VersaPlanetary Integrated Encoder without Talon SRX?

Technical Electrical
1

So I am interested in using the VersaPlanetary Integrated Encoders next year to control some of the mechanisms on my team’s robot.

However, my team only uses Victor SP’s for our motor controllers. Is there any way to use the Encoders without the Talon SRX’s? On VEXPro, the description says:

The VersaPlanetary Integrated Encoder can be plugged directly into the Talon SRX by using the Talon SRX Data Cable, or you can solder on your own leads for plugging into the roboRIO.

What does soldering our own leads require? And where would they plug into the RoboRIO?

2

We didn’t use these on 687 but I believe these breakout boards work: http://www.vexrobotics.com/217-4398.html

3

These are for wiring an encoder to the talon srx.

4

Section 5.4 of the Magnetic Encoder User Guide describes some ways to do this.

You can solder you own wires to either of these breakouts:

Disclaimer: I have never used these breakouts, so make sure you have someone double check this advice.

The first one is designed to be used the other way around (attaching a non-standard encoder to a Talon SRX), but the manual states that it is okay to use it for your application. You would wire 5V and ground from the roboRIO to the appropriate labelled pads on the breakout, while the A and B pads should be connected to two digital inputs on the roboRIO. Then it can be used in code like any quadrature encoder.

If you use the second breakout, you can do pretty much the same thing, but you have to figure out which pads correspond to the A and B channels of the encoder.

Also, AFAIK, there is no way to use the absolute position mode of the encoder without connecting it to a Talon SRX.

5

Confirming that this works. My team used several VersaPlanetary Integrated Encoders wired this way this year.

I think you can get the absolute position signal by using http://www.vexrobotics.com/217-4401.html but I haven’t tried it personally.

6

Another option is to solder directly to the ribbon the cable. It saves you from having to buy the breakout board and allows you to connect two encoders per ribbon cable (you cut them in half in order to solder to them). A pin diagram for the ribbon cables can be found on page 5 of this document: https://content.vexrobotics.com/vexpro/pdf/SRX-Mag-Encoder-User-Guide.pdf .
When soldering these I highly recommend using flux and be sure to individually insulate each wire with electrical tape or heat shrink.

7

The absolute position mode uses a PWM signal rather than an analog signal, so I don’t think that would work. You would have to find a way to decode the PWM signal on the roboRIO.

8

read posts 5, 6, and 7 of this thread:

9

^ This is wrong

Since the PWM signal goes from 0 to 100% duty cycle, I assumed they were just using a filtering circuit to smooth it into a signal readable as an analog voltage.

Comparing page 5 of https://content.vexrobotics.com/vexpro/pdf/SRX-Mag-Encoder-User-Guide.pdf and page 17 of https://content.vexrobotics.com/vexpro/pdf/Talon-SRX-User-Guide-20150201.pdf shows that they actually use different pins. Interestingly, the PWM out actually gets wired to the pin labeled “Quadrature Index”