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Need a bit of help from PCW here.

I need to read two Yaskawa absolute-encoder serial position outputs into LinuxCNC — RS-422, async 9600 baud, 7 data / even parity / 1 stop, continuous (~17-byte frame every 40 ms), one per drive. So two independent, always-on UART RX lines.
  
Stack is a 7I97T with a 7I85S on P1 (running the 7i97t_7i85sd bitfile). The snag: every encoder input is a MuxedQCount (2:1 muxed), which can't carry a continuous async stream, and the only free non-muxed RS-422 receiver I can find is the unused sserial RXData1 (7I85 TB1-19/20) — RXData0 (7I97 TB4) already drives a 7I84.
  
  Can a custom bitfile place two PktUART RX on RS-422 receiver pins on this hardware? If only that one sserial RX is usable, what's the right way to get the second stream — a different daughtercard, or decode it off-board?

Thank you
EDIT: Solution plus tips:

I use Yaskawa drives. With my hardware, I ended up with a strange situation where I was one UART receiver short (I didnt want to use the Pi UART, or add any more hardware). The reading I need from Yaskawa is the absolute encoder position (needs a battery to survive power off, and an additional signal to report the servo absolute position back to mesa). Since a swivel head has 2 axis, I am one UART receiver short. However, I only need the absolute position as a single datapoint after which, the incremental position record takes over. My solution was to wire the UART via a 4pole relay so that when energized, i get UART_AAxis, ad when not energized, i get UART_CAxis. I simply reused a harmless relay. So in my case, when the chip blower is on, I read C and when its off, I read A. So with that, my 7i85 is now able to read 2 signals on 1 single UART.

I had to redo the bit file. 

The rest are standard establishing of signals.

tommylight wrote:

After you are done counting the CPU's, see lower on the right side, 16GB of swap space on a PC with 96GB of RAM memory. On laptops with 16GB of RAM i do 32GB of swap always.
Although you are correct that usually it is not needed, if you do need it and do not have it the PC will slow to a crawl.

It's not like that...
The more memory, the more Linux reserves for disk buffers, which does not mean that it needs that much, or that it actually uses that much.
With 8 GB RAM, the Linux installer creates a 1 GB swap partition, which won't help anyway.
If you really need swap space, you can use a file instead of a separate partition.
The problem is basically that modern Linux stores the existence of the swap partition in multiple places, not just in the /etc/fstab file as it used to be, which results in the system failing to boot when the swap partition is deleted...

thanx.

John had some in stock at mesaus.com

what have you guys used to interface from P1 and P2 to the switches, etc?
with the new quick turn PCB houses, I wonder if someone has already made a plug in PCB adaptor to put the same screw terminals on it?

tuxcnc wrote:

It is a good idea to manually partitioning and don't use swap partitions (Modern computers with at least few GB of RAM not need swap.)

After you are done counting the CPU's, see lower on the right side, 16GB of swap space on a PC with 96GB of RAM memory. On laptops with 16GB of RAM i do 32GB of swap always.
Although you are correct that usually it is not needed, if you do need it and do not have it the PC will slow to a crawl.

more update. i haven't posted here must because the discord forum usually helps me with understanding something claude is making up and I'd say I've gotten to the point where the machine is commissioned. half of the problems was just about electrical connections so, note to future self, don't use splices. just wait a day for a new wire to show up and spend that extra 20 bucks. 

so a 5axis retrofit is very doable, but:
(a) pay close attention to the physical properties of the machine. It's very use dependent. If you are carving foam, a direct drive or belt reduction is probably ok, and this actually makes a DIY solution for the physical build quite tenable. I think wood would be fine too if you are carving. For joinery, the precision will most certainly call for a harmonic drive (as in my use case). this means (A) weight, and ( the weight is about 300mm away from the Z axis guide. There is really no away around this. This then means that your gantry will either need to be fixed, or the there is some counterweight, or, "built like they used to be" (as in my case). I also think Z axis clearance is crucial. Have at least 18in.

That's it really. The rest is kinda sorta a load of wiring because the extra axis adds a lot of wires. Happy to take questions if there are any, but I think I'm safely migrating towards calibration, gui setup, and hopefully, making parts and prospering soon after. so glad I chose this over the other controllers

Yes, they are at assembly currently.

7i73 boards are not in stock at Mesa, so i'm just checkin if its still a viable board and will be back in stock at some point.
dont wanna spend too much time designing it in if not.
 

Yup! It may take some fiddling to get the speed you asked for to match the speed you get, but it should at least "just work"

gotcha, so I would just adjust it in LinuxCNC?

The 7i96S board has an analog spindle out which should work for that purpose - it's implemented as an isolated digital potentiometer.

Different question: if I want to control my spindle's speed, I do this through software, right? My Sherline mill's speed control uses a 0-7V range to control its speed using a potentiometer.

I have something very similar and would love to pick your brain on the ins and outs of your retrofit. I just acquired a machine myself and would like to bring this into the modern world now!

my machine was "only" a three axis machine too, but I just kept adding to it...
Mesa and Wifi should be OK; my machine has two ethernet ports. You just don't want mesa packets on the same wire as other packets.

My machine is only a 3-axis machine. I'm not sure of how much more I/O I really need. I plan on using the old Dell for LinuxCNC, so I really don't need to worry about having a free Ethernet port. Can you use a Mesa card and a WiFi card at the same time? If not, I'm fine with using the old sneakernet method.

If you're using one of the ethernet-connected Mesa cards, you'll want a dedicated ethernet port on your pc to access it - don't share it with a connection to your home router (if you're not using wifi). PnCconf is otherwise sufficient to get you going, although I think you'll eventually find yourself hand-modifying your config files to do custom things

One consideration for the Mesa cards: if you think you'll need more field I/O, you might as well pay a little extra and get a card with that built-in. I.e. 7i76EU instead of 7i96S