COMM lost way to many times

[Bruceb]

[Bruceb]

hope this works

[RufflesRidge]

Originally Posted by AllenGregoryIV

The FIRST video on using Weidmuller connectors says 5/8"

The page that video is embedded on contains this note:

The correct strip length is ~5/16" (8mm), not the 5/8" mentioned in the video.

[Bruceb]

From the VRM users guide

Strip wire back ~0.375” (3/8”)

[evanperryg]

Originally Posted by Bruceb

we had several folks look at the fuses and they were deemed OK but I will pull them and insert new ones Thursday.
Thanks

Make sure you smash them in there. Excessive force is necessary for them. Also, make sure the power connections to and from the VRM are done properly. When they're secured the right way, you should be able to pull on them with all of your weight without them moving.

[Zagar]

Ok, not on topic, but I have to ask what kind of tires are those?

And on topic, we too lost comms on our first match this past weekend. We were told that we should not have tinned the wiring going into the VRM....

[Al Skierkiewicz]

Bruce,
I know that this doesn't help you at this point but there doesn't seem to be any strain relief on the power plug for the radio. The barrel connector depends on the "spring force" of the outside contact to hold everything in place. I highly recommend using an adhesive backed wire tie point on the top of the radio. Loop the power wire up to the tie point and then secure with a a small wire tie. This small step keeps the connector from bouncing around and prevents pullout. Tape over the connector to the radio body also works. The antennas for this radio are on the sides of the radio, inside the vents. It doesn't help to have the stainless pneumatic tanks on that side of the radio but shouldn't be a big problem.
There is also the possibility that severe vibration has caused the power plug to pull out of the circuit board. This is easily repaired if the circuit board has not been damaged. The connector is a part of the circuit board that a good hit on the connector could cause a crack in the board. This has the same effect as broken wires. It may work most of the time, but vibration will make it lose the power.
Tinning wires is not recommended for Weidmuller terminals. They depend on the deformation of the strands to give maximum surface area for current to flow. With tinned wire, only the extreme outside surface of the wire touches the contact producing a connection equivalent to a #36 or smaller wire.

[Team34Guy]

We experienced the same thing at both the Arkansas and Rocket City Regionals. After speaking to other teams at Rocket City, the consensus was the power connection at the radio. It isn't as reliable as the D-Link. I found ours had backed out a little over an 1/8" and most likely lost connection briefly when we struck the wall in autonomous. Bomb Squad mentioned that they had experienced some issues prior to competition and had hot glued their connector, they didn't have any further issues with that connection.

It's extremely frustrating to say the least....Especially when Bob starts fussing! (cause usually he's right)

[AllenGregoryIV]

One of the other things that hasn't been metioned is the use of ferrules with the weildmuller connectors. We used them on nearly all of our competition robot connections and have had zero issues.

Here is the white paper from Weildmuller recommending their use with stranded wires.

We import ours from China using Aliexpress but you can also get them from US electronics vendors, ebay, or Amazon.

Make sure you are using the right crimp tool and gauge ferrules. Also get 8mm long ones.

[AllenGregoryIV]

This thread inspired me to write up this document. Anyone have any more suggestions to include.

https://docs.google.com/document/d/1...XrCy1gzk/edit#

[Bruceb]

Originally Posted by Zagar

Ok, not on topic, but I have to ask what kind of tires are those?

And on topic, we too lost comms on our first match this past weekend. We were told that we should not have tinned the wiring going into the VRM....

they are 9.4 inch beach tires. 3 psi and they litterally float over the defenses

[Bruceb]

Originally Posted by Al Skierkiewicz

Bruce,
I know that this doesn't help you at this point but there doesn't seem to be any strain relief on the power plug for the radio. The barrel connector depends on the "spring force" of the outside contact to hold everything in place. I highly recommend using an adhesive backed wire tie point on the top of the radio. Loop the power wire up to the tie point and then secure with a a small wire tie. This small step keeps the connector from bouncing around and prevents pullout. Tape over the connector to the radio body also works. The antennas for this radio are on the sides of the radio, inside the vents. It doesn't help to have the stainless pneumatic tanks on that side of the radio but shouldn't be a big problem.
There is also the possibility that severe vibration has caused the power plug to pull out of the circuit board. This is easily repaired if the circuit board has not been damaged. The connector is a part of the circuit board that a good hit on the connector could cause a crack in the board. This has the same effect as broken wires. It may work most of the time, but vibration will make it lose the power.
Tinning wires is not recommended for Weidmuller terminals. They depend on the deformation of the strands to give maximum surface area for current to flow. With tinned wire, only the extreme outside surface of the wire touches the contact producing a connection equivalent to a #36 or smaller wire.

Al that was an old pic just to show the location of the radio. At the time of our latest comm losses during elims we had a new tighter barrel jack taped in place AND we were running POE. so we had two power sources.
this bot had been gone over by nearly every orange and yellow hat at both Cleveland and Milwaukee. After replacing the barrel jack and installing POE in Milwaukee we had no issues until the last match of quals then it started all over again. Had Pete Thomas doing everything he could think of during elims but he found nothing.

is it just the 706 curse? 6 time finalist in the last 4 years.

Thanks

[Bruceb]

one other thing
we NEVER lost comms during extreme contact with another robot or flying over defenses. It always happened when just starting to cross the defense and even happened when crossing the low bar once.
I am beginning to think a static discharge may be part of the problem as we noticed a static discharge when crossing defenses on the practice field.

[AllenGregoryIV]

Originally Posted by Bruceb

From looking at logs and reported observations from the FTA's they see the radio rebooting. Immediately after they see the radio return they see the RIO so the belief is that the RADIO is the only think rebooting as the RIO takes longer than the radio and would not show up immediately after the radio if it was also booting.

Do you have the driver station logs from those matches that you can post?

There is also a system log file you can pull up using the RoboRIO webpage as well. We had a problem at Bayou were we were seeing the RoboRIO just crash for no reason (not our code but the whole RoboRIO, as in it stopped even showing up as a USB network adapter to computers once that crash happened, we never found the problem and just swapped RoboRIOs)

[Bruceb]

I will see if I can have our programmers post those from finals matches.