This thread explains how to use a Raspberry PI (could be a zero or an A) to bridge between the ISY and the USB 2448A7 if Polisy is not available to you for whatever reason.  I looked into using a RP2040 based board (Pico, $4)  but none of the software packages (C, micropython, circuit python) currently support host mode USB beyond HID class devices. 

https://forum.universal-devices.com/topic/32546-insteon-2448a7-raspberrypi-isy994/

 

I have a couple of PLMs that are dead.  I've tried fixing the last one with some cap replacements; went from no lights to a green light, but the ISY doesn't see it still.  Not sure what I did wrong...

I plan to send the other to a repair guy on EBay, maybe I'll get one that works.

Trying to hedge all my bets, I also bought a Polisy from UDI store, no idea when that'll arrive.  I forgot how much I'd miss having a working ISY.

Serial port board may have a problem. I have seen a few reports by Smarthome they also has some issues with the serial chip. Revision 2.3 has a new chip and 2.4 a whole updated serial bard.

Maybe you got the board plugged in with a bent pin or damaged a plated through hole mounting one of the capacitors. So both sides of the board are missing a connection.

Went back and reviewed my work today, and found I'd missed a couple of capacitors.  Redid the work and verified the serial board was seated properly.  And it worked!

I'd gotten the replacement parts from someone on EBay that sold a recapping kit.  Followed the instruction here and seems to be good.  Thanks to all here for posting all this info, especially now when replacements are so scarce.

For 2 or 3 weeks now I have been seeing a similar problem; "Can't communicate with..." insteon devices, sometimes all of them. A power cycle (meaning unplug isy & plm, then plug in plm then isy) temporarily fixes the problem (often with a need to 'Write updates' to some devices). 

So 5 days ago I did the cap replacement, but that didn't fix it. It still works for a few hours, and one time 2 days, but usually by next morning the same thing (can't communicate). My plm is 2413S rev 2.4. 

16 hours ago, tomho said:

(often with a need to 'Write updates' to some devices). 

are these battery powered devices?  Are you satisfying the need, meaning are you clearing all the need to write devices?  are there any green 1101 icons on your device tree?

Do you have pro or standard?  If you don't know, do you have these two buttons on your admin console ribbon? 

If there are "write updates" what happans is anytime the PLM tries to communicate it tries those devices too.  Which leads to alot of power line congestion and errors.  If these are battery devices you can temp fix by pressing the right button shown above (the one that looks like a battery) which will disable battery device writes.  But then you need to get rid of all those 1101 icons on the device tree.  To do that put the battery device into set up mode then right click it in the device tree and pick write updates.   (this works much better if you have "pro" and can press the button discussed above before you start.)

It's the standard isy, and the two 6 button keypads are the ones that need to write updates, and yes they show the green icon. I'm not to concerned about that, I just do the writes. 

However, I might have figured out something else as to why the "PLM" stops communicating some time after the power cycle. 

When I logged onto the admin console I used the event viewer to see what is trying to talk. Twice, maybe 3 times, during those 2 or 3 weeks I have had this issue, I have had a continuous flood of "X10 Status Request" events. It didn't happen every time, so I didn't think much about it. Yesterday it came up again so I tracked down what appears to be causing those. I still had an old Radio Shack plug'n power Remote Controller (shows my age, does anybody even remember Radio Shack?) plugged in to occasionally command some X10 devices. Anyway, unplugging that thing stopped the Status Requests, and so far (fingers still crossed) the PLM failures. 

I'm guessing here, but perhaps the constant X10 requests some how overloaded or confused the PLM and it just gave up until a reboot cleared it. I'm assuming the X10 thing is random and I don't know what starts it. I do have some X10 devices under ISY control, but those are very rarely used. Anyway, time will tell. 

I remember Radio Shack modules. I still have earlier Insteon modules that could have an X10 address added to them and I still use an X10 16 address palm pad to control them. Though the ISY994i does not follow the changes.

It does sound like the controller has issues.