Expanding 7i97 Smart Serial Ports using SP491 chip

ContinenteCNC wrote:

There is not much IOs connected to the second 7i84. Most of them fit in the fisrt one. 

You can use the pins on the expansion connector as GPIO (some buffering / protection would be pretty much mandatory)
Maybe consider connecting a generic parallel port breakout board. 
A parallel breakout will fix the GPIO directions, though the pins on the expansion port can be configure to be outputs or inputs. 
 

ContinenteCNC wrote:

To do so I would just need to flash the proper firmware?

Not even that, any unused functions (like stepgens etc) that are masked out by num_stepgens=4 (etc) in the HAL file become GPIO pins.

Let me ask you something.. what about the sserial port modes? I read that they set different functions to pins on 7i84 depending on the mode you load. Where do I find what each mode does? I am currently loading them on mode 0.

In the manual:
www.mesanet.com/pdf/parallel/7i84man.pdf
Page 14.

MODE 0 I/O only mode (32 bits of input data, 16 bit of output data)
MODE 1 I/O plus analog input and field voltage mode (32 bits of input data, 16 bits of
output data, 4 analog input channels (on inputs 0..3) and field voltage analog
in)
MODE 2 I/O plus analog input (32 bits of input data, 16 bits of output data, 4 analog
input channels (on inputs 0..3), and 2 MPG encoders on inputs 16..19).
Default encoder count mode is 1X to match normal 100 PPR MPGs.
Encoder input threshold is fixed at 2.5V for compatibility with 5V encoder
outputs.