Custom PWM Cables and R69

[FreakyAntelope]

We are planning on making our own PWM cables this year, rather than buying the expensive ones from IFI, as I know teams have in the past. R69, however, states that "... Every speed controller and relay module must be connected via PWM cable to the Robot Controller...".

I assume that this rule is about the signals, and not the actual cables, but I wanted to check to make sure everyone else was reading it the same way I was. "PWM cable" does not need to be the exact cable purchased from IFI, so long as it is the correct AWG (by R90), and has the correct crimp connectors on the ends, correct?

By the way, if you are looking into making PWM cables yourself, I found that newark.com had much lower prices than digikey on the pins and housings, although they did not sell the molex crimper.

Thanks,

Toby

[jgannon]

Originally Posted by FreakyAntelope

We are planning on making our own PWM cables this year, rather than buying the expensive ones from IFI, as I know teams have in the past. R69, however, states that "... Every speed controller and relay module must be connected via PWM cable to the Robot Controller...".

I assume that this rule is about the signals, and not the actual cables, but I wanted to check to make sure everyone else was reading it the same way I was. "PWM cable" does not need to be the exact cable purchased from IFI, so long as it is the correct AWG (by R90), and has the correct crimp connectors on the ends, correct?

By the way, if you are looking into making PWM cables yourself, I found that newark.com had much lower prices than digikey on the pins and housings, although they did not sell the molex crimper.

Thanks,

Toby

PWM is a reference to the pulse-width modulated signal, and does not refer to any particular brand of cable. So long as your wire gauge is at least as big as the IFI cables, you should be fine.

[Al Skierkiewicz]

Originally Posted by FreakyAntelope

We are planning on making our own PWM cables this year, rather than buying the expensive ones from IFI, as I know teams have in the past. R69, however, states that "... Every speed controller and relay module must be connected via PWM cable to the Robot Controller...".

I assume that this rule is about the signals, and not the actual cables, but I wanted to check to make sure everyone else was reading it the same way I was. "PWM cable" does not need to be the exact cable purchased from IFI, so long as it is the correct AWG (by R90), and has the correct crimp connectors on the ends, correct?

By the way, if you are looking into making PWM cables yourself, I found that newark.com had much lower prices than digikey on the pins and housings, although they did not sell the molex crimper.

Thanks,

Toby

Toby,
The PWM cables are available in any length, from almost any hobby shop in the country. Many teams make their own by buying 3 conductor ribbon cable and the appropriate housings. Newark does sell these items and the crimper but (and this is a big one) the Newark minimum order is beyond most teams. I believe at last count is was $125 not including shipping. Even I have stopped buying from Newark (at work) for most parts due to the high minimum.

[fimmel]

there aren't any rules about cutting the cables and splicing them to make them shorter are there? im trying to make a very nice control board layout this year so its easy to explain to the newer members on our team.

/forest

[DonRotolo]

Try http://www.chiefdelphi.com/forums/sh...5&postcount=26, good source for pins and bodies.

For 24 ga or 22 ga 3-conductor wire (made by HiTec), search eBay for "Servo Wire", or any R/C hobby shop will have it or can get it in a few days. About $15 for 50 feet.

Radio Shack sells a crimper - 276-1595 - that crimps these pins perfectly. $11.

Don

[Al Skierkiewicz]

Originally Posted by fimmel

there aren't any rules about cutting the cables and splicing them to make them shorter are there? im trying to make a very nice control board layout this year so its easy to explain to the newer members on our team.

/forest

No,
There is no rule about splicing. However, why add another source of possible failure. If a PWM is too long, you can fold it back on itself and use a tiewrap to make it neat. If you have to move the device to which it is connected then you have to replace the cable anyway.

[Joe Johnson]

Originally Posted by Don Rotolo

Try http://www.chiefdelphi.com/forums/sh...5&postcount=26, good source for pins and bodies.

For 24 ga or 22 ga 3-conductor wire (made by HiTec), search eBay for "Servo Wire", or any R/C hobby shop will have it or can get it in a few days. About $15 for 50 feet.

Radio Shack sells a crimper - 276-1595 - that crimps these pins perfectly. $11.

Don

Here is another ChiefDelphi.com thread that has sources a for pins & housings and crimpers to make your own PWM cables.

Joe J.

[EricS-Team180]

Thanks Don and Joe! Our crimper and connectors seem to have "sprouted legs and walked away". I was just thinking about replacing them...

[kaszeta]

I've had good luck with the folks at Hansen Hobbies: http://www.hansenhobbies.com/products/connectors/

Custom-length PWM cables really clean up your robot's wiring. And if you need longer cables, this is the best solution (two PWM cables end-to-end is asking for trouble).

[Phalanx]

Originally Posted by kaszeta

I've had good luck with the folks at Hansen Hobbies: http://www.hansenhobbies.com/products/connectors/

Custom-length PWM cables really clean up your robot's wiring. And if you need longer cables, this is the best solution (two PWM cables end-to-end is asking for trouble).

We've used www.HansenHobbies.com ourselves about 3 or 4 times for such. Very reliable and quick to ship, except for one time when it took 3 weeks.

[dfukuba]

I have a different question regarding the PWM cables. There are three wires,

White-Signal
Black-Ground
red- +5V

In other robotic projects I'm able to wire my ESCs using only the White cable. Which is really the only thing that the RC needs to see. I was wondering if this is legal or not in first (to use only the white wire that is)

--Dan

[Al Skierkiewicz]

Daniel,
The speed controllers do not use the 5 volt wire but do use the signal wire and ground. I am having a brain cloud on the Spikes, but I believe all three wires are in use but the relay outputs are different than the PWM outputs on the RC. The servos use all three. I would prefer to use the standard PWM cable for all three and have standard wiring throughout the robot.

[JBotAlan]

Originally Posted by Al Skierkiewicz

I am having a brain cloud on the Spikes, but I believe all three wires are in use

You are correct. You've got ground, forward, and reverse. I honestly couldn't tell you which is forward and reverse, but I know all three are in use.

I don't think that it's a good idea to use 1-wire or 2-wire PWM cables because it's non-standard and I'm not sure if it would cause the parts to malfunction. It's not worth the risk; you don't gain that much weight from leaving the PWM cables alone.

JBot

[Phalanx]

Originally Posted by Al Skierkiewicz

Daniel,
The speed controllers do not use the 5 volt wire but do use the signal wire and ground. I am having a brain cloud on the Spikes, but I believe all three wires are in use but the relay outputs are different than the PWM outputs. The servos use all three. I would prefer to use the standard PWM cable for all three and have standard wiring throughout the robot.

The spikes use all 3 wires. The red and white wire are for the fwd and rev signals. The black is ground.

Unless the device needs +5volts of power, then only the ground and signal wires are needed.