[Emc-users] MESA 7i43

[Ted H. <las...@gm...>]

Andrew -
You noted that you are using step/dir into servo drives - does it follow 
that your servo drives require those SPI interfaced encoders? In the 
servo drives I've encountered, if it has a step/dir mode, the drive is 
an intelligent one and handles the entire PID and feedback loop itself, 
meaning the encoder (or at least halls+) is fed directly to the servo drive.

Although I agree with Viesturs and recommend you go right to analog for 
your "production setup", it's quite acceptable to work with what you 
have first and get comfortable with it.

In that regard (step/dir) it's unlikely that you'd be feeding back 
encoder data to EMC (you're treating the system like stepper motors). 
True, some have succeeded in getting steppers with encoders for 
closed-loop, although it's not the typical implementation.

Does your drive by chance send out a buffered or recreated quadrature 
signal? Some drives do, as they are used for encoder following 
installations. If it does, you can likely keep the drive-encoder 
relationship as SPI (as the manufacturer intended?) and grab the 
quadrature signal coming out of the drive for EMC when you decided to 
convert to analog command mode......

On 7/3/2011 8:35 AM, emc...@li... wrote:
> Date: Sun, 3 Jul 2011 14:06:24 +0300
> From: Andrew<par...@gm...>
> Subject: [Emc-users]  MESA 7i43
> To: "Enhanced Machine Controller (EMC)"
> 	<emc...@li...>
> Message-ID:
> 	<CAJ...@ma...>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi,
>
> I consider purchasing 7i43 board to control 6 servo drives. First in
> step/dir, later in analog mode (with homemade PWM to analog
> convertors). As long as I have SPI encoders, I'm not sure it is that
> simple to connect them to EMC2 for analog servo mode, but I hope it's
> possible.