Believe or not, I am only marginally closer to an answer to the problem I've been working on with the sabertooth not tuning. I am nearly at the point where the men in white coats will come and take me away. I've changed everything more than a few times. I swapped around the Sabertooth and kangaroo and proved all three of them to be working, except for one roo which seemed to be faulty. I replaced the roo but the fault remains. I also replaced the gear motor / encoder, also no luck. I have lost count how many times I have checked all the wiring and the limit switch operation.

Now that I have a spare motor, I tried connecting it directly to the sabertooth and plugging the encoder directly into the roo and simply bridging out the limit switch terminals to simulate N/C contacts. This worked and I was able to start a tune and indicates there might be a problem in the permanent wiring in the robot. I then took out the bridge on the limit switch terminals and plugged in the limit switches I have been using in the robot and I was still able to start a tune. This proves the limit switches and wiring are OK as well.

The encoder wiring has been extended from the motor to a plug that's mounted on the top of the CSS and then continues to the roo mounted in the CSS. I have checked continuity of the encoder wiring via the plug with a multi-meter because I was thinking there may be too much resistance due to cable length and the plug, but I only got a reading of about 0.15 ohms on all cores. I'm not sure if this is the cause of my problems or not, but I figure the only way forward is to rewire everything and also try a better quality plug

This problem has been really frustrating because up until the original 2x12 sabertooth died, everything was working perfectly

Steve tired

Crap Steve, this sucks. What encoder are you using? Some require a pull up risistor it the cable length is too long.

Have you tried completely removing the limit switch circuit and trying to do a Teach Tune?

In the end you may be right. Most issues I've come across in troubleshooting all kinds of devices end up to be connector or wiring related.

Hi Dave,

Yeah, I've tried the Teach tune several times. It still comes up with another error code (2 flashes - "System Range. The system can’t tune in the range provided or reached one of the limits. Make sure you started the tune in the center of motion"), even though the limits are not even connected.

If the motor works when directly connected to the sabertooth but not when connected via the normal wiring installed in the robot, then there must be a fault in the wiring or plug. Its so frustrating because it was all working with the wiring the way it is with the previous sabertooth

Anyhow, I'm off to work now, Catch ya soon mate

Steve.

This is the motor/encoder combo i'm using. https://www.robotgear.com.au/Product.aspx/Details/724-131-1-Metal-Gearmotor-37Dx52L-mm-with-64-CPR-Encoder If this encoder ends up needing a pull up resistor due to cable length, what value and how would it be connected?

Ahh, this is a Hall effect encoder. I have no knowledge of these. I'd suggest contacting the manufacturer to see if the distance you're running your wiring is an issue for this encoder. If so they may have a solution.

If I remember correctly, everything works outside of the robot (and with shorter wiring )? When using the robots wiring this is when you get the errors?

On the other hand, the roo has different error codes for feedback and limits. You could give DE a call and get their advice.

I don't have anything to add in regards to the saber tooth configuration / however, I would recommend checking the grounds. All grounds must be common and shared amongst any electrical device that is connected together. Many issues with unusual electronics are due to lack of common ground.

Just a thought

Also, as Dave said it might be worth contacting DE

I am at the end of my rope with this sabertooth issue. I have completely rewired the whole circuit. I have replaced the plug in the middle of the circuit with a 15 pin VGA plug and socket hoping for a better quality connection. I have replaced every other component including the motor, sabertooth and kangaroo. I have confirmed the continuity of each wire and every in the circuit while all plugged together. I have confirmed the operation of the limit switches by measuring across the terminals on the rear of the kangaroo to confirm the limit switches are closed and then operating the limit switches and confirming the limit switches then open.

The error I get when I try to auto tune is six flashes on the kangaroo which is according to the kangaroo manual is a limit switch is fault but I have proven the limit switch circuit is fine by disconnecting the new motor and connecting a second identical motor directly to the sabertooth ( this is the original motor I was using but replaced with the new one in the hope that would fix this problem ) With the motor connected directly to the sabertooth/kangaroo, and the limit switches in the head section still connected to the roo and the auto tune will start. While the motor was connected directly to the sabertooth and the auto tune works, I extended the encoder wiring with 1 metre servo extension leads thinking the issue may be encoder signal voltage drop, but it still worked.

I have proven the new motor itself in the head section works by disconnecting the wires from the sabertooth motor terminals and connecting across a battery and the motor runs.

I am clutching at straws here, but the wires from the VGA plug are connected to the motor wires by in-line twisting and soldering with heat shrink over the join. This doesn't sound possible to me but, is it possible the soldered connections are causing the issue with feedback from the encoder?

There has been mention of the possible need for a pull up resistor, Does anyone know if this will help and how and where to connect it?

I hope someone can help me as this thing is doing my head in. stress

Steve

Ah man Steve. I was hoping that not hearing from you meant that you got this worked out. I guess not.

This may be just a stab in the dark but I see you have a big speaker mounted right next to where your wiring from the encoder passes. If your using a Hall effect encoder maybe that big magnet from the speaker is messing up the signal. Try removing the speaker and any other magnetic devices and see if that helps.

I'm sure you will get this fixed. You have a very solid and well built system there. You just need to figure what is keeping the dam auto tune to work.

Do you have your old working tune saved? Maybe you can load it into the new roo and manually adjust some of the settings if needed in the DeScribe Software. That way you don't even need to do an auto tune.