george.kontogiorgos

March 7, 2022

Hi moha_sa,

I'm currently working in a fast data acquisition application using native gather inside a C Background Program.

On 3/1/2022 at 8:24 PM, moha_sa said:

I tried "fprintf" but it does not seem generating any text file anywhere in the program folder on windows.

The Background Program runs on Linux, inside the controller. If you are trying to write some file, the fopen path argument (to create a file handler for fprintf, where it will write to) must exist on controller's Linux, not on Windows where IDE runs. Are you checking fopen's return value?

/*For more information see notes.txt in the Documentation folder */
#include <gplib.h>

#define _PPScriptMode_		// for enum mode, replace this with #define _EnumMode_
#include "../../Include/pp_proj.h"

int main()
{
  FILE * fp;

  fp = fopen ("/var/ftp/gather/file.txt", "w+");

  // Check if file handler is not corrupted
  if(!fp)
  {
    printf("Error trying to open the file, is everything ok?\n");
    return -1;
  }

  fprintf(fp, "%s %s %s", "Write", "some", "stuff");

  fclose(fp);

  printf("File was written successfully!\n");

  return 0;
}

This snippet is a simple file writer that check it. Connect to the controller via SSH, run the above program and check if /var/ftp/gather/file.txt was created correctly after "File was written successfully!" message from the program. Now you can use pscp (Windows) or scp (Linux), or another tool, to copy the file to your Windows host where IDE is running. A strong evidence that there is something wrong with the path argument is fopen returning NULL value.

Besides that, the IDE program folder isn't synchronized with controller's folder when you Download the project, it's just a copy (to /opt/ppmac/usrflash/Project). Also, the project folder inside Power PMAC is write protected and you may modify the permissions to write to it (Honestly I don't like this idea).

On 3/4/2022 at 9:46 PM, AAnikstein said:

That said, as somewhat of an excerpt, we have used code that looks roughly like this:

If you want to have some more control to the gather process (and complete AAnikstein's code) I did some manipulation with fork and file descriptors:

// Create gather process
pid_t pid=fork();

/* Child process */
if(pid==0)
{
  // Open gather output file
  int gather_file_fd=open(file_path, O_WRONLY | O_CREAT, 0777);
  if(gather_file_fd==-1)
  {
    return 2;
  }

  // Make stdout of gather program as input of output gather file
  int gather_file_fd_dup=dup2(gather_file_fd, STDOUT_FILENO);
  close(gather_file_fd);

  // Give this process to gather control, like a parasite
  int err;
  err=execl("/usr/bin/gather","gather","-w",NULL);

  if(err==-1)
  {
    return 2;
  }
}
else
{
  /* Parent process */
  return pid; // Return child PID
}

Doing that you are changing the gather output from stdout to the file and also you have the PID of the gather program instead of system command that do not allow you to manipulate gather process.

Regards,

George

February 23, 2022

Hi Eric!

Thanks for replying me.

12 hours ago, Eric Hotchkiss said:

The CaptCompISR should be as short as is possible.

Yes, I do know that this is a good pratice, thanks for the advice. I think it would not be a problem if the CaptCompISR just enable the gather.

12 hours ago, Eric Hotchkiss said:

The best method would be to set a flag (such as a script global variable), that can be reacted to by a background Script/C PLC.

I had this idea but I was trying to avoid any delay between the interruption and enabling the gather.

February 22, 2022

Hello,

On 2/14/2022 at 8:31 PM, Eric Hotchkiss said:
The "Command" command can be used from C to run code in the script environment after changing these settings.
Command("Gather.Enable=2");

I would like to use it on CaptCompISR routine, is it possible? What is the best way of enabling gather from interruption?

February 16, 2022

Hello

I know that we already have the execution of CaptCompISR function when position matches to the preset value. I would like to set the interrupt source not as position but as some GPIO, User Flag, Hall input or some other hardware IO.

In my point of view the ISR is an elegant solution when compared to polling some input, which is the way I'm thinking to run a program when some input is triggered.

Thanks in advance,

George

February 15, 2022

Hi Eric,

16 hours ago, Eric Hotchkiss said:
The "Command" command can be used from C to run code in the script environment after changing these settings.
Command("Gather.Enable=2");

Thanks for the tip. I was using to circumvent the problem on my API:

GetResponse("Gather.PhaseEnable=2", gpascii_response, 100, 1);

But maybe your command is faster than mine since GetResponse has to manipulate the return from the command.

I was thinking in just initialize Gather. structure on the begining of my program with something like that

// Initialize Gather. struture
Command("Gather.Enable=0");
Command("Gather.Enable=1");
Command("Gather.Enable=0");

// Use gather structure directly
pshm->Gather.Enable=2;

Thanks,

George

February 11, 2022

15 minutes ago, george.kontogiorgos said:

And then the PowerPMAC crashed (the red arrow 😞

The sad Emoji was a mistake made by a set of special characters toghether, I'm sorry about it.

February 11, 2022

Hi Eric,

As your suggestion I did some tests as follows.

Test 1

I issued the folowing commands (on that order) on the terminal:

$$$
Gather.Items=1
Gather.Addr[0]=Sys.ServoCount.a
Gather.Period=1
Gather.MaxSamples=100000

And then I ran my C Background Program with the following content

/*For more information see notes.txt in the Documentation folder */
#include <gplib.h>   

#define _PPScriptMode_		// for enum mode, replace this with #define _EnumMode_
#include "../../Include/pp_proj.h"

int main(void)
{
	InitLibrary();  // Required for accessing Power PMAC library

	pshm->Gather.Enable=2;				//Put your code here

	CloseLibrary();
	return 0;
}

And then the PowerPMAC crashed (the red arrow 😞

Test 2

I reseted the PowerPMAC with $$$, opened the plot window and wait it initialize. After that I closed the plot window and set my gather parameters (Just to be the same as the last test since plot window sets Gather.Period and Gather.MaxSamples when it opens).

Then I ran my C Background Program (the same as Test 1) and everything goes fine.

Conclusions from Test 1 and Test 2

Opening the plot window before using pshm->Gather.Enable=2 on the C Backgroud Program works fine (the PowerPMAC does not crash by enabling gather on a C program). I suspected the Gather.Enable=1 followed by a Gather.Enable=0 that is on plot window Gather Settings area. That was difference from my configuration from terminal and configuration from Plot window. This lead me to Test 3.

Test 3

I did exactly the same as Test 1 but adding Gather.Enable=1 followed by a Gather.Enable=0 on Initial gather configuration on IDE Terminal:

$$$
Gather.Items=1
Gather.Addr[0]=Sys.ServoCount.a
Gather.Period=1
Gather.MaxSamples=100000
Gather.Enable=1
Gather.Enable=0

Then I ran the C Background Program and the PowerPMAC did not crash.

Conclusions from Test 3

PowerPMAC Test 3 lead me to the conclusion that setting Gather.Enable=1 or Gather.Enable=2 (value 2 I tested earlier on my first post of this thread) run some initialization on Gather. structure. So I did Test 4 to know if setting Gather.Enable=0 and run the C Background Program crash the PowerPMAC.

Test 4

I reseted the PowerPMAC controller and then issued the following commands into the IDE Terminal

Gather.Items=1
Gather.Addr[0]=Sys.ServoCount.a
Gather.Period=1
Gather.MaxSamples=100000
Gather.Enable=0

Then I ran the C Background Program and the PowerPMAC crashed.

Conclusions from Test 4

Setting the same value (Gather.Enable=0) to register and running the C program crash the controller. The last test, the test 5, I just tryed the last option for enabling gather (Gather.Enable=3).

Test 5

I reseted the PowerPMAC controller and then issued the following commands into the IDE Terminal

Gather.Items=1
Gather.Addr[0]=Sys.ServoCount.a
Gather.Period=1
Gather.MaxSamples=100000
Gather.Enable=3
Gather.Enable=0 // Stop rotary gather

Then I ran the C Background Program and the PowerPMAC did not crashed.

Conclusion

Changing Gather.Enable value from 0 to something different from IDE terminal may initialize something inner the controller that allow pshm-Gather.Enable works fine on a C Background Program. This is what Plot window does when it initializes (we can see on Gather registers changes). Obviously I do not know in fact what the Plot window does and maybe it do some inner controller initialization.

Thanks,

George

February 4, 2022

Hi wehg,

On 2/1/2022 at 9:05 AM, wehg said:

I'm not having any issues with loosing samples

I did some tests with lower sample frequencies and I didn't had issues with loosing samples too. I was performing gathers using phase interrupt source with 10 kHz of phase frequency and Gather.PhasePeriod=1 which led me to a 10 kHz of sampefrequency. When I used Gather.PhasePeriod>=3 I didn't loose any sample, neither at begining nor ath the end.

Maybe your sample frequency is sufficient slow to don't show this kind of problem (I would appreciate if you could test your setup with higher sample frequencies).

On 2/1/2022 at 9:05 AM, wehg said:

I guess the question becomes: When using gather.enable=3, is the gather_csv utility applicable or usable? And if so, how do you use it in combination with gather.enable=3?

Unfortunately I don't know the exact answer to your question and I would like to know too.

I was searching on the forum some stuff related to gather and Background Programs and I found this. Maybe the best option for us is writting our own gather_csv which manipulates the buffers and files in a way that fits well for our applications.

Regards

George

February 4, 2022

Hello,

I am unsuccessful trying to trigger data gather from a C background program. I wrote the following program (capp1.c) to debug the problem:

/*For more information see notes.txt in the Documentation folder */
#include <gplib.h>

#define _PPScriptMode_		// for enum mode, replace this with #define _EnumMode_
#include "../../Include/pp_proj.h"

int main(void)
{
	InitLibrary();  // Required for accessing Power PMAC library

	pshm->Gather.Enable=2;
	
	CloseLibrary();
	return 0;
}

Then I built, downloaded and save the project. After that I restarted the controller with $$$ on IDE terminal and run my background program via SSH connection (./capp1.out). The controller then suddenly stops responding on IDE and the controller`s watchdog LED lights up.

When I first do some gather via IDE terminal (Configure everhing, Gather.Enable=2 and Gather.Enable=0) , the background program starts working (it sets correctly the enable register and gather the desired data).

I have the hypothesis that the commands issued from terminal do some initialization on gather feature but I do not know how to track it. This idea of initialization comes to me when I realized that when I do Gather.Enable=2 on C program the Gather.Index does not automatically erase as it happens when the same command is issued from IDE terminal. So I manually erase the buffer and reset index as follows:

/*For more information see notes.txt in the Documentation folder */
#include <gplib.h>

#define _PPScriptMode_		// for enum mode, replace this with #define _EnumMode_
#include "../../Include/pp_proj.h"

int main(void)
{
	InitLibrary();  // Required for accessing Power PMAC library

	//Put your code here

  	// Disable any running gather
	pshm->Gather.Enable=0;
  
	// Set sample counter to zero
	pshm->Gather.Samples=0;

  	// Erase buffer with gpascii command (Index points to buffer's position 0 after clear)
	GetResponse("clear gather", gpascii_response, 100, 1);

	// Start gather
	pshm->Gather.Enable=2;

	CloseLibrary();
	return 0;
}

Another point is that I could successfully enable the gather at first time after reset by using:

GetResponse("Gather.Enable=2", gpascii_response, 100, 1);

Instead of:

pshm->Gather.Enable=2;

I tryed on two different controller's architecture:

Type: POWER PMAC BRICK

CPU: PowerPC, AMP86xxx

Firmware: 2.5.4.0

And

Type: POWER PMAC BRICK

CPU: arm,LS1021A

Firmware: 2.6.0.0

Thanks in advance,

George

January 31, 2022

3 minutes ago, wehg said:

What I am trying to do is stream the gathered data to a file in rotary fashion, so that I am not limited by the gather buffer size. So far, I have not been successful with this rotary method.

Hi wegh,

The way I found to circumvent the problem of rotary gather was issuing the following command to the PowerPMAC linux terminal (using pipe):

gather -p -w > "yourfile"

Once gather program armed, using Gather.PhaseEnable=2 to trigger the gather and setting large number on register Gather.PhaseMaxSamples to not reach the end of the file quickly.

At some point I stopped the gather with Gather.PhaseEnable=0 and issued Ctrl+C on PowerPMAC linux terminal. In another test I wait the gather to reach the Gather.PhaseMaxSamples and issued Ctrl+C on PowerPMAC linux terminal. On both situations the gather didn't lose any samples.

Nevertheless, I could not successfully do the rotary gather with the option Gather.PhaseEnable=3.

I also create a custom phase loop to be able to sample the Gather.PhaseSamples register (Setting Gather.PhaseAddr[0]=Gather.PhaseSamples.a is not possible) by assigning its value into a global variable so I can acquire it with PowerPMAC gather tool.

void user_phase(struct MotorData *Mptr)
{
	pshm->P[100]=pshm->Gather.PhaseSamples;
}

For now it solves my problem, but I think that future implementations would be in risk by this limitation of Gather.PhaseEnable=3.

January 20, 2022

Some information about my controller

Type: POWER PMAC BRICK

CPU: PowerPC, AMP86xxx

Firmware: 2.5.4.0

January 19, 2022

Try using the “-u” option instead of the Linux pipe.

Your tip led me to the following error:

10.20.56.18:/opt/ppmac/gather_csv# ./gather_csv -p -w -u /var/ftp/gather/test1.txt
Too many command line arguments.  If using a long file name
enclose it in " " ie. "long filename.txt"
Proper usage :
gather_csv [-p] [-u] [filename]
           -p optionally gather on phase
           -u upload last gathered data
           -w wait until for gather to started
           -r upload last rotary gathered data

Remember that I'm trying to perform a rotary gather and the option -u is used to upload gathered data on buffer. How could be the usage with -r (which is the option for rotary gatered data)?

I would like to keep the option -w, so I could start the gather and take the first samples on a triggered gather for example.

January 18, 2022

Eric,

I think that your suggestion fits on my application for now.

Thanks.

January 17, 2022

Hello,

I'm doing some experiments with data gather system and I relized that the gather program missed some samples.

The pointer Sys.PhaseSamples presented a more samples number than line numbers on the gather text file. The difference is about 20 samples but it is not repetitive for every gather.

The gather setup was did on IDE Terminal as follows:

Gather.PhaseEnable=0
Gather.PhaseAddr[0]=Sys.PhaseCount.a
Gather.PhaseItems=1
Gather.PhasePeriod=1
Gather.PhaseEnable=1
Gather.PhaseEnable=0
Gather.PhaseMaxSamples=500000

After I issued the gather program with wait option on Linux:

./gather_csv -p -w > /var/ftp/gather/test1.txt

Triggered the rotative gather on IDE Terminal:

Gather.PhaseEnable=3

After some time, usually when Gather.PhaseSamples > Gather.PhaseMaxSamples (To check the rotative buffer), I stopped the data acquisition:

Gather.PhaseEnable=0
Gather.PhaseEnable=1
Gather.PhaseEnable=0

The last gather gave me Gather.PhaseSamples=32818200. The first line of data acquisition file test1.txt (After Waiting to phase gather) is 71693224 phase counts and the last line of the same file is 104511413 phase counts. The difference is 32818189, so threre are 32818190 samples because we have to take the first line in account. So this data acquisition lost 10 samples this time.

I don`t know if there is any delay on the gather system at the begining or at the end of the acquisition due to initialization or finalization of the program respectively and this lead to missing some samples.

The difference between one sample and another is 1 in every line (I tested it with a Python script), according to Gather.PhasePeriod=1. This led me the conclusion that these lost samples are not at the middle of the gather.

I would like to know why I`m losing samples and understand it to set up things correctly for future applications.

Thanks in advance.

January 17, 2022

Hello

I would like to know if there is a way to share variables (e.g. Global Variables) between PowerPMAC Script Language and embedded Linux on controller.

Actually, I was unsuccessfully trying to create a C program and compile it with GCC to access the content of a Global Variable address as the example as follows:

#include 
#include 

int main()
{
 int * pointer;

 pointer = 0xa9304b20;

 printf("%d\n", *pointer);

 return 0;
}

Where

Sys.P[100]=$a9304b20

The program crashed by Segmentation Fault error and I'm searching for new ways to access these variables on the memory by Linux.

April 26, 2021

Hi Smakarem,

Thank you for the information.

Maybe my manuals are not the latestest and it does not appear on there.

April 9, 2021

Hello,

I have to report the position of a single encoder through a motor structure without InPos and DacLimit problems due to absence of feedback signal. So I was trying to create a second reference signal (Apart from DesPos signal) to input an EncTable structure pointed to the single encoder (without motor). So I was performing some tests with virtual motors modifications to attempt this second reference signals by the following snippets of code:

EncTable[31].type=1 // 32-bit register read
EncTable[31].pEnc=Sys.Idata[9].a // Same as Motor[5].pDac
EncTable[31].pEnc1=Sys.pushm // Dummy read (not used)
EncTable[31].index1=0 // No shift right of source data
EncTable[31].index2=0 // No shift left of source data
EncTable[31].index3=0 // No accel limiting
EncTable[31].index4=1 // Single integration
EncTable[31].PrevDelta=0 // No bias before integration
EncTable[31].MaxDelta=0 // No velocity limit
EncTable[31].ScaleFactor=1/65536 // 32 bits -> 16 bits

EncTable[32].type=9 // 32-bit register read
EncTable[32].pEnc=EncTable[31].PrevEnc.a // Same as Motor[5].pDac
EncTable[32].pEnc1=Sys.Idata[10].a // Same as Motor[5].pDac
EncTable[32].index1=0 // No shift right of source data
EncTable[32].index2=0 // No shift left of source data
EncTable[32].index3=0 // No accel limiting
EncTable[32].index4=0 // Single integration
EncTable[32].MaxDelta=0 // No velocity limit
EncTable[32].ScaleFactor=1 // 32 bits -> 16 bits

Motor[9].pEnc=EncTable[32].a

When I set

Sys.Idata[9]=1

I would expect that the motor 9 position start running to infinite since Index4 of EncTable[31] is 1 and so it perform a single integration. When I set

Motor[9].pEnc=EncTable[31].a

The motor 9 position behave as I expect (incrementing due to integration).

I suppose that PrevEnc ignore the integration (as it does with ScaleFactor) but I just find this behaviour with ScaleFactor on software manual.

I would like to know if my hypothesis is correct.

March 10, 2021

Hi,

I am trying to add a custom folder on powerpmac project. I modified the .ppproj to include the custom folder (named step-scan) and it works as I could see it on my project (see figure 1 attached).

However I could not find the PLC's declared variables by query them on terminal and the PLC name could not be found.

My PLC was dowloaded as I could see it inside these folders:

./.readonly/var-tmpfs-mirror/ftp/usrflash/Project/PMAC Script Language/step-scan/trigger.plc
./var/ftp/usrflash/Project/PMAC Script Language/step-scan/trigger.plc

but maybe PowerPMAC could not interpret it.

I am trying to use submodules of git to version my codes as I have a lot of devices that could be updated at once if it works.

Is there a way to include custom folders and interpret them as native folders such as PLC Programs?

Note: just adding the file does not work for me because IDE creates a copy of my submodule and I lose the files tracking from git.

Thanks

George Kontogiorgos

January 11, 2021

Hi Eric!

Our robot is basically three granites, where two of them form a wedge and they are over the third granite. One motor control the wedge position and other motor compensate the movement, so we can perform X and Y movements purely by kinematics transformations.

We develop a plc to peform this safety but the complexity level increased too much and we decided to remove the individual motors from final users and the Curt Wilson answer's work very good.

November 23, 2020

You have a couple of possibilities. One is to do the calculations yourself in the kinematic subroutine -- e.g.:

if (KinPosAxisA > MyMaxA || KinPosAxisA < MyMinA) …

The other method is to assign an additional virtual motor that maps directly to the axis -- e.g.:

KinPosMotor11 = KinPosAxisA

Set your motor software limits for this virtual motor to the axis software limits you desire.

You will need to define this as an inverse kinematic motor in the same coordinate system -- e.g.:

&1 #11->I

You will also need to disable other faults on this virtual motor: hardware limits, amplifier fault, following error.

I prefer the second method but I couldn't find a way to interlock the individual motors looking to kinematics axes limits. If I move a individual motor by #4j=100 for example and motor 4 belongs to refered kinematics, the KinPosAxisA could reach a forbidden zone.

November 20, 2020

Hello

Is there a way to impose software limits to KinPosAxisA for example?

I would like to define my robot a limited work volume and the individual motors software limits does not work form me because I need the full range of some joints in order to perform the entire motion.

George

August 25, 2020

You might want to look at Motor[x].BrakeOffDelay and Motor[x].BrakeOnDelay elements.
They are designed to help mitigate this type of situation.

Hi Dave!

Thank you for reply and hope this message finds you well.

The Motor[x].BrakeOffDelay and Motor[x].BrakeOnDelay does not work for me because its behaviour is to delay the brake commnd after AmpEna=1. When I command j+ the motor begins producing force and brakes are enagaged yet.

Thats why I would like to delay the s-curve trajectory.

August 24, 2020

Hi!

My system uses air pads to levitate a very heavy granite and one stepper motor controls its movement with encoder feedback for closing loop. I am using brake output to control the pneumatic valves of this pneumatic system.

I would like to know if it is possible to implement a delay on trajectory, because my system takes some seconds to stabilize when AmpEna = 1. If we try to command some movement before the establishment of the air gap, the control will diverge since the granite is locked.

I saw that we have the trajectory pre-filter, but this structure allows delays in order of servo cycles times, I need more delay time, is it possible?

I would like to perform this on jog commands for individual motors and on motion programs.

Regards

George

July 24, 2020

Hi Steve,

Thank you for the document. I will try this work-around.

July 15, 2020

Hi all!

I would like to ask why EQU toggle when ServoCapt cross zero.

My suspect is that the compare registers are not dealing well with two's complement when the register becomes positive (example: 111111..... to 000000...)

When I use CompA and CompB on positive or negative domain strictly, it works as expected.

Maybe its related to Choi Woo Shik question (http://forums.deltatau.com/showthread.php?tid=3089)

Firmware: 2.5.4.0

IDE version: 4.3.2.19

Thanks!

George

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