Mesa 5i20 daughter cards

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16 May 2010 20:49 #2878 by Rick G
Hello all,

We are just about done with the mechanical work of converting our newest knee mill to EMC.
It is now time to decide on electronics. Although the parallel port has been fine on the machines we have done in the past we are now looking for a smoother, higher step rate and more inputs. Our stepper drivers can handle up to 2Mhz max pulse rate.
Besides the home and limit switches we would like to have extra inputs for spindle rpm, set up for rigid tapping etc. We are not using encoders for the stepper motors.
Our machine is set up for XYZAW and a VFD for the spindle. The Mesa 5i20, 5i22, 5i23 look like great candidates and there has been a good discussion on their differences and merits. The big question now is what daughter card to use with EMC?
The 7i47 looks good but are the inputs dedicated to encoders only?
The 7i47S is similar but with an analog out for the VFD and only lacks the two relays we need to control the VFD on/off and direction.
7i42TA Breakout/FPGA protection card?

What combinations, experiences have you had in the past?

Rick G

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16 May 2010 23:09 #2879 by BigJohnT
Rick,

The 5i20 is all you need for EMC unless you need the extra plug on the 5i22. I used 7i37ta isolated I/O cards on my Hardinge conversion as all my I/O is 24vdc... you need to pay attention to that as some cards are only 12vdc and some are ttl only etc. just depends on what you need. On my plasma cutter I went direct from the 5i20 to my Gecko 203v drives but used 7i37 for I/O...

John

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17 May 2010 16:23 #2885 by andypugh
Rick G wrote:

Hello all,
We are just about done with the mechanical work of converting our newest knee mill to EMC.
It is now time to decide on electronics. Although the parallel port has been fine on the machines we have done in the past we are now looking for a smoother, higher step rate and more inputs.


The 7i43 is possibly worth a look too, it connects to the P-Port and gives you the fast hardware stepgens and encoder counters up to a total of 48 IO lines. It might make wiring easier in some situations. (It is what I use on my mill/lathe combo.) Functionally it is equivalent to the PCI cards, apart from having fewer IO lines (the PCI cards have 72 or 96 pins) and then there is the external PCIE 3x20 card with 144 pins. I don't know how well EMC2 works with the 3x20, but the driver certainly knows it exists.

You might not need any daughter cards at all, the various stepgen etc outputs are available as logic levels on the FPGA card connectors. The daughter cards are mainly various types of signal conditioning.
My 7i43 plugs in to a section of stripboard with pin headers on it for each line. Some are wired to buffer ICs to drive relays, but many of them wire straight to encoders and limit switches.

There are a range of different firmwares available for each Mesa card with various combinations of modules, but you get a choice of how many of each you initialize and any unused pins are available as general purpose IO. I am not sure whether unused pins are easily usable with daughter-cards fitted, but there is no reason you can't fit two output connectors to the ribbon cable and only have a subset of the lines crimped into each.

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19 May 2010 11:07 #2905 by Rick G
Replied by Rick G on topic Re:Mesa 5i20 daughter cards
Hello John and Andy,

Thank you for your replies and the excellent information. I am looking at the 7I47S primarily because it has the analog output to control a VFD for the spindle. It turns out that the inputs on the 7I47 are differential and designed for encoders and as Peter pointed out to me it would be "awkward" to use them as home and limit switch inputs. As you have pointed out the outputs of the 5I2x can go directly to the stepper drivers and limit switches and their use can be programmed. I was however looking for a neat and simple way to convert from the ribbon cable to external wiring. I am looking at the 5I2x with the thought that it and the daughter card and MB will all be in the same enclosure without the bulk of a parallel cable. The stepper drives will be external. I will look into this more and keep you posted.

Thanks again,

Rick G

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19 May 2010 11:24 #2908 by BigJohnT
I made a little breakout board from a radio shack perf board and a plug from newark



John

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19 May 2010 13:19 #2912 by andypugh
PWM to voltage only needs a resistor and a capacitor in its simplest incarnation. You can probably do it by mounting the components on the VFD terminal clamps (not that I am actually advocating that)

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20 May 2010 10:29 #2920 by Rick G
Replied by Rick G on topic Re:Mesa 5i20 daughter cards
John that looks like a neat solution for signals that do not need any conditioning, do you have the part numbers?
My stepper drivers are optoisolated and my limit switches can be 5 volts so in theory they can be wired right to the board.
As far as the VFD is concerned it seems to me to make sense to have some protection built in.

Thanks guys,

Rick G

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20 May 2010 11:04 #2923 by andypugh
My "Breakout" is effectively identical.
I mounted a ULN2008 to the board to drive the FWD/REV button contacts on the VFD
The PWM was a little more complex as I needed a fully isolated 0-10V for a speed controller where the reference was the +100V line....
I ended up with an isolated 5V-12V DC-DC converter and an opto-isolated PWM-Voltage converter.

I have a schematic somewhere, but it turns out that I messed up the design and the PWM-voltage conversion is badly non-linear unless the PWM frequency is around 300Hz. If you are happy with a 300Hz PWM then I can forward the schematic.

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20 May 2010 11:07 #2924 by BigJohnT
The header part number is HRP50H-ND and I got them from Digi-Key
A terminal block that has the same pin spacing is A98074-ND and A98336-ND
I got the board from radio shack and don't know the part number.

The 7i24TA card for $45 from Mesa might be worth the hassle of making something. I might not have made them if I knew about the 7i42TA before hand.

John

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21 May 2010 11:03 #2947 by Rick G
Replied by Rick G on topic Re:Mesa 5i20 daughter cards
O.K. it all makes more sense now. Mesa offers a great deal of choices, so much so that it can become confusing to the hobby user. If we base our selection on a 5i2x or a 7i43 we just need to nail down what our input/output needs are.
We can build a breakout board with a minimum of components and cost for general purpose I/O and even spindle speed control.
Mesa offers several attractively priced daughter cards to mix and match depending on what we need.
7i47S step motor control, encoders, spindle control and analog out.
7i37TA isolated I/O 24V limit switch and outputs
7i42TA breakout board with protection for general purpose I/O

I assume all of these work fine with EMC.

Have or can either of you posted your set up files?

Thanks again,

Rick G

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