Digital Sidecar relay ports: correct voltage?
 

Can anyone please tell me what is the correct voltage reading on the red&white wires coming out of the relay ports on the digital sidecar?

We are measuring 4.2 volts in the active state.

We have a Spike relay connected to a relay port, and the Spike is not working.

By "not working", I mean the Spike LED remains orange and there is no voltage across the Spike's output. We thought maybe the sidecar got damaged and is not outputting the right voltage.

There is 12 volts across the Spike input, correct polarity.

The battery is sufficient; it runs the motors that drive the wheels.

We swapped out the Spike and the new one doesn't work either.

We understand the following chart and tested all four states

red=0 white=0 brake (both outputs grounded)
red=1 white=0 reverse (reverse output polarity)
red=0 white=1 forward (normal output polarity)
red=1 white=1 brake (both outputs +12)

Unless there's something I'm missing, the only hypothesis that seems to fit the facts is that the signal voltage is not correct.


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Re: Digital Sidecar relay ports: correct voltage?
 

Do you see the Relay status lights (red/green/off) changing states while the Spike status light remains orange?

Normally, with those symptoms I'd say the Spike is not receiving a signal.

P.S. I checked my notes and I noted a 4.6v reading from a Relay output.

P.P.S. I checked the Spike documentation and it requires 3v minimum for the control signal.

Re: Digital Sidecar relay ports: correct voltage?
 

Hi Mark,

We saw the LED at the relay port on the sidecar change from green to off while the Spike relay remained orange.

We used a voltmeter to measure the voltage on the 3-wire cable (black/red/white) at the connector that plugs into the Spike. It measured about 4.2 volts (on the red and/or white wires) when active. So the Spike is getting a "signal"... I just don't know if it is the "correct" signal; I couldn't find a spec on what voltage the sidecar is supposed to output, nor could I find anything on the Spike datasheet about what input signal voltage level was required.



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Re: Digital Sidecar relay ports: correct voltage?
 

It's on page 3 of the Spike document - Control signal: 3v minimum.

I'd consider this a problem with plugging the PWM cable into the recessed Spike connection. It can easily go into the slot, but miss the internal connector entirely even after repeated tries.

If you're reading a signal at the Spike end of the PWM then the cable and connection at the DSC sound fine.

Re: Digital Sidecar relay ports: correct voltage?
 

Thanks Mark. Could you post a link to this document? The doc I have does not have this info.


Aha. That sounds more likely. I vaguely recall hearing something about this. We will look into it when we get the robot back.

We couldn't get it fixed in time, so we used the 24V solenoid break-out. All we needed was about 70ma. I asked a couple of students to find the specs for the output current capability of the 24V solenoid breakout, and they spent about and hour and a half looking but couldn't find it. You don't happen to have a link to a doc for that by any chance do you?


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Re: Digital Sidecar relay ports: correct voltage?
 

cRIO sourcing module
http://sine.ni.com/nips/cds/view/p/lang/en/nid/14175

control system docs (including the official power and data diagrams and a link to the datasheets for the Digital Sidecar, PD and Breakouts)
http://www.usfirst.org/roboticsprogr....aspx?id=10934

Re: Digital Sidecar relay ports: correct voltage?
 

Thanks Russ. Right under our noses. How embarrassing. I think after we've all recovered from the last 48 hours we'll have a little team meeting about where to find this kind of stuff.


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Re: Digital Sidecar relay ports: correct voltage?
 

If it's for a solenoid that's a perfectly fine solution.

If it's for anything else you will have to track down the issue with the Spike. <R65> restricts the Solenoid Breakout to solenoids only.

Re: Digital Sidecar relay ports: correct voltage?
 

I should say "thank you", but I think you've just ruined my whole day.

I think I'll wait a couple days before telling the team. They were so happy.

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Re: Digital Sidecar relay ports: correct voltage?
 

For Spike technical info. the place to go is the manufacturer at VexPro and the Spike Relay specific page.

Re: Digital Sidecar relay ports: correct voltage?
 

FYI... Don't forget there is a known LabVIEW VI problem associated with the RELAY control.

It's reported here http://decibel.ni.com/content/thread/6131?tstart=30 (and I only found it by accident).

If you are setting the relay to run in "Both Directions" it apparently works, but if you were like me and just wanted to turn something on, it was just dead.

Solution... open up the "RelaySet.vi" and connect the two "Relay Direction" terminals as shown in the NI post.

Phil.

Note: I really think a bigger deal should have been made about this. Is there a "known bugs" list anywhere...

I just "assumed" that the relay control would work..... It makes me start wondering about any code that should work, but doesn't..... coding error or known VI bug...

Re: Digital Sidecar relay ports: correct voltage?
 

Is this correction necessary? Our compressor seems to be working fine. However, an electromagnet on a Spike seems to have a little delay in releasing. Could this issue contribute to that? We originally attributed the delay to residual magnetism and added code to briefly reverse the magnetic polarity, but haven't had a chance to test it out yet.

Re: Digital Sidecar relay ports: correct voltage?
 

If you are using the Compressor VI, then it's not required, however if you are using the Relay control direcly then it may be required, depending what mode you are using it in (forward, reverse or both).

However, if your relay is working at all, then it's probebly not required... it's a show stopper.

BTW.... Electromagnet..... ???? is this part of some active actuator?
Wouldn't this be dissalowed by <R53>.

One assumes that when you turn on/off your electromagnet, something on your robot moves... Isn't that the definition of an "electric solenoid"...

Not my call... just pointing it out.

Re: Digital Sidecar relay ports: correct voltage?
 

Electromagnets are legal, but not as part of an integrated purchased assembly.

http://forums.usfirst.org/showthread.php?t=14205


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Re: Digital Sidecar relay ports: correct voltage?
 

Wow, that's a pretty broad interpretation.
Electromagnets good, Solenoid Actuators Bad.

Make sure you have a printout of that Q&A on hand at all times :)

I just hope you don't get a finicky EE as an inspector.
There could be some big arguments there......

Re: Digital Sidecar relay ports: correct voltage?
 

This Q&A more closely describes what we are doing with the electromagnet:

http://forums.usfirst.org/showthread.php?t=14279

Re: Digital Sidecar relay ports: correct voltage?
 

Yes, that's much more definative. Glad you found/received a clearer answer.

Re: Digital Sidecar relay ports: correct voltage?
 

It's actually a narrow interpretation. A COTS electromagnet is clearly permitted as long as it is not actuating something. A COTS electro-magnetic actuator is not permitted under any circumstances.

The only thing that is not clear is whether a COTS electromagnet is permitted if it is actuating (forcibly moving) something external to itself on the robot. That specific question has not been explicitly addressed by GDC by either of the Q&A responses, since both questions were asking about an electromagnet simply holding something, not moving something.

There have been no arguments about electromagnets used as a holding device, that I am aware of. I don't expect any. The GDC ruling was quite unambiguous.


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Re: Digital Sidecar relay ports: correct voltage?
 

I'm not arguing the ruling... but if you really want to split hairs, how is holding something, and then letting go, NOT an actuator.

What is the purest definition of an "Actuator"?

Seriously, unless you are using the magnetic field to manipulate sub-atomic particles, isn't the whole point to effect the motion of another item... holding, or pushing, or pulling.... in all cases you are excerting a force on another object, causing it to either move, or not move. In the case under siscussion, if the electromagnet is on amd the metal is being "held" in place, and then some external force (robot) did pull the metal away from it, and then than force was removed, wouldn't the electromagnet pull the metal back into place again... So although it would "normally" be holding it in place it may actually move it under some unforseen operating circumstances.

So... holding or pulling or pushing.... seems to me it's an actuator no matter what it's doing. Fortunately the GDC has ruled otherwise... but it's far from "unambiguous" in my more "generic" view.

Re: Digital Sidecar relay ports: correct voltage?
 

I don't want to split hairs.


Just telling you what the GDC ruling is. The ruling was clearly that if you are using a COTS electromagnet to just hold something, and then let it go, it is legal. That much is quite clear. If you want to call that an actuator, I don't mind.


You may call it an actuator if you like. But other people may misunderstand you.


The GDC ruling is clear as far as how they have specifically permitted electromagnets to be used. Whether or not it is permitted to use an electromagnet in different contexts is a different question, as yet unresolved AFAIK.


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