cRIOs with patch cables

[ckerr]

I've been trying to figure out if it's permitted to detach the cards from the cRIO, place them elsewhere on the robot, and attach them back using a standard patch cable.

R64 (http://frc-manual.usfirst.org/viewItem/751) mentions allowing the attachment of cables to already existing ports, but if the patch cable were to count as a custom circuit then R71 (http://frc-manual.usfirst.org/viewItem/758) doesn't seem like it allows the attachment of custom circuits to the slots of the cRIO.

Does a patch cable alone between two non custom circuits count itself as a custom circuit? And if it doesn't, do the rules anywhere I haven't managed to find yet stop you from using a patch cable so that the cards of the cRIO aren't directly attached anymore?

[Jared]

What do you mean by cards? I'm assuming you mean the three cRIO modules which are NI 9201, 9402, and 9472 (kind of like this (https://www.google.com/search?q=9201&espv=210&es_sm=122&source=lnms&tbm=isch&sa=X&ei=1GbdUortAqHLsQTa94L4CA&ved=0CAwQ_AUoBA&biw=784&bih=771#facrc=_&imgrc=KTbozeswCokhQM%253A%3BlXufb6WLT1PhzM%3Bhttp% 253A%252F%252Fsine.ni.com%252Fimages%252Fproducts% 252Fus%252F041105_crio9201_l.jpg%3Bhttp%253A%252F% 252Fsine.ni.com%252Fpsp%252Fapp%252Fdoc%252Fp%252F id%252Fpsp-148%252Flang%252Fen%3B400%3B291)), and not the analog breakout/solenoid breakout that sit on top of the modules.

Regardless of if it's legal, you probably won't be able to do it. The connection between the cRIO and the modules is not a normal db-15 connector commonly used for serial ports. Even if you did find the right connector, there would be a lot of undesirable interference. The module was designed to be plugged straight into the cRIO with no extension cable. They made the connection as short as possible by mounting the socket directly to the cRIO's PCB to avoid interference.

[cgmv123]

It seems like the OP is talking about using a DB-25 cable (http://www.cablestogo.com/category/pc/pc-serial/db25-serial-cables) to separate the Analog and/or Solenoid Breakouts from the Analog/Solenoid Module (similar to how the DSC is separated from the Digital Module), which was legal last year per Q423, though last year is not this year, so I'd recommend asking Q&A again.

[Brandon Ha]

Regardless of legality, what are the benefits of removing the cards from the cRIO when there is a pre-made slot for them? There does not seem to be any space issues with the cRIO especially when u have the smaller 4slot ones.
I am just curious

[ckerr]

Thanks all for the quick replies, I think at this point we'll stay away from moving the modules, but we'll keep moving the breakout boards as a possible option in mind.

In regards to why we have space limitations, my team doesn't currently have access to the smaller four slot cRIOs at this time. Also with our current design, the limitation is regarding height as the cRIO with modules and breakout boards inserted is too tall and sticks up into where the ball is planned to go; which seems unwise since the ball could easily bump and heavily damage the breakout boards if they remain in their original positions.

[cglrcng]

Thanks all for the quick replies, I think at this point we'll stay away from moving the modules, but we'll keep moving the breakout boards as a possible option in mind.

In regards to why we have space limitations, my team doesn't currently have access to the smaller four slot cRIOs at this time. Also with our current design, the limitation is regarding height as the cRIO with modules and breakout boards inserted is too tall and sticks up into where the ball is planned to go; which seems unwise since the ball could easily bump and heavily damage the breakout boards if they remain in their original positions.

You might try one of these....A 3D printable cRIO cover looks very protective.

http://www.chiefdelphi.com/forums/showthread.php?t=125265

And the CAD plans are avail. on thingiverse

[philso]

Thanks all for the quick replies, I think at this point we'll stay away from moving the modules, but we'll keep moving the breakout boards as a possible option in mind.

In regards to why we have space limitations, my team doesn't currently have access to the smaller four slot cRIOs at this time. Also with our current design, the limitation is regarding height as the cRIO with modules and breakout boards inserted is too tall and sticks up into where the ball is planned to go; which seems unwise since the ball could easily bump and heavily damage the breakout boards if they remain in their original positions.

Connecting the Analogue and Solenoid Breakout Board to their respective CRio modules with male-to-female DB-25 ribbon cables should not cause problems and would allow you to place them in a more convenient location.

A large part of the function of those two boards is to serve as an adapter from the DB-25 connector on the CRio module to the 3-pin PWM cables. No signal processing occurs on either of the breakout boards so it makes no difference whether the signal is traveling through the PWM cable or your DB-25 ribbon cable. Just make sure your ribbon cables are only as long as they need to be and do not run adjacent to any power wiring for any significant distance. These caveats also apply to the PWM cables. The current rating of the ribbon cables is greater than the maximum output current rating of the Solenoid Module. You are not likely to want to use a very long ribbon cable so the series resistance will not have a significant effect.

[Owen Makin]

Just make sure your ribbon cables are only as long as they need to be and do not run adjacent to any power wiring for any significant distance.

What would be considered a significant distance? And what problems would start to occur?

[Al Skierkiewicz]

C,
One of the biggest reasons to not remove the modules and use jumpers to feed them is design. I look at the modules and the function they are designed to perform and think that performance can only be degraded by remoting them on the robot. You can use ribbon cables extensions for all of the interfaces, the DIO and solenoids work very well for this. The analog interface is a little more difficult since it has a power supply on it.

[philso]

double post

[philso]

What would be considered a significant distance? And what problems would start to occur?

This comment mostly applies to the cables connected to the Analogue Breakout Board. With the type of components you have in your typical robot, I would not want to run signal cables adjacent to power wires for more than 6 inches.

The current flowing in one wire will induce a current in a wire adjacent to it. This effect is stronger if the lenght of the wires adjacent to each other is longer, the wires are closer to each other or the current is higher. The induced current becomes and error in the second circuit, commonly called "noise", and may cause erroneous operation. Wires crossing at an angle, say greater than 30 degrees or so, will experience much less coupling.


C,
One of the biggest reasons to not remove the modules and use jumpers to feed them is design. I look at the modules and the function they are designed to perform and think that performance can only be degraded by remoting them on the robot. You can use ribbon cables extensions for all of the interfaces, the DIO and solenoids work very well for this. The analog interface is a little more difficult since it has a power supply on it.

The Analogue Breakout Board has a buck converter to drop the input voltage from 6~12Vdc down to 5Vdc to bias or power any external circuits such as potentiometers. Since Analogue Input Module has a resolution of 12-bits and its input currents are very low (input impedance of 1Mohm), the one or two feet of wire between the ground reference of the power supply and the ground reference of the Analogue Input Module will not cause a measurable effect.