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Thread: USB transmission times

  1. #1
    Join Date
    Jun 2016
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    9

    Default USB transmission times

    I have been doing some research as to why when my desktop rapid moves, sometimes it will act like it lost a firm grip on the axes and doesn't move as far as it thinks it does. Messes up the whole part when it happens. I don't think I have my rapid up too fast, I think its at 5ips. I found an interesting post on a thread that suggested to jog the machine, then go to "UD" and see what the Packet Transmission time was. On the screen it says anything faster than 20ms is "good". Well, mine averages about 80, sometimes hitting faster. My machine isn't particularly slow, and I am not running any other software when I did the test. What gives? How bad is 80ms? How do I fix the issue? What is the bottleneck? ANY help would be appreciated.

  2. #2
    Join Date
    Jun 2016
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    Okay just did some more testing. If i do a 4 inch move i get different times for x and y and when i move both at the same time.

    If i move at 2ips i get the following
    x = 70's
    y = 70's
    x&y = 140's

    With a move speed of 3ips
    x = 30's
    y = 50's
    x&y = 80s

    with a move speed of 4ips
    x = 20.6ms
    y = 20.5ms
    x&y = 66.4ms

    with a move speed of 5ips
    x = 20.8ms
    y = 20.6ms
    x&y = 35.4ms

    if i manually move at 6ips, it stalls out and doesnt move as far as it should. but with a program running at 6ips it does fine a good portion of the time.

  3. #3
    Join Date
    Mar 2013
    Location
    Memphis TN
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    696

    Default

    What are the specifications for your computer?
    What type of USB does it have?
    Are you running ANY other active software on that computer?
    Is it hooked to the internet?
    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

  4. #4
    Join Date
    May 2014
    Location
    MA
    Posts
    442

    Default

    Nick, you're reading that backwards... That's the time it takes for a signal to get to your controller, you want that as small of a number as possible. That screen is telling you that your transmission rate is significantly slower than what ShopBot recommends. You want it to be 20 or LESS.

    Mine's around 15 ms and I have my jog rate set at 22 IPS with no stalls or lost steps.

    2018-06-28 at 3.31 PM.jpg

  5. #5
    Join Date
    Apr 2013
    Location
    Kennebunkport, Maine
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    4,094

    Default

    Nick,
    Make sure it's a single axis move typed into the command line....like MX,4.
    Only time I've got #'s that high was a multi axis move, or a radio button move...usually around 16-18ms for both our Desktops.
    One issue I had in the beginning was I anally grouped/tied all my wires in the prettiest coils and wire runs....WRONG
    Got crosstalk and problems!
    Once wires were spread out and uncoiled...problems went away.
    DID find out back then that using the same USB port that was used when setting up was important, and checking different ports first made a difference(and then resetting SB3 while that port was used).
    There's a way to make sure that port has priority, but I forget
    DO make sure that the USB Suspend power saving feature is turned OFF.
    scott

    Oh..Move speed and Jog speed we eventually normally use wound up as Move 2IPS, and Jog 4IPS as a rule of thumb "normal"
    Scott Plaisted
    2013 Desktop/spindle/VCP 9
    Maine

  6. #6
    Join Date
    May 2014
    Location
    MA
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    442

    Default

    Be warned that testing against a single axis move might get you a faster (lower) number but also make sure you test real world scenarios. A high speed jog in 3 axes is something that's reasonably likely to happen. You don't want comms errors when that's happening so test against that.

  7. #7
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    Apr 2013
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    Kennebunkport, Maine
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    Eric,
    Pretty sure a specified single axis test like in the instructions, is so you're comparing apples to apples?
    scott
    Attached Images Attached Images
    Scott Plaisted
    2013 Desktop/spindle/VCP 9
    Maine

  8. #8
    Join Date
    May 2014
    Location
    MA
    Posts
    442

    Default

    You should test the way that you cut. If you cut only moving one axis at a time test that way, if you move multiple axes at a time during cutting, test that way.

  9. #9
    Join Date
    Apr 2003
    Location
    ShopBot Tools, Inc, Durham NC
    Posts
    187

    Default

    Hi Nick,

    Sorry for the speed issues. From the sounds of it, in your problem file the tool is stuttering and losing steps when it is doing those jogs, because the USB transmission is not keeping up with the needed flow (it is a streaming type of issue you sometimes see when watching a video).

    Of course, from the sounds of it, you and everyone else here has already figured that out. And, we're looking at the [UD] Diagnostic to get a little more info. As has been suggested here, the way to run that is with a simple move from the Command Line, an MX or MY, of say 4 inches. The diagnostic here only takes a single test sample during the move and that means there can be some variation in what you get. In theory, the USB transmission speed for this move will not have much relationship to the move speed, but it makes sense to use something reasonable, like 4ips, just to make sure things aren't getting hung up in an acceleration ramp. Do it a few times. Appreciate that there is a huge variation in the way the PC is prioritizing USB action ... so you will get a lot of variation. If you get many values over 20ms, then there probably is something that can/should be done to improve transmission efficiency.

    I don't know if you saw it, but there is a help document in the software on use of [UD] that you may want to look at.

    You mentioned being able to re-create the problem with "manual" moves but not with moves in a file. If by "manual" you mean with the Yellow KeyPay, then you should probably ignore that. What happens with the keypad is that smaller USB packets are being transmitted so that the KeyPad will be more responsive to a key lift and stop the tool quickly -- because you can't get back a packet that has been sent to the tool. So, if you are anywhere near having a transmission efficiency issue, that will show up trying to go fast with the KeyPad.

    The way to do a manual move to test is by trying various speeds with a Command line command. When you issue an MX from the command line, it is processed just like it is in a file.

    All that said, the Desktop is quite high resolution compared to our Gantry Tools and really does require good USB efficiency to get top speeds.

    So ... now do we get your number lower?

    The usual/typical culprits are:
    1) anti-virus software; best to not run anything other than the basic windows security system. This was called "Security Essentials" in Win7 and 8 and sometimes had to be installed separately. Now it's all there. Many add-in virus and malware systems insist on checking the USB flow ... which is not a good thing for us.
    2) USB 3.0; the drivers for USB 3.0 on some systems do not work well (mostly before windows 8.1). You can try to test on a USB 2.0 port (often a black tongue in the socket on the computer rather than a blue one); or try with or without a USB 2.0 hub (this one is a little bit of a mystery, sometimes helping, sometimes not). On my current win10 Dell laptop, which I have done nothing other than #1 to, I routinely see the speed around 12ms, in both USB 3.0 and USB 2.0 connections.
    3) USB is generally fast enough on any recent computer to get you up to speeds as fast as the motors can handle on that tool 8-10ips. So, if after puzzling with this a bit, you don't get your speed working a bit better, you should give our support guys a call -- they have a lot of experience fine-tuning this USB efficiency. And, while your waiting, set the Jog speed down nearer the move speed to get the files going.

    [I did not ask about the age of your tool. I'm assuming, new (in which case we would have tested it for top speeds before it left here)? But if an older tool, it may be that over time a bit of motion resistance has built up. Stepper motors are weaker the faster they go, so if the tool is slightly binding for some reason, faults will happen at high speeds, not slow speeds.]

    Our Support Team should be regularly checking emails over the weekend ... so you can always send them a tech support note if you're still having trouble (make sure you mention we've discussed this first level stuff).

    Ted Hall, ShopBot Tools

  10. #10
    Join Date
    Jun 2016
    Posts
    9

    Default

    All, thank you so much for all the replies! I set the move speed during a program down to 5 from 6 and my problem went away so I got on with life and the work I needed to finish. I thought to myself yesterday, I wonder if anyone ever responded to my post on the forum? Sure enough a lot of you offered help which is amazing. Lots of questions to answer, I will do my best!

    What are the specs of the computer you are running?
    I am using my old engineering computer. When I built my new PC 2 years ago I re-purposed the old one to be my garage PC. It has two USB 3.0 ports and two USB 2.0 ports.
    Motherboard - Gigabyte ga-x58a-ud3r
    Processor - Intel I7-950 (Quad core 3.06 GHz)
    Memory - 12 GB, 3x2GB DDR3 1600
    Hard Drive - Intel X25-M Sata II SSD
    Operating System - Windows 10 64bit
    Anti-virus - Malwarebytes Premium

    How old is your machine?
    I bought it used about 3 years ago, I think when I bought it, it was already 4-5 years old. Still in great shape I think. I keep it in my garage which has a dehumidifier set at 45% and the previous owner kept it in his air conditioned garage.

    Are you using USB 3.0?
    I tested it with the machine plugged into my USB 3.0 hub which is connected to my USB 3.0 port and the numbers were the same. The table shows the machine plugged directly into the USB 2.0 port on the motherboard though.

    Does it run faster with your antivirus software off?
    Yes. I run Malwarebytes on all my computers, and after spending 30 minutes on the phone with their tech support we figured out what was going on. With the software off I get about 6ms faster times on average. We figured out what specific setting to turn off on the software so I can have protection and the same speed as when the software is closed. For those of you that have Malwarebytes, disable "self protection" and ransomware protection.

    Did you use the yellow keypad to make the moves?
    Yes. I would highlight the number in that window, change it, then hit enter to make the moves exactly 4". I have now done the same test but with using the command line and the numbers are faster.


    I have attached two tables. The first table is with malwarebytes on, the second table is with it essentially off. What I notice is the numbers become less consistent with it off. Some numbers are very fast, but not all the time. I will say it doesnt seem to matter a whole lot what speed (ips) I am running as far as transmission time is concerned. I also don't see a lot of difference between single axis movement and two axis movement. Three axis movement oddly seems faster. I am still above the 20ms threshold, is there anything else I can do to speed things up?

    Move Speeds1.PNGMove Speeds2.jpg

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