OCCRA
Go to Post Engineering fundamentally comes down to problem solving, and if the students can't get excited and inspired by the problem solving process because someone has spoon fed them a solution, then nobody wins. Give a man a fish, he'll eat for a day. Teach a man to fish, he'll eat for a lifetime. - kevinw [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Events   CD-Media   CD-Spy   FRC-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 08-04-2007, 11:07 PM
GMAdan's Avatar
GMAdan GMAdan is offline
Team member turned mentor
AKA: Daniel A. Cobar
FRC #1881 (GAMMA Elite)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2006
Location: Paterson, NJ
Posts: 110
GMAdan has a spectacular aura aboutGMAdan has a spectacular aura about
Send a message via AIM to GMAdan
Consolidating PWM's to one serial cable

Sorry if this question has been answered in a previous thread, but i have searched and i can't find my answer.

I heard and from what I read on ifi robotics' website one wire of the three wires on the (the red one) is not used because it provides power which is not needed in the system we use. So if this is true could I in the interest to keep the number of pins needed to a minimum just not connect the red wire? So in turn I would only need two wires per victor for the signal.
  #2   Spotlight this post!  
Unread 08-05-2007, 07:29 PM
bear24rw's Avatar
bear24rw bear24rw is offline
Team 11 Programming Captain
AKA: Max T
FRC #0011 (MORT)
Team Role: Programmer
 
Join Date: Sep 2005
Rookie Year: 2005
Location: Flanders, NJ
Posts: 385
bear24rw is a splendid one to beholdbear24rw is a splendid one to beholdbear24rw is a splendid one to beholdbear24rw is a splendid one to beholdbear24rw is a splendid one to beholdbear24rw is a splendid one to beholdbear24rw is a splendid one to behold
Send a message via AIM to bear24rw
Re: Consolidating PWM's to one serial cable

Where did you see this information, i'v never heard that you only need sig and gnd.. but i agree it could be nicer to just have to run two wires
  #3   Spotlight this post!  
Unread 08-05-2007, 09:19 PM
GMAdan's Avatar
GMAdan GMAdan is offline
Team member turned mentor
AKA: Daniel A. Cobar
FRC #1881 (GAMMA Elite)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2006
Location: Paterson, NJ
Posts: 110
GMAdan has a spectacular aura aboutGMAdan has a spectacular aura about
Send a message via AIM to GMAdan
Re: Consolidating PWM's to one serial cable

from Ifi robotics
General Notes:

1. The red wire (center pin) on the PWM cable connected to the Victor is an open circuit. There is no reason to disconnect this wire in the cable. The Victor does not source or draw power on this line.
  #4   Spotlight this post!  
Unread 08-05-2007, 09:20 PM
ZZII 527's Avatar
ZZII 527 ZZII 527 is offline
"Scale Electric Vehicle"
AKA: Shane Colton
FRC #0097
Team Role: College Student
 
Join Date: Feb 2004
Rookie Year: 2003
Location: Cambridge, MA
Posts: 366
ZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond reputeZZII 527 has a reputation beyond repute
Send a message via AIM to ZZII 527
Re: Consolidating PWM's to one serial cable

As far as I know this is true. Somewhere in the Victor documentation it says that it neither sinks nor sources current on the 5V line and does not need to be connected. I don't know if it violates any rules to just use two wires.

Edit: I guess it says it does not need to be disconnected. So not explicitly stated in the documentation, but still true that you technically don't need it.

Also makes me wonder if the signal and power ground are internally connected or isolated (I suspect the latter). Bad practice not to use a separate signal ground line, anyway, I would think.
__________________
MIT Mechanical Engineering
>> College Mentor, Team 97: Cambridge Rindge and Latin School with The Edgerton Center, MIT Mechanical Engineering, Bluefin Robotics, and Draper Laboratory
>> Alumnus, Team 527: Plainedge HS

Last edited by ZZII 527 : 08-05-2007 at 09:23 PM.
  #5   Spotlight this post!  
Unread 08-06-2007, 07:08 AM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,033
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Consolidating PWM's to one serial cable

The Victor does not use the power pin as the Victor derives it's power from the separate power input(s). Servos, however, still need the power input from that third pin. Don't forget that the center pin is tied to the 7.2 volt back up battery when the backup is connected.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
All is better now, NOS parts are working fine. Why does this year's game remind me of Violet in Willie Wonka? Hmmmm, I see blueberries!
  #6   Spotlight this post!  
Unread 08-06-2007, 11:46 AM
GMAdan's Avatar
GMAdan GMAdan is offline
Team member turned mentor
AKA: Daniel A. Cobar
FRC #1881 (GAMMA Elite)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2006
Location: Paterson, NJ
Posts: 110
GMAdan has a spectacular aura aboutGMAdan has a spectacular aura about
Send a message via AIM to GMAdan
Re: Consolidating PWM's to one serial cable

Thank you all for your replies. Just to make sure, this means I can exclude the red wire in my serial connections. I just to have to make sure to include them for the servos.
  #7   Spotlight this post!  
Unread 08-06-2007, 12:13 PM
Qbranch's Avatar
Qbranch Qbranch is offline
wow college goes fast.
AKA: Alex Suchko
FRC #1024 (Kil-A-Bytes)
Team Role: Alumni
 
Join Date: Apr 2006
Rookie Year: 2006
Location: Indianapolis
Posts: 1,174
Qbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond repute
Re: Consolidating PWM's to one serial cable

I would suggest that you still put your ground wire for the PWM signal in your DB9 cable.... using common point grounding for signals like that when you have noisy compressors and motors usually introduces their noise into your small 5VDC signals that can cause wierd and hard to troubleshoot control problems.

Still, this would get you 8PWM sigals and one ground per cable for the Victor drives. Very interesting....

Did you also consider using CAT5 (Ethernet) cable? The RJ series connectors are quicker to disconnect/connect and are just as secure as the DB9 cables... but its pretty much a draw for which is better.

It'll be interesting to see how this turns out....

-q
__________________



2008 Championship Rockwell Automation Innovation in Control Award Winners
Electrical Engineer Illini
1024 | Programmer '06, '07, '08 | Driver '08
  #8   Spotlight this post!  
Unread 08-06-2007, 12:26 PM
GMAdan's Avatar
GMAdan GMAdan is offline
Team member turned mentor
AKA: Daniel A. Cobar
FRC #1881 (GAMMA Elite)
Team Role: Mentor
 
Join Date: Dec 2006
Rookie Year: 2006
Location: Paterson, NJ
Posts: 110
GMAdan has a spectacular aura aboutGMAdan has a spectacular aura about
Send a message via AIM to GMAdan
Re: Consolidating PWM's to one serial cable

Quote:
Originally Posted by Qbranch View Post
I would suggest that you still put your ground wire for the PWM signal in your DB9 cable.... using common point grounding for signals like that when you have noisy compressors and motors usually introduces their noise into your small 5VDC signals that can cause wierd and hard to troubleshoot control problems.

Still, this would get you 8PWM sigals and one ground per cable for the Victor drives. Very interesting....

Did you also consider using CAT5 (Ethernet) cable? The RJ series connectors are quicker to disconnect/connect and are just as secure as the DB9 cables... but its pretty much a draw for which is better.

It'll be interesting to see how this turns out....

-q
The CAT5 does sound like an interesting solution. Only problem i see with that is that the CAT5 wire to my memory ( i could be wrong) only has 8 pins. So that would make for a weird distribution of wiring.
Unless I put 4 victors per CAT5 wire (if i remove the ground) and then have a CAT5 wire just for grounding purposes, which may workout that I can still give each victor its own ground.
Thank you for the idea. Sorry i was kinda thinking out loud there.
  #9   Spotlight this post!  
Unread 08-06-2007, 12:51 PM
Qbranch's Avatar
Qbranch Qbranch is offline
wow college goes fast.
AKA: Alex Suchko
FRC #1024 (Kil-A-Bytes)
Team Role: Alumni
 
Join Date: Apr 2006
Rookie Year: 2006
Location: Indianapolis
Posts: 1,174
Qbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond reputeQbranch has a reputation beyond repute
Re: Consolidating PWM's to one serial cable

Quote:
Originally Posted by GMAdan View Post
The CAT5 does sound like an interesting solution. Only problem i see with that is that the CAT5 wire to my memory ( i could be wrong) only has 8 pins. So that would make for a weird distribution of wiring.
Unless I put 4 victors per CAT5 wire (if i remove the ground) and then have a CAT5 wire just for grounding purposes, which may workout that I can still give each victor its own ground.
Thank you for the idea. Sorry i was kinda thinking out loud there.
No, your absolutely right. The CAT5 does have just that many connectors and would definitely make for wierd distribution... also CAT5 normally is single core and because of that it doesnt have a long mechanical life when it comes to bending/vibration, and running a seperate wire for grounding does introduce, again, the possibility for wiring in more noise (every wire is afterall an antenna weather we want it to be or not ).

So, if I were you, I'd stick with the DB9. Its a great solution..... think you might see some nifty connection boxes on 1024's robot next year...

-q
__________________



2008 Championship Rockwell Automation Innovation in Control Award Winners
Electrical Engineer Illini
1024 | Programmer '06, '07, '08 | Driver '08
  #10   Spotlight this post!  
Unread 08-06-2007, 01:40 PM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 10,033
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Consolidating PWM's to one serial cable

Quote:
Originally Posted by Qbranch View Post
also CAT5 normally is single core and because of that it doesnt have a long mechanical life when it comes to bending/vibration, and running a seperate wire for grounding does introduce, again, the possibility for wiring in more noise (every wire is afterall an antenna weather we want it to be or not ).
The correct term is solid wire and you are correct, solid is not a good choice for moving objects as it is prone to fail with repeated vibration. The problem with a single ground is not so much as an antenna as that the noise for each of the signals is added in the common return wire (ground...although not really ground). This is sometimes referred to as "ground loop". In the case of multiple Victors, motor noise will be added as well since there is not a perfect return for motor current to the battery for each branch circuit. Some motor current is bound to flow on the common PWM wire.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
All is better now, NOS parts are working fine. Why does this year's game remind me of Violet in Willie Wonka? Hmmmm, I see blueberries!
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
home-made pwm's? darkorbit Electrical 2 02-17-2007 07:06 PM
usb to serial cable karinka13 Technical Discussion 4 02-10-2006 04:30 PM
USB-Serial Cable + Terminal Spencer E. Programming 3 01-22-2006 11:16 AM
Bluetooth serial cable replacement seanwitte Technical Discussion 2 02-13-2004 04:25 PM
Serial Cable Andrew Rudolph Technical Discussion 9 08-15-2002 09:09 PM


All times are GMT -5. The time now is 05:45 PM.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi