Re: cheap retrofit with the Allegro UCN5804B chip

cncwannabe
 

Thanks Henk. That's good to know. I was too lazy to drag the control unit away from the wall and check.

I would put the UCN5804B right at the connector because I think the circuit is at risk to be noise sensitive. I also think opto isolated step and direction signals would be required.

I was surprised how expensive the UCN5804B is on Ebay. I think I'll post a schematic of how this function can be done with discrete logic.

Best regards,
Walt

--- In Emco_cnc_users@..., "c5cnc" wrote:

Hi Walt,

The ABCD inputs of the stepper board go directly to an onboard 74LS38.
So there are no pull-up nor pull-down resistors.
Therefor a UCN5804B can be connected directly to the stepper board,
although you could consider decoupling with opto-couplers.

Kind regards,
Henk


--- In Emco_cnc_users@..., "cncwannabe" wrote:




Peter,

You should be able to find schematics in the files section of this or
the F1 group. I'll summarize what you will find.

There is a six pin connector for each axis on the F1 Stepmotor board.
They are designated X34, X35, and X36. The pin #'s and labels for each
axis are:

Pin Signal
1 5V
2 GND
3 C
4 D
5 A
6 B

The ABCD signals match the UCN5804B data sheet.

You may need to add 5V pull-up resistors to the outputs of the
UCN5804B. I don't know if the Stepmotor board provides them. Hopefully
it doesn't have pull-downs. You may also need to provide an
intermediate buffer (CMOS inverters would do) to provide some noise
margin due to the Darlington transistor outputs of the Allegro part.
You want the logic zero output to be well below 0.8V.

The EMCO system uses the "two-phase drive sequence" described in the
data sheet.

Good luck with your conversion.

Walt




--- In Emco_cnc_users@..., "keizer.peter" wrote:

Hi guys,
While searching for a cheap (an temporary) way to retrofit my F1
(and
maybe also the 5CNC) machines i found this old message here on the
beard:
"Hi
Funny, this seems to be the first post :)
A little background on my experiences.Okay, I own a F1 CNC mill for
about four years now.The native programming for the F1 is in a word
SUX.So, I look around and found the company WelSoft,its
www.welsoft.co.uk and looked at their Wellmillconversion board.
Simple
thing methinks, butgodalmighty aint they expensive!!!So, I do a
little
research on the way the wellmillconnected to the emco. Having a
circuit
diagram forthe F1 helps a lot :)
Lo and behold, I came up with a design that worksfor the past 3
years.
I use Allegro's UCN5804B chips for step/dir control,TurboCNC from
DAK
engineering for the Gcode to Step/dir translator,DeskProto for STL
to
GCODE translator andSolidworks for design.
If anyone need some help...
Gelandangan."
I have searched in google, i have read basically every message up
here
and also the EmcoF1Mill group.But i couldn't find any good
explanation
of how to do this.
It seems that it's possible to actually use the Emco stepdriver
board
and the original drivers.Then you just hook up the machine to your
pc
and use it with Mach3 or whatever and use it like that.
Is there anyone that knows how it works or can be done?
I've already ordered 3 of those chips on ebay, since they're very
cheap.I wasn't sure whether i needed 1 chip per axis, or one chip
per
machine.
I hope one of you guys can help me out!
Thanks a lot in advance!
Peter Keizer.
(I'll be posting this same question in the EmcoF1Mill group.If we
can
figure out how it works, i'll make a nice tutorial of it so others
can
do it as well.)

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