PWM/frequency signal as input to Mesa card

After running some prolonged milling sessions with my mill I've decided to go a different route here.

I'm going completely replace the VFD, the gigantic 2kw AC spindle motor and the noisy 6 speed transmission.

I'll be replacing the whole setup with a Delta B3 2kw 400v AC servo rated for max 6000 RPM and use a belt drive with 1:1 ratio pulleys to drive the spindle directly.

This should give me plenty of low end torque, a built in encoder and double the max RPM of what I had before at much lower noise level.

But I just realized that the question of how to read the spindle load from the servo drive still remains. The load is available from the Delta servo drive either as an analog signal or via Modbus.

As I'm using a Mesa 7i96S + 7i84 combo I have no analog inputs available and the Modbus capable RS422/485 port is already used for the 7i84.

What's the best way around this?

Do I try to source a Mesa 7i76EU which has a few analog inputs and replace the Mesa 7i96S board?

Can I use the FPGA expansion port in some clever way without adding too many expansion cards?

 

There are 4 analog inputs on the 7I84

 

PCW wrote:

There are 4 analog inputs on the 7I84

 

PCW to the rescue!

I had no idea about how that, how could I have missed the mode setting.