Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: croy on July 31, 2011, 03:11:46 AM
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Hi to all,
I am looking to make a breakout board with full opto-isolation on Outputs and Inputs as well as 2x dedicated 10A relays.
The uses will be able to select from a further combination of;
a) 2 out of 3 comprising 1x 10A relay, Charge pump and 0-10V for Spindle control.
b) Channel Y Step and Dir or Y Step and Relay no4 (10A relay)
i believe this board will adequatly cover Lathe and Milling use.
Your comments, recommendations and interest would be most welcome.
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Hi Croy,
There are an awful lot of BoB's already available and here are just a few http://www.cnc4pc.com/Store/osc/index.php?cPath=33&osCsid=879b109464028d53cd1fc711623e996a
But - there is always room for another so good fortune with your project and I look forward to seeing the pictures of your prototype etc.
Tweakie.
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Here's another one that fits your specs pretty well. We use the 122 and love it. If you're talking about putting optos on the step/dir outputs, that's not necessary. Any drive worth buying will already have optos on the step/dir inputs.
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can you give me a ling to the site for the 122?
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Sorry...I copied it but forgot to post it....122 is on the same site...
http://www.pmdx.com/PMDX-126
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PMDX are my choice of BOB, never heard of an issue with them and the quality is very good :)
Hood
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Hi,
i nice design, but my board is a lot simpler, but ot cheep design. It was derived from my need for a low cost reliable board with the features i need for my Lathe conversion.
i estimate my board will cost less than half the cost of the 122 and still have the features i mentioned in my first post.
If people have ideas they would like to see incorporated, now is the time to speak.
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All the features of the 126 for the price of the 122 would be great. The 126 has some nice features, but the 122 does what we need it to do.
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Point taken and i may well follow up with this as a second board.
My first board is a simple discrete compoent board, I may if interest is there go down the route of a more featured design. right now I am trying to avoid coding micro-controllers or fpga's.
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For me 24v I/O capability is the way forward, maybe not such a concern for hobby type machines but for more industrial end machines its a must I would say. Then again more and more of the external controllers are having 24v I/O on them so no need for a BOB and thus maybe it will just be the lower end hobby type machines that will be using BOBs.
Hood
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If people have ideas they would like to see incorporated, now is the time to speak.
All input opto's must accept the 3.3 Volt TTL standard.
All outputs should be suitable for driving both the 3.3 Volt and 5 Volt TTL standards.
Don't put opto's on the step and direction outputs or if you do then provide a bypass connection.
That's all I can think of at present.
Tweakie.
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Hi Hood,
I designed mine because I wanted to convert a hobby Myford ML7 to CNC, and was disappointed by current low cost boards and the need to use multilpe boards.
Although i currently develop using PIC micro's, i feel these may well be insufficient for Motor control and I have not touched FPG's in 12 years, due to a career change. So you can see why i am reluctant as a first go to jump in boots and all.
However if you are willing to write down some details of what you would like to see on a basic "Industrial" board controlled by Parallel Port, I'll look into it and see how achievable it woud be with minimal change to my current design or using minimal microcontroller functionality.
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However if you are willing to write down some details of what you would like to see on a basic "Industrial" board controlled by Parallel Port, I'll look into it and see how achievable it woud be with minimal change to my current design or using minimal microcontroller functionality.
I think the point was more that in the industrial world, they are not using the PP. TCP/IP is far better and more reliable, but beyond that, most external controllers such as offerings from Hypertherm, Thermal Dynamics, Burny, etc. are stand a one controllers where everything is housed in one enclosure.
In the light industrial environment, you still find PC's and separate controllers...and the PP, but I/O is usually done with PLC's using 24VDC inputs. For that, a breakout board is still needed, but it doesn't have to be full of bells and whistles. IMO, if the PMDX-122 could accept AC input power, it would be perfect.
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Thanks Tweakie, Good point
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Well I will unlikely buy a breakout board again as I will be moving over to external control devices that have 24v I/O on any future builds I do so wouldnt want to make you change any plans. If I was doing my builds that I have at the moment which use the SmoothStepper then I would have loved a BOB that had 24v rather than 5v I/O.
Hopefully more people will see the benefits of going to 24v I/O, even on small home built machines, its just so much more noise resistant and would solve a lot of occasional issues people have.
Hood
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When you sat I/O there are two busses. the one to the PC which is 5V and the one to the machine, which n mine is 12v.
if you want the one to the machine at 24v then this is very achievable.
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Yes it would be the machine side of the BOB that would be 24v or configurable if possible. Dont know enough about electronics, in fact I know Sweet FA ;) But the drives I use can have the I/O in them set between 10 and 30v and what voltage that will be is determined by the voltage you supply to the I/O power terminals. That would definitely be a nice feature to have if possible as hopefully more will see the advantage of using the higher voltages for machine side I/O
But as said personally I will be unlikely to buy another BOB as the external controllers I, more than likely, will use in the future already have 24v I/O and dedicated 5v for Step/Dir.
Hood