Responses mixed with quotes below:
>>My personal feeling coming from the PLC world is solid state outputs
to 24vdc sinking or sourcing
Solid state outputs are going to be available. The choice that we are
left with is to also offer a relay version.
The solid state outputs will be capable of operating as sourcing or sinking,
with an interface voltage range from 5 volts DC to 25 volts DC.
Another choice is how important it is to choose sourcing/sinking for a bank of
outputs, or to allow individual selection. The latter requires more connectors.
>>Can you make the inputs volt range from 5-30 or so, to cover a 24v system?
As stated above, the sourcing and sinking outputs will have a normal operating
range of as low as 5 volts and high as 24 volts nominal.
>>I personally like this one (relays) the best, it give the MOST flexibility.
We will try to offer relays as an optional configuration.
>>Can't you just run a an opto-isolator IC chip for each block of 8,
>>and have those IC's in a IC socket so if you blow one, you can just
>>order a replacement chip that the user can just swap it out.
The reasonably priced driver chips that can handle both sink or source up to
24 volts come in surface mount packages. Also, sockets introduce reliability
and cost issues.
>>I think you should have isolation on both the input and output side.
That is a given.
>>Opto22 is EXPENSIVE and not a lot of bang for the buck.
Support for Opto 22 would likely be a different board. We expect it to be used
mainly for retrofits where the Opto 22 racks and modules are already in the machine.
>>PLEASE offer an "Adapter" or "Mounting" system in where we can mount
>>Your smart bob, and your other products on to a DIN rail system!
DIN rail trays will be offered for the expansion board as well as for the PMDX-426
that it is designed to work with.
>>Trying to create a pendant or more complex IO has been a challenge.
The board being considered is for industrial I/O and is probably not a good fit for
a human interface device like a pendant. If an off the self pendant is not acceptable
to you, then a device like the PoKeys model 57 would offer more (non-isolated) I/O
for the price. Pendants should not need isolation and 24 volt capability. Mach4 can
readily run a mixture of devices and plugins at the same time, so long as only one
of them provides axis motion outputs.
>>I'm leaning towards a sink/source output board with inductive load protections on board.
We are hoping to use a driver that can handle up to 50 milliJoules of kick back
energy internally and may add external clamp diodes if we can be sure that they
do not otherwise degrade the performance.
>>.... to avoid confusion about usage...
The expansion board that we are discussing is a slave device to a PMDX-426 or
other PMDX controller board. It does not talk directly to the host computer.
>>.... on being all things to all people...
We are not expecting much in the way of sales volume for a product like this and
trying to cover all bases will just make it more expensive and less likely to sell.
Our goal is to provide a good basic set of features and let people with special
needs pursue add-ons from more specialized vendors.
>>.... why 24 I/O points...
Because that is a popular size interface chip to the serial bus used to talk to
the processor on the card hosting the expander board. If more I/O is needed, it
will be possible to use multiple expansion boards.
The feedback that we have received is much appreciated.
Steve Stallings
www.PMDX.com