Jags and CAN bus

[waddell]

When using the CAN interface with Jags and rotary encoders for speed sensing is there a maximum limit to cycles or pulses per revolution?

We are assuming that both of these US digital encoders, from AM, will be compatible: E4P-250-250-N-S-D-D-B and E4P-360-250-D-D-D-B.

Just want to make before we order.

Thanks,

[Joe Ross]

Per the Jaguar datasheet, the jaguar can handle 1 million transitions per second.

[Ether]

Originally Posted by waddell

When using the CAN interface with Jags and rotary encoders for speed sensing is there a maximum limit to cycles or pulses per revolution?

We are assuming that both of these US digital encoders, from AM, will be compatible: E4P-250-250-N-S-D-D-B and E4P-360-250-D-D-D-B.

Just want to make before we order.

Yes, there are limits, in the encoder electronics.

What are you trying to measure the speed of? What do you expect to be the approximate maximum speed of that?

[waddell]

Thanks for the quick reply.

Had missed that in the datasheet.

[waddell]

Ether,
I get your jist.

1M transitions disappears rather quickly when utilizing an encoder sending 360 cpr. Worst case of the 2 I listed: 1M/360=2777.

We plan to use encoders on 4.67/1 CimpleBoxes with CIMs. Max output rpm would be in the 1137 range.

Looks like we'll be safe.

[Joe Ross]

Originally Posted by waddell

1M transitions disappears rather quickly when utilizing an encoder sending 360 cpr. Worst case of the 2 I listed: 1M/360=2777.

We plan to use encoders on 4.67/1 CimpleBoxes with CIMs. Max output rpm would be in the 1137 range.

2777 revolutions per second is a lot faster then 1137 revolutions per minute. It's 2 orders of magnitude.

[Ether]

Originally Posted by waddell

Ether,
I get your jist.

I'm not sure you did.

The E4P electronics are good up to 10000 RPM for the 360 CPR model. That's what I was referring to in my previous post.

We plan to use encoders on 4.67/1 CimpleBoxes with CIMs. Max output rpm would be in the 1137 range.

As for the Jag, it can handle 1 million transitions per second (Joe's post). That's 1μs per transition.

For the E4P 360 CPR, there are 720 transitions per rev on each channel.

That's 1440 transitions per rev if you are using both channels.

The attachment shows the μs per transition for single-channel and 2-channel (quadrature) at 1137 RPM for the tolerances specified in the E4P datasheet.

The worst case (2 channel quadrature with max phase error) is 12.2 μs

So it appears that the Jag's sample rate is more than adequate to sample all transitions of an E4P 360 at 1137 RPM, even at worst-case phase tolerance with 2 channels in quadrature.