Re: Anderson PowerPole for CAN bus?
 

The connector is rated at 15amp. You're not actually going ot be putting 15 amps through it. There's no rules preventing you from using connectors rated for higher currents than required in your application.

My guess is that the 15A connector was suggested because it's the smallest gauge connector available for the power poles. You're likely to have trouble crimping a larger connector on such small gauge wires, and if you succeed without breaking the wire, you're likely to have failures down the line.

Re: Anderson PowerPole for CAN bus?
 

Very interesting thread. We're going to try out the APPs on our prototype robot since that's what we have right now but if we run into any problems I like the idea of combining these two solutions.

Using the 3 pin versions or the Hansen Hobbies locking polarized connectors would allow you to still use PWM if you wanted to but also prevent you from flipping polarity on accident. The 3 pin housings aren't much more expensive than the 2 pin. You can daisy chain with out much hassle or the need for special connectors. From one of the non-talon nodes you would just need a few wire pairs with just the male or female ends of the connectors attached.

Re: Anderson PowerPole for CAN bus?
 

Allen,
We like the Victors and will likely use them for this season. There are a variety of other connector solutions available through outlets like Digikey (who is a big FIRST supporter in Minnesota) and others. As Don has pointed out above, solutions need to maintain buss impedance in some fashion (it is a transmission line interface after all.)

Mb,
There is relatively little current flow in this bus so it does not come under the wire gauge rules. Please remember that the those rules relate current protection to wire size. A dead short on the CAN buss will not burn up the wire.

I would use a locking connector of some type that is easy to terminate and difficult (read as 'impossible') to connect backwards. The RJ-11/45 used on the Jaguar is a pretty reliable device, crimpers are available everywhere for cheap and the connectors are easy to get. As always, I tend to discourage solid wire on moving devices but there is plenty of stranded wire options for these connectors. Spend the money for the right connectors and crimper if you want reliable operation.

Re: Anderson PowerPole for CAN bus?
 

So is the simple solution of wire nuts not the way to go?

Re: Anderson PowerPole for CAN bus?
 

I would not use wire nuts.
If you have access to DB-9 hardware, that is not a bad way to go either. Easy to terminate, crimp or solder, with standard hardware everywhere, including IDC (ribbon cable) termination.

Re: Anderson PowerPole for CAN bus?
 

The CAN bus connections are critical just like many others such as the power to the RoboRio. Since the CAN bus wires are integral with the Talon SRX, teams who use a crimp to join two of them together will have to cut the wires when re-using the motor controllers, making the wires shorter each time. The wires can be soldered and then un-soldered but soldering has it's own problems. This is where teams have to learn to do a good job and learn to enforce an adequate level of Quality Control (treat them like one would treat the braking system in ones car).

The CAN Bus wires are much smaller than the wires normally used with the Anderson connectors. They may have to be folded over more than two times for the crimp to hold the wire in properly. If not done right, the wire may pop out with a slight pull later. I am also concerned with the relatively high un-mating force of the Andersons. Many people pull on the wires to un-mate connectors even though that is bad practice. With the 14-10 AWG wire normally used, the wire and crimp have a decent chance of staying together. With the small CAN wires, I can foresee people breaking the wires.


We just started using them at work and got them from Home Depot or Lowes until our regular wholesale suppliers got them in stock for us.



Some fairly expensive equipment or some very specialized 3-D field-solver software would be needed to determine, objectively, the effect of a connector on the CAN Bus impedance. In general, a connector with contacts that have dimensions and physical configuration most similar to the rest of the transmission line (the wires) will probably introduce the least disturbance to the impedance and the least corruption of the signal. Thus, the locking connectors from Hansen, or something like them, are probably the best solution. An added bonus is that the "Latching Male Housings" from Hansen seem to have a shroud so that when male pins are inserted into them, they cannot short to anything unless one pokes something into the end.

http://www.hansenhobbies.com/product.../pt1in_lp_1x3/

Re: Anderson PowerPole for CAN bus?
 

The CAN Bus wires that come with the Talon SRX's are probably larger than the wires in ribbon cable and might not work with IDC DB-type connectors. There are IDC connectors for larger wires but it would take some research to find some that are readily available in the small quantities that FRC teams would want to buy (i.e. no need to order in 1000's).

It just occurred to me that we may be using some locking IDC connectors with 18AWG wires at work. I will have to have a look around when I get to work today.

Re: Anderson PowerPole for CAN bus?
 

We have had some interesting debates about this while trying to define the best practice for controller locations. It probably warrants it's own thread but I'm too lazy to start one. We currently have defined 8 subsystems here we might use closed loop control with Talon SRXs. The side debate is whether to distribute them close to the motor / feedback location with a longer and more vulnerable CAN bus or place them in a group with a short CAN bus and longer motor and feedback leads. I leaned toward the former but lost the debate and the 8 Talons are in a small group which my be best as a CAN wire problem takes down the whole bus where a feedback sensor wire affects one device. As a side note we have been distributing the CAN bus around our robots every year since 2010 with minimal problems after debug.

To the point of the thread, since the SRXs are close to each other, we pulled out the terminal blocks from past KITS of PARTS (I think they were donated by AutomationDirect) and used them to daisy chain through. It works well for the layout.

As for the feedback sensor wiring, I had already ordered the latching plugs from Hansen Hobbies that Peter mentioned above. I have been using them for months on my 3D printer without problems. I'm passing the hot end temperature thermistor through one that is constantly being jogged at high speed and it has caused no problem. I wouldn't be afraid to use them on the CAN bus but I use grey wire nuts on small wires all the time too.

Re: Anderson PowerPole for CAN bus?
 

Has anybody looked around at JST connectors?

Re: Anderson PowerPole for CAN bus?
 

CAN connector coming soon, see attached image.

Re: Anderson PowerPole for CAN bus?
 

any idea on pricing?

Re: Anderson PowerPole for CAN bus?
 

For some authoritative documentation on connectors for CAN, see section 4.6 of:

http://www.ti.com/lit/an/slla270/slla270.pdf

Thanks to Ether for digging this link up and posting on another thread!

Re: Anderson PowerPole for CAN bus?
 

Re: Anderson PowerPole for CAN bus?
 

The best connectors have a profile similar to the diameter of the wire. The reflections occur at impedance mismatches and the impedance of the connector is largely a function of the geometry. In an ideal world the wire and all the connectors would have the same impedance at 1Mhz and the terminations at each end would be 2X that impedance, nominally 50-60 ohms for CAN. Note that this is impedance, not purely resistance.

We have used PWM connectors and Molex connectors (for 20AWG wire) with zero issues running 9 Talons. Powerpole pins are overkill for the current and are larger than 20AWG wire - I would shy away from using them.

Good luck!

Re: Anderson PowerPole for CAN bus?
 

Looks like a good solution - I like it!

Personally, I'd love to see that block be part of the TalonSRX if a hardware rev gets performed in future years.

For that matter, I really wish the 10-pin "encoder connecter" were also weidmuller connectors -- the 5x2 .05" header connector is less than optimal for interfacing to directly.