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Hello,

my RoboClaw 2x5A has just arrived and I have a couple of newbie questions.

1. What kind of connector(s) should I get? I'm planning to use packet serial mode and the encoders. What are the exact pin distances? 2.45 mm? 2.5 mm? Does it matter ?

2. What kind of encoders can I use on my motor? I'll have speeds from 0 to about 6000 rpm. I might also be able to put one on the working shaft of the spinning wheel (that's what it's going to be), where it would have to measure up to 3000rpm.

Thank you!

Thomas

Question 1 can be considered solved. I gutted one of the ancient computers that I seem to be attracting.

I'd be grateful for input on the encoder question -- Thomas

I know it works with these: http://www.lynxmotion.com/p-448-quadrat ... cable.aspx

Thanks Kurt!

So I feel the GP1A30 with a 60-ticks-per-revolution disc might work too. I'm not so sure about the max. frequency that is given in the datasheets. In the one for the GP1A30 it says "max response frequency = 5kHz", on the vendor's site mention is made of "max switching frequency = 10 kHz". Lynxmotion say about their encoder "Frequency = up to 30khz". How do I calculate the max rpm with all that? Is there a limit to the frequency the RoboClaw can handle?

All the best -- Thomas

The current roboclaws can handle around 125000 pulses/second. Multiply your encoder count by your motors max rpm(not the gear shaft output, but the actual motor rpm) and divide by 60 to get the pulses per second. If you know your gear shaft rpm but nor your motor rpm, then multiply the gear ratio by the gear shaft rpm to get the motor rpm.

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Thanks Nathan!

Almost there Just to make sure: Lynxmotion says about the abovementioned QME-01 encoder:

We're talking about the "quadrature counts", not the cycles per rev., right? So that, for example, the QME-01 would be good up to

(30,000 pulses per second) times (60 seconds in a minute) divided by (400 pulses per revolution) = 4,500 rpm max shaft speed.

On the other hand, the recommended motor (this one) has an output of 200 rpm and a transmission ratio of 30:1 which comes out at a motor speed of 6000 rpm. Which would be way outside the encoder's limit, wouldn't it?

All the best -- Thomas

Internally the encoder is updated every 125 times a second from the CPLD. In between the CPLD does the count and it has a 12bit counter. So 4096 * 125 = 512000 / 4 gives 128000 pulses per second. I said 125000 to add a little room for overshoot. SO when I said 125000 I ment pulses not edges.

I'm pretty sure that encoder is made by US Digital. In the real world that motor with that encoder running at 12v will hit a max of around 60000 quadrature edges per second. So it will be seeing about 15khz pulses at max speed. I may be a little off on the numbers since I haven't done max speed tests in a while.

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Sorry, you lost me about here:

Maybe it's a vocabulary problem; English is not my first language. I'm still not sure how these edges and pulses translate into the "cycles" and "counts" of the encoder description quoted above. Or what the frequency mentioned there means. A frequency is the number of occurences of something per unit of time. But what something is meant here? Candidates are: counts, cycles, edges, pulses ...

All the best -- Thomas

quadrature signals are 2 over lapping pulses. Each pulse has a front and back edge. So you can count edges, 4 per quadrature pulse. Or front or back edges only(2 per quadrature pulse) or just the pulses. This gives 4x,2x or 1x counting. We use 4x counting always. If your encoder has 100 pulse per rotation then there are 400 edges.

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Thank you Nathan.

I've now got this Motor (Escap 28D2R) with an encoder that gives 144 pulses per revolution and uses 5V DC. Now here's my next problem:

The first line I understand

Then, after some reading of Wikipedia, I guess that:

Pin 3 = Kathode = GND
Pin 4 = Anode = +5V

And after that I'm running out of pins, because the RoboClaw only has A and B left, one pin for each channel. So what are these emitter and collector Pins?

My apologies for my (probably) absolute beginner questions!

Thanks for your time -- Thomas

PS: The above quote is all the "datasheet" I could find on the net.

I expect anode and cathod are the normal power pins(+-) on the encoder header. emmiters are IR leds on most encoders so these should go to power. Check the datasheet if you have one to see if you can just put 5v in directly or if you need to current limit them. You can probably put a 390 ohm resistor in series without reducing their output enough to not work. Collectors are the A and B pins most likely. These should output highs and lows depending on the position of the encoder wheels.

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