Which Mesa combination should I choose?

I have a simple gantry router similar to the Openbuilds LEAD machine. Linuxcnc drives the steppers through a CNC4pc C50R1 bob which also has the E-stop and probe connections. The prox and limit switches are connected through a C10 bob. All axes are driven by lead screws at 2540 pulses per inch. The maximum frequency for any axis is about 8800Hz. Currently there are 9 inputs and 1 output not counting the steppers. I will probably add another output to control the router at some point. The router speed is controlled by an ESP8266 inspired by the Super-PID connected to a KBIC125.

Linuxcnc currently runs on a Gigabyte GA-E350N-WIN but I just got a HP 8300 with an i5-3570 as a replacement. Both PCs have a realtime latency of about 20us or less. While I haven't tested the Preempt latency for a long period the 8300 was less than 100us. Given the apparent direction of the Linuxcnc software it seems like this might be an opportune time to move away from the parallel port connection. This PC gets as much use as a general purpose PC in my garage as it does running Linuxcnc and Wheezy is a problem for some other software. The desire to move away from the parallel port is driven by software direction rather than a performance improvement. Any improvement in machine performance would certainly be welcome but not expected.

With so many options in the Mesa line I am a little confused as to the “best” choice. I have read through a bunch of other posts but none gave me the confidence to place an order. It seems the 7i76e/7i96e are currently very popular and either would accommodate current and future I/O needs. The 7i92 seems like it might be easier if it can connect to my existing bobs. However, any future expansion might be more difficult. I haven’t really explored other options within the Mesa line.

All suggestions are welcome.

John

I'm far from a pro, but i'll go with the 7i96, and it has expansion ports
Esay to setup, lots of in/out ports, a couple of encoder inputs a well

It seems the 7i76e/7i96e are currently very popular and either would accommodate current and future I/O needs. The 7i92 seems like it might be easier if it can connect to my existing bobs. However,

The 7i96 or 7i92 does not have the spindle control 0-10V or spindle encoder like the 7i76e but if you don't need that then the 7i96 is a nice choice

There is also the option of getting a 7i92 now and leave everything as is, you can get much higher step rates so more microstepping and much quieter machine movement, later you can add a 7i76 and have plenty of IO and full spindle control. If you go this route, get the 7i92M as it just plugs into 7i76 removing the need for a D25 cable.

I think with a spindle if you have the budget, just go to the 7i76e (or 5i25/5i26 plus 7i76). 32 inputs and 16 outputs plus heaps of extras.

The ethernet cards require PREEMPT_RT kernal.

All of them & quickly, time is running out for "He who dies with the most toys wins"

7i92 & 7i76. or 7i76e.

Some of the reasoning I went with Ethernet.
1. Easier to swap out a failing computer, even if the MB is in the control cabinet a backup can be patched in by just swapping an Ethernet cable.
2. Who knows when PCIe ports are going to be dropped from consumer pcs and reasonably priced MBs, what I call futrue proof insurance.
3. A good range of SBCs can be used, some of the better ones have a non-usb Ethernet connection.
4. If for whatever reason you have your PC further away from the main controller connection is easier with an Ethernet cable.
5. RTAI & The Evil That Is UEFI, don't play nicely at the moment. RT_PREEMPT can be used with UEFI firmwares.....I don't want to refer to it as a BIOS.

These are just my opinions, apart from UEFI being evil, that is gospel