Step/Dir or Analog?

vre wrote:

Can i use 5i25 alone without 7i76 or 7i77 ?
Can i use my own custom breakout board with 5i25 ?

Yes, you can.
I use a 7i77 for the analog I/O and 6 encoders, and the second port for another encoder and stepgens.

But keep in mind that the 7i76/7i77 hardware is very well built. It would be hard to duplicate the same level of robustness and realise a significant cost saving.

I have seen that 5i25 sold with 7i76 or 7i77 firmware preloaded ... exists firmware that can i use it with my custom made breakout board ?

Yes, there are many firmwares available. Download the 5i25 support software and see if there is an existing configuration that suits you. For steppers that would be the 2x7i76 firmware; gives you up to 10 stepgens and the unused stepgen pins are available as general purpose I/O.

Daughter boards 7i76/7 have more I/O than 34 which have 5i25.. is this done with multiplexing ?

The I/O runs over a serial interface so it consumes only 2 5i25 I/O pins.

can i compile vhdl firmware sources if exist in xilinx ise and synthesize the fpga again without the 7i76/7 option ?

Yes, you can.

Also 5i25 can output 500khz step/dir and read 500khz quadrature encoders (10000ppr(4 x 2500)@3000rpm) alone without daughter cards?

Yes.

Ok then i will buy 2pcs 5i25 to have total 68 I/O in parallel not serial
i want I/O
2pcs servos x 2 pins for step-dir + 3 pins for encoder ABZ + 4 pins for servo general inputs + 4 pins for servo general outputs = 26 pins
4 pins for lathe ZX stop limits
3 pins for spindle encoder ABZ + 1 pins for spindle pwm
total 34 I/O pins for basic fuctions of lathe

For misc lathe functions such as tool changer, MPGs, cooling fluid, lights etc i will use another 5i25 or the parallel port.

Also i will use some AM26LS32 (quadruple differential line receivers), AM26LS31(quadruple differential line transmitters)
and some 6N137 high speed optocouplers and a rc low pass filter with op-amps to convert pwm spindle signal to analog 0+10v for spindle vfd

I have checked my servo (made in china) analog interface and found a strange problem...
Without any voltage applied (+-10V) motor rotates with 1-2 rpm and from menu display i see a voltage 0.01V 0.02V between Vref and AGND (analog interface pins).
I have shorted these 2 pins and this voltage does not disappear. Maybe is some noise from power line because i don't have any low pass filters or isolation transformer.
So to avoid this problem i will go with step/dir driving which has immunity.
In mesa store i see 2 versions of 5i24, 5i24-16 and 5i24-25 (20$ more) which version to buy ?
Also i have checked the existing configurations for 5i24 and i don't found 1 which fits 100% to my case.
Is possible to resynthesize the fpga with exactly modules i want ? (3 step/dir generators, 4 quadrature encoder readers, 1 pwm and all the rest pins general i/o ) .
To reprogram fpga i must change first the vhdl code for this specific configuration i want because this configuration doesn't exist ready in source.
Is this task easy if you don't know vhdl (i know software programming/not hardware) ?
Also i see that 5i24 doesn't supported in 2.5.X but supported in 2.6pre4 is 2.6pre4 a "working" version ?
(sorry for these strange questions but iam totally new to cnc)

vre wrote:

I have checked my servo (made in china) analog interface and found a strange problem...
Without any voltage applied (+-10V) motor rotates with 1-2 rpm and from menu display i see a voltage 0.01V 0.02V between Vref and AGND (analog interface pins).
I have shorted these 2 pins and this voltage does not disappear. Maybe is some noise from power line because i don't have any low pass filters or isolation transformer.

That's just an inaccuracy in the drives' measurement electronics. In my drives there is an 'offset' parameter to tune that, but it would be just as easy to enter a 'bias' value in the LinuxCNC PID settings.
Also, the I-term of the PID will zero out these small errors.

Is possible to resynthesize the fpga with exactly modules i want ? (3 step/dir generators, 4 quadrature encoder readers, 1 pwm and all the rest pins general i/o ) .

Yes: www.linuxcnc.org/index.php/english/forum...-both?start=10#45484

To reprogram fpga i must change first the vhdl code for this specific configuration i want because this configuration doesn't exist ready in source.
Is this task easy if you don't know vhdl (i know software programming/not hardware) ?

If all you want to do is change the configuration to a different subset of modules, it it fairly easy.

Also i see that 5i24 doesn't supported in 2.5.X but supported in 2.6pre4 is 2.6pre4 a "working" version ?
(sorry for these strange questions but iam totally new to cnc)

I am running 2.7.0~pre without serious issues.

I have checked the servo manual and found 2 functions for auto and manual compensation of this voltage.
I ran the automatic function and problem disappeared.No more rotation without voltage and Vref - AGND = 0.00V now .

In 5i24 firmware modules for stepgens, quadrature encoder readers, pwm, general i/o the signals are multiplexed or all signals are discrete ?
Because iam planning to use alone the 5i24 with optoisolation only and if the signals are multiplexed i will can not use it alone.
Also how many gates have the 5i24 x16 and how many the 5i24 x25 ?

Whether signals are multiplexed,serial or discrete depends entirely on the configuration
some configurations use multiplexed signals or serial communication on the FPGA I/O to reduce pin usage but this depends on the configuration. Many standard configurations dont use any multiplexing

Xilinx no longer specifies gate equivalents but a XC6LX16 is probably close to 800K using their old "gate" numbers. (much larger than needed for normal Linuxcnc I/O applcations)