Re: [Emc-users] MESA 7i43

[Andrew <par...@gm...>]

2011/7/3 andy pugh <bod...@gm...>:
> On 3 July 2011 12:06, Andrew <par...@gm...> wrote:
>
>> 1. There are several 7i43 models. I guess 7i43-U-4 is what I need?
>
> Probably. The bigger FPGA gives a wider choice of firmwares, there are
> some functions that won't fit in the smaller one. EMC2 only supports
> the parallel interface.
>
>> 2. Do I need any breakout boards, or servo drives and other stuff can
>> be connected directly to 7i43?
>
> You can connect direct to the 7i43, though it isn't the most
> convenient of headers. Boards like the 7i33TA make wiring easier (and
> include the PWM to voltage conversion, if you are not desperate to do
> that yourself)

Thank you, Andy.
I'd prefer not to mess with homemade conversion, but 2 x 7i33TA =
$160, not so cheap.

> SPI is a problem. There is an experimental framework that supports the
> Mesa Buffered SPI interface, but you would need to write a driver in
> comp for your specific encoders. When I say "experimental" I mean that
> it isn't even in the development version of EMC2. I can send you a
> patch file.

Well, considering the current SPI situation I guess it is wise to buy
single 7i43 card first for step/dir mode, then try to connect SPI
encoders and if it's OK consider 7i33TA purchase.
By the way, in case 2x7i33TA connected, where to connect SPI encoders
and other stuff? Manual says that 7i33TA only has quadrature encoder
inputs.

2011/7/3 Viesturs Lācis <vie...@gm...>:

> To move to analog control I have 7i43-U-4 and 7i48 daughter card (but I
> have not yet installed them). 7i48 has 6 PWM-to-analog outputs and 6
> encoder counters. But those inputs will not support SPI encoders.
> If there is a chance to change encoders to "normal" quadrature ones,
> this  might be exactly what You need - time savings would be
> significant, which might provide also cost benefits, compared to DIY
> pwm-to-analog converter.

Thank you, Viesturs! That looks better for $108 instead of $160. One
7i48 gives 6 outputs and one port remains free on 7i43 for spindle PWM
and other IO.
Really, if I find cheap quadrature encoders, I can give up SPI at all,
though it would be kind of challenge.

> You can connect directly to two 50-pin connectors of 7i43. I put
> 7i42TA in the welding robot to make the wiring easier. AFAIK 7i42 also
> provides some protection from overvoltage in inputs. If You are
> confident that You do not need that, You can easily do without it.
>
> BTW, if You are not aware, there is a Mesa dealer in Czech -
> www.duzi.cz I find them more convenient than purchasing from US,
> delivery is much faster and total cost (price + shipping) is just a
> little higher.

Yes, I'm going to by from duzi.cz too.

> My personal opinion - use analog signal from the beginning.

If I had quadrature encoders, I'd go this way. But I decided to start
from single 7i43 for step/dir first. In case of SPI success it might
be no sense to spend money for daughter cards at all, because half of
their functionality (encoders) won't be needed.
By the way, DMM Tech has optional SPI control for servo drives. I
wouldn't need that nasty pwm-to-analog conversion, if purchased those
drivers =(

So, I'm going to order 7i43-U-4 + 1m 50 cores cable + 2 x 50pin
connectors. Anything else necessary, from your experience?

Andrew