->X$07F0,24 ; Memory allocation for start time M86->X$07F1,24 ; Memory allocation for elapsed time M81->D$0028 ; #1 cmd position register ; Setup Gathering variables ; ############################################### I19=1 ; gather each servo cycle I20=3 ; gather two variables I21=$800028 ; gather cmd position I22=$80002B ; gather act position I45=0 ; ############################################### OPEN PLC 2 CLEAR CMD"DEL GAT" CMD"DEF GAT 20000" CMD"GAT" ; Start data gathering P81=P80*I108*32 ; step time P86=P85*8388608/I10 ; step time in servo cycles M81=M81+P81 ; increment the commanded position M85=M0 ; start of the timer M86=M0-M85 ; time elapsed so far While (M86 < P86) M86=M0-M85 EndWhile M81=M81-P81 ; now decrement commanded position again M85=M0 ; Restart timer M86=M0-M85 ; Time elapsed While (M86 < P86) M86=M0-M85 EndWhile CMD"ENDGATHER" DISABLE PLC 2 ; CLOSE ; ############################################### I5=3; ____________________________________________________________ Now typing LIST GATHER on the shell, there will be just 2 hex numbers. Using the same settings be online command data gathering, following: DELETE GATHER DEFINE GATHER 20000 GATHER ENDGATHER LIST GATHER I will get the values out. Now I can even export them by PMAC PLOT, what I found, by simply pressing on 'upload'. But then I don't have the step response. Why won't that work for the PLC program? The step response is indeed carried out by the drive (a little click noise), but the data are not captured correctly.

Yes, this should be possible.

On the other hand there is the PMAC Plot tool, where I can gather data at any desired capturing rate and time range, but there I cannot initiate a commanded sweep simultaneously. I found that program for getting a step response. But then I cannot read the data out at the end, even though they were captured. SIZE returns 34546 at the beginning. Then I capture 10000 values, so SIZE would return 24546. For capturing I set: I19=1 I20=3 I21=$800028 I22=$80002B I45=0 DELETE GATHER DEFINE GATHER 10000 GATHER or CMD "GAT" ... ENDGATHER or CMD "ENDGAT" Now the data are captured. But how to get them into a file? I will be able to transform the hex data into counts surely, once I have them I a file, but how to? Copy and paste from the terminal is not working.

Hello, I am working with a PMAC2 control, using the PMAC Executive Suite 3.2 for communications. My objective is to get a transfer function of the controlled (closed loop) system, obtained by frequency sweeps. The PMAC TuningPro software includes a possibility to sweep, but it is: 1. limited to 225 Hz (servo loop cycle is 9.0346 kHz) 2. limited to integer numbers for the time range 3. not permitting any control of the capturing rate My questions are related to these problems: Can I manually change the deposited programs for these kind of motions? Where can I find them? How can I gather data from terminal, plotting them into a file? The LIST GATHER command only plots them in the terminal, where I am unable to save them for further processing.