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DynamoBen
09-28-2009, 10:48 PM
I picked up a serial PSC (Parallax Servo Controller) for $19. I intend on controlling some light up Skulls both pan and tilt for my show this year. Has anyone used the PSC plug-in for their show? How well does it work? Ultimately I'm trying to figure out if I need to build a DMX to PSC interface prior to Halloween.

Elmo2resc
09-28-2009, 11:04 PM
I did this last year and it worked great. You will have to build the following but I got all the parts from Radio Shack. Pretty simple after that with the right software. Let me know if you need any more help.

The following is from parallax's site.

http://forums.parallax.com/forums/default.aspx?f=21&m=180521

PC to PSC.bmp


RS-232 (PC) to Parallax, Inc. Servo Controller (PSC)



Our Parallax Servo Controller (#28023) is typically controlled by one of our microcontrollers. For PC control we have a USB version (#28823). For those who have the Serial version and wish to connect to the RS-232 Serial Port you can use the following schematic. It consists of only 5 discrete components which are readily available from Parallax, Inc., Radio Shack or any electronics store or distributor. With this schematic you have full control and can even use the PSCI software intended for the USB-PSC. Please note that a regulated 5V power supply is required for the circuit which also powers the PSC. This supply must be separate from the power supply for the servos, which connects to the screw terminals on the PSC. Take care.
NOTE: Any data sent to the PSC by the host will be echoed back through the RS-232 connection. This is a side-effect of using a single I/O pin for bi-directional serial communication. Be sure your host application disregards anything sent to the PSC. Essentially you will need to filter what you send from the receive buffer.


Component Description Source Part #
--------- --------------- --------- ------------
R1, R2 1K, 1/4W, 5% Parallax, Inc. 150-01020
R3 10K, 1/4W, 5% Parallax, Inc. 150-01030
Q1 NPN, 2N3904, TO-92 Parallax, Inc. 500-00001
Q2 PNP, 2N3906, TO-92 Parallax, Inc. 500-00003











Chris Savage
Parallax Tech Support


Post Edited (Chris Savage (Parallax)) : 3/24/2007 8:01:37 PM GMT

Image Attachment :
http://forums.parallax.com/forums/thumb.aspx?a=12825&ImageID=5861
PC to PSC.bmp (http://forums.parallax.com/forums/attach.aspx?a=12825) 226KB (image/bmp) This image has been viewed 2685 time(s).

DynamoBen
09-28-2009, 11:09 PM
I have already built the circuit and done some testing. My biggest concern was that it, the plug-in, didn't appear to follow the serial protocol in the documentation. In the end that doesn't matter much as long as it works.

BTW at what distance were you able to control your servos from the PC?

Elmo2resc
09-28-2009, 11:24 PM
my serial line was about 15'. maybe a little less. I am further away this year. I will have to test out the system just in case I need to adjust.

DynamoBen
09-29-2009, 12:03 AM
my serial line was about 15'. maybe a little less.

RS232 or TTL? Are you talking about PC to Converter or Converter to PSC?

Elmo2resc
10-02-2009, 05:32 PM
Ok, I measured my cable. I used a Cat 5 Cable hooked up to the serial port. It is 27' long. I have it in the following order.

PC serial port
27' Cat 5 Cable
Converter
10" servo cable
PSC

The power I used was from a PC power supply for the servos and the board.

This worked with no issues. I was only running three servos off the board. I had not tried to run any more then that.

Jerome

DynamoBen
10-02-2009, 06:37 PM
PC serial port
27' Cat 5 Cable
Converter
10" servo cable
PSC


Hmmm that's interesting I would have expected the PC to Converter length to be less than 3-6' to stay within the recommended length for RS232.

Elmo2resc
10-02-2009, 07:00 PM
I can't speak why it worked. It did though. I had everything mounted in the skull. It is still setup the same it was used last year.