The Mesa 6i25 is a FPGA based programmable I/O card for the PCI bus. This card is used to make the bridge from pc controller (Linuxcnc) to the compatible breakout expansion cards. Firmware modules are provided for hardware step generation, quadrature encoder counting, PWM generation, digital I/O, Smart Serial remote I/O, BISS, SSI, SPI, UART interfaces and more. There are currently six 6i25 compatible breakout cards available from Mesa, the 7i74 through 7i78 and 7i85:
- The 7i74 is a eight channel RS-422 interface normally used with Mesa’s Smart Serial remote I/O expansion cards.
- The 7i75 is a simple breakout/protection card that gives direct bidirectional access to all FPGA pins.
- The 7i76 is a step/dir oriented breakout with 5 axis of buffered step/dir outputs, one spindle encoder input,
one isolated 0-10V analog spindle speed plus isolated direction and enable outputs, one RS-422 expansion port,
32 isolated 5-32V inputs and 16 isolated 5-32V 300 mA outputs.
- The 7i77 is a analog servo interface with 6 encoder inputs,
6 analog +-10V outputs, one RS-422 expansion port, 32 isolated 5-32V inputs, and 16 isolated 5-32V 300 mA outputs.
- The 7i78 is a simple 4 axis buffered step/dir interface with isolated analog spindle control and spindle encoder interface plus one RS-422 port for I/O expansion.
The 6i25 supports two breakout cards so for example a 10 Axis step/dir configuration or 12 axis analog servo, or mixed configurations are possible with a single 6i25 and two Mesa breakout cards. A possible configuration is use one Mesa 6i25 with one Mesa 7i77 and through mesa 7i77 rs-422 port connect one Mesa 7i84 for expansion pins and interface with MPGs or analog inputs reading.