RoboticsConnection User Forum / Serializer Robot Controller Support / RoboticsConnection Hardware Support / Intermittent timeouts and nacks when using servo command / Latest Posts

RE: Intermittent timeouts and nacks when using servo command

R4dsi — Wed, 07 Mar 2012 08:33:08 GMT

When I look at the disassembled code for CommunicationTask.ProcessJob in the latest version of RoboticsConnection.Serializer.dll, I noticed that the code ignores NACK and timeout exceptions up to 3 times, thus I suspect these get masked in many situations for users of that library at least.

RE: Intermittent timeouts and nacks when using servo command

R4dsi — Fri, 06 Jan 2012 20:01:47 GMT

[quote][b]EricZ (8/21/2010)[/b][hr]

What made me wonder about the setio command sending NACKs or timing out sometimes was this: When I look at the disassembled code for CommunicationTask[url=http://www.r4i-r4.de]r4[/url].ProcessJob in the latest version of RoboticsConnection.Serializer.dll, I noticed that the code ignores NACK and timeout exceptions up to 3 times, thus I suspect these get masked in many situations for users of that library at least. See below.
[/quote]It's a little tricky to get the firmware ID at this point since my code doesn't have that built into it.

RE: Intermittent timeouts and nacks when using servo command

EricZ — Sun, 27 Feb 2011 01:09:45 GMT

Last post I've seen on this was in september when you said you guys were still looking into this. I'm still having the issue, do you have any news or an ETA on a potential firmware upgrade?

Thanks for any update!

RE: Intermittent timeouts and nacks when using servo command

Don Lewis — Tue, 23 Nov 2010 22:42:23 GMT

I too have been experiencing some problems when panning a servo.
If I disable the tilt servo I get smooth pan action full range. If I enable
but not use the tilt servo I get some erratic pan behaviour in parts of the
range. Very predictable. That part of erratic is that while panning
the tilt will go up and down a bit without being sent a signal.
I have the previous generation Serializer with latest fw.
This problem has always been present.

Thanks,

RE: Intermittent timeouts and nacks when using servo command

EricZ — Tue, 23 Nov 2010 09:40:50 GMT

Jason, any news?

RE: Intermittent timeouts and nacks when using servo command

EricZ — Sat, 13 Nov 2010 12:08:12 GMT

Sorry for the big delay in responding jason, I've had a whole bunch of work stuff going on and haven't been able to get back to the robot for a while. It's a little tricky to get the firmware ID at this point since my code doesn't have that built into it. Since you repro'd the problem, do you still need this? I can get it if you do.

Also: is there a fix available yet?

RE: Intermittent timeouts and nacks when using servo command

jsummerour — Thu, 02 Sep 2010 22:12:48 GMT

Eric,

We're still looking into this...The serializer seems to be getting corrupt commands, and we're trying to figure out if it's simply dropped characters, noise, or something else.

I'll post more results, and hopefully a fix this weekend. :)

Best Regards!

RE: Intermittent timeouts and nacks when using servo command

jsummerour — Fri, 27 Aug 2010 21:46:47 GMT

Eric,

What firmware versions are you using? Thanks!

RE: Intermittent timeouts and nacks when using servo command

jsummerour — Fri, 27 Aug 2010 21:44:27 GMT

Hi Eric,

I have verified that we see this behavior too. The .NET lib was masking the error. It seems to occur most often when servo commands are sent VERY frequently...I'll keep you posted on the fix. :)

Best Regards,

RE: Intermittent timeouts and nacks when using servo command

jsummerour — Sun, 22 Aug 2010 20:22:00 GMT

Hi Eric,

Yes, I will be glad to look into this. I'm leaving for vacation Monday morning, and will be gone all week. But I will look into this as soon as I get back.

Yep, those NACKs would get filtered by the current .NET library wouldn't they...Thanks for the detailed debugging info...It always helps a ton! :)

I'll also get Ringo to start looking into it as well.

Best Regards,

RE: Intermittent timeouts and nacks when using servo command

EricZ — Sat, 21 Aug 2010 18:03:15 GMT

Oops, it looks like the code got munged when I posted it. Here's another try at it:

[quote]private void ProcessJob(CommJobInfo jobInfo)
{
    string s = jobInfo.Job.GenerateCommand();
    string response = "";
    uint num = 1;
    while (num <= 3)
    {
        try
        {
            this.SerialPortWriteLine(s);
            response = this.SerialPortReadLine();
            if (response != "NACK")
            {
                break;
            }
        }
        catch (TimeoutException)
        {
        }
        num++;
    }
    if (num < 3)
    {
        jobInfo.Job.ProcessResponse(response);
    }
}

[/quote]

RE: Intermittent timeouts and nacks when using servo command

EricZ — Sat, 21 Aug 2010 18:00:47 GMT

I've been looking for race conditions or other issues that might be misformatting the command, and I'll continue, but I don't that is the issue. BTW I've seen this behavior on your old version of the board and the new one.

What made me wonder about the setio command sending NACKs or timing out sometimes was this: When I look at the disassembled code for CommunicationTask.ProcessJob in the latest version of RoboticsConnection.Serializer.dll, I noticed that the code ignores NACK and timeout exceptions up to 3 times, thus I suspect these get masked in many situations for users of that library at least. See below.

Any way you can check the firmware to see in what situations a NACK can come back from the setio command (outside of a malformed command string) or what could cause it to time out?

[CODE REMOVED -- POSTED BELOW]

RE: Intermittent timeouts and nacks when using servo command

jsummerour — Fri, 20 Aug 2010 13:56:11 GMT

Hi Eric,

Our Serializer .NET lib is sending the same commands down, and I don't recall it getting any NACKs. Double check the command strings you're sending down to make sure you're not sending an additional invisible character down, which would throw the parsing off.

Can you type the commands in from PuTTY, and see the same behavior? If not, it is almost certainly your code that's speaking the protocol.

Best Regards!

Intermittent timeouts and nacks when using servo command

EricZ — Fri, 20 Aug 2010 02:18:10 GMT

When using the servo command to position a servo, roughly every 3rd or 4th time I send a command I'll time out waiting for the response, sometimes I'll then receive a NACK, and most of the time the 3rd time will work. I get the same issue with SetIO, but only every once in a while. 75% of the time things work fine.

Any suggestions? Can you tell me why setio would ever time out or nack? It seems like it is just sending a PWM signal to the servo, so I'm not sure why there' ever be much of a delay.

I've got the timeout set to 5 seconds and I'm doing direct serial port communication (not using any of your .net libraries, etc.)