Re: [CAD_CAM_EDM_DRO] Anyone using JR-Kerr?

I have not used the board you are talking about, but I have used their
picstep chip, and am not happy with how they did things. The software I
wrote, the software others wrote, just was not reliable. And I actually
had two sets of chips that acted differently. Both sets worked with his
example software, but with the software we wrote, one set of chips would
turn one way, the other set would turn the other. That was very hard to
find! I really should contact him and let him know... but that project is
over and I don't want to think about it any more.

I don't like how his commands are non-ASCII (you can't just type them in a
terminal window or use a terminal program to "spy" on the serial stream),
and I don't like how he addresses the different nodes on his (sort-of)
RS-485 network. He uses an RS-485 twisted pair for the data communications
(good idea, differential signals help eliminate common mode noise),
BUT! He uses a single ended, ground referenced, "address" line daisy
chained from node to node, for addressing. This one line eliminates any
advantage of the RS-485 network.

Back then, I don't think he had a coordinated move stepper driver chip,
only his servo chip, but I think he does now. He had/has a g-code
interpreter to run his servos, though. If you go this route, you are
stuck with his g-code controller, because I don't think anyones software
will ever speak his controller's language.

If the new board now takes step and direction, that really would be a step
in the right direction! That would make it much easier to use his products
with the kind of controllers that us CNC people are use to.

Just my opinions,

Steven Ciciora

At 01:26 PM 11/10/2004 +0000, you wrote:

>I have been looking for cheapish command based motion control for a
>project I am working on in the department. I was looking at the 3-
>axis brush/brushless servo drives by JR-Kerr and noticed they can
>also be driven with step and direction which interesting for home
>use. Just wondered if anyone is using these?
>
>Graham
>