Shop OBEX P1 Docs P2 Docs Learn Events
PSC loses power — Parallax Forums

PSC loses power

thomasloventhomasloven Posts: 2
edited 2006-04-27 20:23 in General Discussion
Hi.
I'm using a Parallax Servo Controller (PSC) hooked up to a computer via the serial port to controll a number of servos.

After finally getting my cmos->ttl level converter to work, I could run my servos whitout problems.
A day or two later, however, as I started up the PSC, they wouldn't move a bit.

When I first plug everything in and start the PSC, I can feel resistance as I try to manually turn the servos, so the controller is defending the position well.
But as soon as I try to send a command to the controller, the resistance is lost. All the servos just die...
The problems appear regardless of which channel I try to change. Even those with no servo plugged in.
Nothing has been changed in neither the setup nor the code, and the green led flash as I send commands to the PSC.

I've been thinking this is probably a problem with the power to the servos, but replacing the battery makes no difference.

Any ideas on what this could be would be highly appreciated.

Thanks in advance

//Thomas

Edit: I'm aware this doesnt realy belong in the Basic Stamp forum... but looking at the description and refering to other posts about simmilar matters, this seemed the best choice...

Post Edited (thomasloven) : 4/26/2006 9:11:21 PM GMT

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-27 00:01
    This thread is being moved from the BASIC Stamp Forum to the Sandbox Forum.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • bulkheadbulkhead Posts: 405
    edited 2006-04-27 03:07
    I get a problem similar to this. I have my javelin stamp sending the commands to the PSC. I first boot up the javelin, allow it to send the first servo positions to the PSC, then I power on my servos. This way, my servos don't go to the middle position then ramp to their starting positions.

    Sometimes, when I switch on the servo power switch, nothing happens. The servos don't even move at all. I usually correct this by shutting down everything and trying again. For an unknown reason, retrying several times always gets it to work again. I'm thinking this may just be a bug? It seems like the power switch doesn't lead directly to the servos, but goes through a main power control transistor or something.

    Another thing. I couldn't get my PSC to work with my javelin until I ran them off of separate batteries. I tried all sorts of batteries, running only 1 servo (for almost no load) and it wouldn't work. The PSC is strange, and a lot of its behavior seems unexplainable...
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-27 14:48
    The Servo Power Switch on the PSC directly connects incoming power to the servos.· There is no control circuit or power transistor in between.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • John BJohn B Posts: 82
    edited 2006-04-27 15:35
    Thomas,
    Are you able to communicate with the PSC? Specifiically, can you send a request for the version number and receive it? It sounds like there is a problem with the hardware.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    John Barrowman
    Engineering
    Parallax, Inc.
  • thomasloventhomasloven Posts: 2
    edited 2006-04-27 20:23
    Well... this is kind of embarasing...

    It was a hardware problem... the ground and the signal was shorted out...

    Thanks for the quick replies though, and sorry for posting in the wrong forum.

    //Thomas
Sign In or Register to comment.