Talon SR vs SRX

[jtaylor991]

Hello,

I made the suggestion that our team purchase one or two extra Talon motor controllers to have on hand. I checked both AndyMark and Cross The Road's website and they both say the Talon SR has been discontinued. AndyMark said it was being replaced by the SRX. The pictures for the SRX look totally different -- whole other beast.

This concerns me:

Would they be compatible with our Talon SRs that were included in the 2015 kit of parts? (or are those SRXs? They only say SR) If we have them as backup, could we just hot swap one in, connect the PWM, and be on our way?

I saw someone mention the code from NI being wrong concerning mecanum drive in a forum post (although the forum post was deleted in the past few minutes). We're using mecanum (Cartesian) drive, so this is something I/we would like to know about as well if anyone has any sources on that.

Thank you for any and all of your time!

Jackson Taylor
RoboJackets FRC Team 1827

[Ether]

Originally Posted by jtaylor991

I saw someone mention the code from NI being wrong concerning mecanum drive in a forum post

When you see a post like that from someone who has a total of 1 post, you should take it with a grain of salt.

[NWChen]

Originally Posted by jtaylor991

Would they be compatible with our Talon SRs that were included in the 2015 kit of parts? (or are those SRXs? They only say SR) If we have them as backup, could we just hot swap one in, connect the PWM, and be on our way?

Both the Talon SR and the Talon SRX support PWM control. Having said that, wiring the Talon SRX for PWM control requires some modification of either the PWM cable or the Talon SRX signal cables. Once you've made those modifications, hot-swapping either motor controller (and keeping in mind that the Talon SRX doesn't support the fork connectors you might commonly use with the Talon SR) should be simple. Refer to section 1.3.3 on the User Guide for more information.

I saw someone mention the code from NI being wrong concerning mecanum drive in a forum post (although the forum post was deleted in the past few minutes).

mecanumDrive_Cartesian() shouldn't have any issues with the Talon SR or Talon SRX. Issues with the method and CAN Jaguars were reported.

[RufflesRidge]

Originally Posted by NWChen

Issues with the method and CAN Jaguars were reported.

And reported fixed in the 1-16 update: http://wpilib.screenstepslive.com/s/...ates-changelog

C++\Java - Added support for CAN Jaguar Sync Groups in RobotDrive

[jtaylor991]

Originally Posted by Ether

When you see a post like that from someone who has a total of 1 post, you should take it with a grain of salt.

My bad, I normally would have looked at that but I was in a bit of a hurry. That might explain the post being removed.

Originally Posted by NWChen

Both the Talon SR and the Talon SRX support PWM control. Having said that, wiring the Talon SRX for PWM control requires some modification of either the PWM cable or the Talon SRX signal cables. Once you've made those modifications, hot-swapping either motor controller (and keeping in mind that the Talon SRX doesn't support the fork connectors you might commonly use with the Talon SR) should be simple. Refer to section 1.3.3 on the User Guide for more information.



mecanumDrive_Cartesian() shouldn't have any issues with the Talon SR or Talon SRX. Issues with the method and CAN Jaguars were reported.

OK, so it supports the functionality but does not simply have a direct PWM jack like the SR. That's good to know, thank you. I'll look into these modifications and see if we want to move forward with that.

If not, would other controllers like Jaguars be able to be subbed in instead? If so, what would I need to do in code to allow this? If not, should I look into buying used SRs or just rely on FRC Pit Admin spares? It's a serious bummer (and odd decision IMO) that FIRST shipped a discontinued product in the KOP. I understand finding a use for old stock, but really, come on...

I'm using LabVIEW by the way. I'm going to look into using Java (or C++) later on.

[Chris_Ely]

Another option is the Victor SP. It is similar to the Talon SRX; both were jointly developed by Vex and Cross The Road Electronics. The Victor SP has a direct PWM input, but lacks the advanced capabilities associated with CAN that the Talon SRX has.

[ozrien]

I think either Talon SRX or Victor SP are good drop in replacements for Talon SR.

All three use the same output frequency (15.625KHz).

All three support PWM, though the SRX/SP have a common default pwm cal (1ms,1.5ms,2ms) but that's easily fixed by calibrating your pwm signal to better match your Talon SR (assuming you also calibrate your SRs). Basically if you always calibrate your motor controls, they should be close enough.

All three perform synchronous rectification.

All three support brake/coast select.

(and keeping in mind that the Talon SRX doesn't support the fork connectors you might commonly use with the Talon SR)

What's a fork connector?

[ozrien]

One more - they all three have a 4% deadband.

[NWChen]

Originally Posted by ozrien

What's a fork connector?

One of these, which gets attached to a Victor 884/888, Talon SR, or Jaguar via the included screw terminals. Since the Victor SP/Talon SRX this year have wires builtin, these connectors no longer readily connect to either motor controller.

[Ether]

Originally Posted by NWChen

One of these...

I believe that's more commonly known as a spade lug.

[Michael Hill]

The SRX also supports SPI, but I don't believe I've seen anywhere in the rules stating we can actually use it for motor control.

[cgmv123]

Originally Posted by Michael Hill

The SRX also supports SPI, but I don't believe I've seen anywhere in the rules stating we can actually use it for motor control.

R59 says the Talon SRX must be controlled by CAN or PWM.

[Addison4300]

This is our teams first year to use Talons, in the past we have used Jaguars and Victors in combination. What are the major differences between Talons and Jaguars and Victors?

[jtaylor991]

Originally Posted by Addison4300

This is our teams first year to use Talons, in the past we have used Jaguars and Victors in combination. What are the major differences between Talons and Jaguars and Victors?

Fans are optional, they are sealed so you don't need to worry about metal shavings "pollution", they have a choice of coast or brake mode set by a jumper, and they're smaller. That's my understanding.