Relay Aliases Backwards

[The Lucas]

Originally Posted by blindguyinanorg

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

All spikes run backwards (Red light when relay forward bit is set). Relay 5 was just the one I tested beacuse it is my compressor and the easiest to test. I needed to comfirm that the red LED on on these new spkies was correct and the compressor was running on -12V (I should have checked that before posting anything but that was my mistake). The single solenoid I was previously talking about is now wired correctly to M+ and external ground. It runs perfectly by setting relay3_fwd=1 in my corrected (ifi_aliases.h) code.

And as I prevoiusly stated

The relay output cable was connected correctly.

and that applies to all the 3-pins cables. Unlike before, I have now check and double checked every part of the system (program, electrical, pnematics). Before I was operating with only the knowledge of the program (I am in charge of that) and the wiring directions I gave the electrical team.

[Andy Brockway]

I would like to confirm that the the alias's are backward. Relay fwd should be green light, ours was red.

My question is has IFI released a default program that is correct?

[QueBall]

Originally Posted by Ryan Cumings

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

There are two reasons why the manufacturer of the compressor would like the polarity observed for the compressor motor.

A) The fan in the motor was designed to move the most air with the least noise/power when turned in one direction only(axial fans). That direction will be when you observe the correct polarity. (result- motor will run cooler and longer)

B) Almost all series wound DC/AC universal motors or PM DC motors have the commutator shifted with respect to the main magnetic field to minimize commutation arcing. So they are most efficient when turning in the direction of the default polarity( e.g. the recommended polarity). This is the reason why the motor will not produce the same rpm/power in either direction. (Also, a radial fan operates equally well in either direction, an axial fan (like the compressor has, does not.) When such a motor is reversed, the commutation can be seen to arc more than the forward case, this arcing will cause the brushes and commutator life to be reduced, the commutator temperature to rise. Further, the arcing represents energy lost and hurts the overall efficiency of the motor. (Efficiency is what you get/what you pay for...)

Motors can be designed to work the same in either direction, but at an overall loss in efficiency.

So, bottom line: wire the compressor backwards will work, but will run hotter, use more power and produce less work, and will have a shorter life than normal.

[InnovationFirst]

We at Innovation First have confirmed the problem you have noticed. The root cause is that the silkscreen labels (REV/FWD/GND) on the Robot Controller are incorrect, and the aliases in the Default Code were set to match them. The simplest fix is to swap the reverse/forward aliases in ifi_aliases.h, as some of you have already done, and to ignore the REV/FWD/GND labels.

Another option is to swap the connections on the M- and M+ outputs of the Spike Relay Module to achieve the correct polarity.

New Default Code with these aliases fixed will be on our web site soon. A note will also be placed in the 2004 Robot Controller Reference Guide regarding the incorrect labels.

Regards,
Innovation First, Inc.

[Ryan Cumings]

Originally Posted by QueBall

There are two reasons why the manufacturer of the compressor would like the polarity observed for the compressor motor.

A) The fan in the motor was designed to move the most air with the least noise/power when turned in one direction only(axial fans). That direction will be when you observe the correct polarity. (result- motor will run cooler and longer)

B) Almost all series wound DC/AC universal motors or PM DC motors have the commutator shifted with respect to the main magnetic field to minimize commutation arcing. So they are most efficient when turning in the direction of the default polarity( e.g. the recommended polarity). This is the reason why the motor will not produce the same rpm/power in either direction. (Also, a radial fan operates equally well in either direction, an axial fan (like the compressor has, does not.) When such a motor is reversed, the commutation can be seen to arc more than the forward case, this arcing will cause the brushes and commutator life to be reduced, the commutator temperature to rise. Further, the arcing represents energy lost and hurts the overall efficiency of the motor. (Efficiency is what you get/what you pay for...)

Motors can be designed to work the same in either direction, but at an overall loss in efficiency.

So, bottom line: wire the compressor backwards will work, but will run hotter, use more power and produce less work, and will have a shorter life than normal.

So in other words, we should correct the problem even if it appears to be running correctly as of this moment.