Re: [CAD_CAM_EDM_DRO] Re: Parallel port isolation
Posted by
Doug Harrison
on 2000-07-20 15:14:01 UTC
Alan;
The wonderboard project started as a plan to build an interface to make
CNCPro and other parallel port stepper programs work without having to do
any breadboarding. Just connect the dots (screw terms) and plug a DB25
cable from the board to the computer.
It started going off on a tangent as more options kept finding their way
into the scheme. Rather than continue to flog it I chose to go offline for
awhile and re-think the whole thing. The final result may not meet
everyone's needs but it is a compendium of what I gathered to be the best
combination of function vs cost. Basically:
1. Isolated limit switch inputs.
2. Solid state relays or optos (your choice) for the control outputs.
3. Your choice of optoisolated or straight through step/direction outs.
4. DB25 interface to computer.
5. On-board two channel +5V supply for input and output optos. 120/240
input.
6. Screw terms for all ins/outs. Optional DB9 step/direction outs for
modular connectivity.
7. Socketed chips.
I estimate total cost per board at $50-$80 depending on what goodies you
want. The SSR's are about $8 each. Good, high speed optoisolators for the
step/direction lines are pricey too. The options allow you to build what
you can afford. All I want is to recover most of my expenses and end up
with a good board I can use for retrofit jobs.
We now have Jon Elson committed to the layout.
Doug
The wonderboard project started as a plan to build an interface to make
CNCPro and other parallel port stepper programs work without having to do
any breadboarding. Just connect the dots (screw terms) and plug a DB25
cable from the board to the computer.
It started going off on a tangent as more options kept finding their way
into the scheme. Rather than continue to flog it I chose to go offline for
awhile and re-think the whole thing. The final result may not meet
everyone's needs but it is a compendium of what I gathered to be the best
combination of function vs cost. Basically:
1. Isolated limit switch inputs.
2. Solid state relays or optos (your choice) for the control outputs.
3. Your choice of optoisolated or straight through step/direction outs.
4. DB25 interface to computer.
5. On-board two channel +5V supply for input and output optos. 120/240
input.
6. Screw terms for all ins/outs. Optional DB9 step/direction outs for
modular connectivity.
7. Socketed chips.
I estimate total cost per board at $50-$80 depending on what goodies you
want. The SSR's are about $8 each. Good, high speed optoisolators for the
step/direction lines are pricey too. The options allow you to build what
you can afford. All I want is to recover most of my expenses and end up
with a good board I can use for retrofit jobs.
We now have Jon Elson committed to the layout.
Doug