LEDs connected to Solenoid Breakout. It's illegal, but why?

[RyanN]

From the rules, it is illegal to connect anything but solenoids and the line sensors to the solenoid breakout. We have 3 LED strings, pulling about 300mA a piece. We would love to save some space and connect them to the solenoid breakout board, but guess what...

<R60> Solenoid Breakout outputs shall be connected to pneumatic valve solenoids or photoelectric sensors, PN 42EF-D1MNAK-A2, only. No other devices shall be connected to these outputs.

Any reason why custom circuits are not allowed? It's adding unnecessary complication to our already over complicated robot.

[DonRotolo]

The only reason that matters is because it is in the rules. Same reason we're not allowed to use Duct Tape on the minibot.

I can speculate that they are concerned that teams will draw too much current from the breakout and make their pneumatics uncontrollable or erratic.

Side note: a 300 mA LED is about 1 watt. This will be BLINDINGLY bright.

[RyanN]

Originally Posted by DonRotolo

The only reason that matters is because it is in the rules. Same reason we're not allowed to use Duct Tape on the minibot.

I can speculate that they are concerned that teams will draw too much current from the breakout and make their pneumatics uncontrollable or erratic.

Side note: a 300 mA LED is about 1 watt. This will be BLINDINGLY bright.

Yep, they're pretty bright all put together. I think there are about 30 LEDs in the string.

[Alan Anderson]

Originally Posted by DonRotolo

I can speculate that they are concerned that teams will draw too much current from the breakout and make their pneumatics uncontrollable or erratic.

The NI 9472 Digital Sourcing Module has protection against extreme overcurrent, so you probably wouln't be able to cause any fires, but the documentation warns that at currents between 1 and 13 amps the module "may be damaged".

[Mr. Lim]

Originally Posted by RyanN

From the rules, it is illegal to connect anything but solenoids and the line sensors to the solenoid breakout. We have 3 LED strings, pulling about 300mA a piece. We would love to save some space and connect them to the solenoid breakout board, but guess what...



Any reason why custom circuits are not allowed? It's adding unnecessary complication to our already over complicated robot.

Believe me, my students were a bit ticked at this as well.

The solenoid breakout is simply the BEST way to power your LED light indicators.

Unfortunately, from my reading of the rules, that would be illegal.

I agree that we would all benefit from a loosening of the rules of what can be hooked up to the solenoid breakout to include custom circuits < 500mA.

[EricVanWyk]

I believe the best way to handle this is to make the request in the Q&A.

The wording for the rule change that would allow this would be awkward, as the solenoid breakout can sometimes be used with the 24V rail. I would hope that the rule change would not allow using that rail for LEDs.

[Bendito]

Does this rule apply to the 2012 season, as I can't find anything that specifically prohibits the LEDs in this year's manual?

<R60> Solenoid Breakout outputs shall be connected to pneumatic valve solenoids or photoelectric sensors, PN 42EF-D1MNAK-A2, only. No other devices shall be connected to these outputs.

[MrForbes]

I think the applicable rule this year is:

[R63]

Outputs from each Solenoid Breakout shall not cumulatively exceed 16W for the cRIO-FRC (8-slot) and 21W for the cRIO-FRC II (4-slot).

[Al Skierkiewicz]

There are other ways to control LEDs that do not include the solenoid breakout. 300 ma is (As Alan has pointed out) excessive for the solenoid module. The manufacturer recommends 75 ma per output as a safe use of this module. It is for this reason that electric solenoid actuators or 10 watts or less can be driven from this module as well.

[Joe Ross]

Originally Posted by Al Skierkiewicz

There are other ways to control LEDs that do not include the solenoid breakout. 300 ma is (As Alan has pointed out) excessive for the solenoid module. The manufacturer recommends 75 ma per output as a safe use of this module. It is for this reason that electric solenoid actuators or 10 watts or less can be driven from this module as well.

I'm curious why you think a 300 ma led is excessive but an 800 ma solenoid is ok.

[RufflesRidge]

Originally Posted by Al Skierkiewicz

The manufacturer recommends 75 ma per output as a safe use of this module.

The datasheet for the Solenoid Breakout board specifies 750mA per output channel.

[Al Skierkiewicz]

Sorry,
Left off the last zero. 750 ma at 12 volts is 9 watts.
Joe, I was considering the total for LEDs for three strings plus the loads likely for other devices as totaling more than one amp. As Alan reminded me last year the manufacturer has this rather odd table listing for trip modes. One of those lines for total current is this...
"1 to 6 A, Channel does not trip, Module may be damaged."

[Kevin Sevcik]

A Spike may be bulkier, but you could use one spike to switch two banks of LEDs by wiring each motor output to the positive side of the LED and running the common directly back to the PDB.

[billbo911]

Originally Posted by Kevin Sevcik

A Spike may be bulkier, but you could use one spike to switch two banks of LEDs by wiring each motor output to the positive side of the LED and running the common directly back to the PDB.

Alternatively, a simple transistor LED driver can be made. Use one digital out pin per LED string.
The driver only needs one CORRECTLY SIZED resistor and transistor per string to work. Just use +12vdc to power it, and control it via the DSC.

[Aren_Hill]

Originally Posted by Al Skierkiewicz

Sorry,
Left off the last zero. 750 ma at 12 volts is 9 watts.
Joe, I was considering the total for LEDs for three strings plus the loads likely for other devices as totaling more than one amp. As Alan reminded me last year the manufacturer has this rather odd table listing for trip modes. One of those lines for total current is this...
"1 to 6 A, Channel does not trip, Module may be damaged."

So if i had an LED strip rated at 200ma (12v) It'd be alright to run off the solenoid breakout?

If its only one strip and minimal other things using the breakout