Relay Aliases Backwards
 

Has anyone else noticed that the relay aliases for fwd and rev seem to be
backwards?

By backwards I mean, I was setting relay3_fwd to 1 and relay3_rev to 0
and the light on the spike was red.

I fixed it by swapping the defs in ifi_aliases.h

Thoughts? or did IFI just goof?

Re: Relay Aliases Backwards
 

forwards and reverse are separate bits, because you can also turn the relay off

Re: Relay Aliases Backwards
 

Yeah, I was wondering about that. I thought it was my problem - that somebody else has it makes me think it's not. IFI might have goofed, you never know...

Re: Relay Aliases Backwards
 

That might explain why our solenoids weren't working saturday night, and they worked on sunday morning when mentor put black to M+ and red to M-

Re: Relay Aliases Backwards
 

Well...who knows how many times we have hooked our compressor up "backwards" then. The pneumatics manual gave a warning about not putting reverse voltages through the compressor, but i have not seen any problems (the PSI steadily increases, regardless).

Re: Relay Aliases Backwards
 

I have had the same problem. However, I dont believe the aliases are wrong but rather the LEDs are incorrect. Red now means the M+ is at 12v (M- gnd) and Green means M- is at 12V (M+ gnd). I say this beacause I am using a single solenoid which is spring return, so I only power M+, which the red wire of the solenoid is hooked up to. I simply toggle that relay's fwd bit to operate the solenoid and it works. I would not go changing the polarity of your compressor because reverse polarity could seriously damage it.

Re: Relay Aliases Backwards
 

the solonoids are not polarity sensitive - if current flows through the two wires they will trip

and I would be really surprized if the compressor cares which way it runs - the motor makes the piston go up and down - I dont think it cares if it goes down and up instead.

Re: Relay Aliases Backwards
 

I believe the single solenoid was connected to an external ground not on the spike (as we generally do for all our double or single solenoids, but I did not wire it personally). I will have to take a good look at the program, wires, and pneumatics to figure it out.

Quote from the 2004 Pneumatics Manual:
"Ensure that the relay is programmed to provide “forward” power only to the
compressor. Do not reverse the compressor!"

Re: Relay Aliases Backwards
 

I haven't hooked up a multimeter to the relays yet, but I'm almost 100% postive you're incorrect about this. If this were true, it would imply that the robot controller not only tells the relay what polarity to set itself to, but what color to light the LED to. This would require 4 bits of information to represent, and we're attaching the relay to the controller with 2 signal wires. I seriously dobt they implemented a serial communication protocol between the controller and relay.

The claim you made holds some incredibly serious implications... You might want to back such claims up in the future, because even though I'm sure you're wrong, I'm going to have to test this myself because it's not worth blowing out components a week before ship.

Re: Relay Aliases Backwards
 

I tested the relays with the multimeter - when I set relay1_fwd to 1, the spike turns red and the multimeter reads -12v. When relay1_rev is 1, it's green and the multimeter reads 12v. This seems backwards to me...

Re: Relay Aliases Backwards
 

next question: do you have the power to the relay connected correctly, and also the control cable.

Re: Relay Aliases Backwards
 

I also checked a relay with a multimeter today (as I said I would last night) and came the to the same conclusion as steven114. With relay5_fwd set to 1 (relay5_rev = 0 and LED was red), the multimeter common probe on the M- of the spike connected to relay output 5, and the multimeter voltage postive probe connected to M+, the multimeter read -12V. The relay output cable was connected correctly. I also checked the same spike with the common probe on ground. I read 12v on the M- and 0v on the M+. It seems that the IFI aliases are incorrect.

I was wrong about this and my sincere apology to anyone I may have confused. My knowledge of the matter was based on a false assumption. The single solenoid I was basing this on was wired to the M- of the Spike. It was the only one of our 5 solenoids (2 double, 3 single) wired without an external ground (it has been rewired now).

I have rewritten ifi_aliases.h to change the aliases from fwd to rev and visa versa. I loaded the modified program into my bot and confirmed that relay 5 (my compresser) was getting +12V. A zip file with my new ifi_aliases.h file is attached to this post. Hope it helps. I am posting from MOE HQ workshop (not my dorm as usual) so I have get back to work now. Once again I'm sorry.

Re: Relay Aliases Backwards
 

So if our compressor was working right before this, do we dare correct the problem and reverse the polarity?

Re: Relay Aliases Backwards
 

You should be running the compressor forward - it probably was not working right, or something like that.

Re: Relay Aliases Backwards
 

are all your spikes backwords or just one? you might have the relay out ribon on backwords