I have a backup ISY 994i controller which did not have a SD card in it. I purchased a new 32GB PNY micro SD card and formatted it to FAT32 format per the documentation available. After inserting the card and starting up the ISY, the indicator lights seem to reflect the state of the controller correctly. So I attempted to start the Admin Console for this controller. The Admin Console would not come up.

I connected to the ISY via Telnet. From the ISY shell, I formatted the SD card using the FS command. Not sure if you're supposed to get the shell prompt back after formatting it. The session timed out. I assume the formatting was complete and try starting the Admin Console again, but nothing came up. I swapped the SD card from another ISY not in use and the Admin Console started up just fine with it. So I'm assuming the issue has something to do with the SD card.

Can anyone provide me with any guidance on this? Formatting the card from Disk Utility on a Mac with a FAT32 partition didn't generate any errors.

@matapan I'm assuming by "per documentation available" you were following the instructions found in the wiki:

https://wiki.universal-devices.com/ISY-99i/ISY-26_INSTEON:Replacing/Formatting_an_SD_Card

It says if it was a new SD card you wouldn't need to format it. I'm not sure if formatting it has any impact on the NEW card or not, but perhaps some artifacts from macOS formatting it might happen (not familiar with macOS to know if even doing FAT32 doesn't add some "mac cooties" to the sd card.

According to these directions there should be a "Goodbye" message after the formatting in the telnet session and then the ISY should reboot. I think at that point you have a very basic way to access the ISY994 via the admin console and that's why/where you would then need to update firmware to the latest for that specific device.

NOTE: do you have a PLM connected to this "backup" ISY994? If not, you should only download/install the non-Insteon firmware. Otherwise, without a PLM connected you will always launch into admin console in "safe mode".

I wonder if you could disk copy the working SD card to the new SD card and try that to see if it would boot up. I've never attempted it, so just a swag suggestion.

Otherwise, try the telnet formatting again. Is there a way you can wipe the new card of any information and put it in an unformatted state?

Did you follow step 3 and start the program to add the firmware to the ISY994i? As the SD card does not have the needed firmware in it to be successfully started normally. Then you pick the backup you want to use in it. The telnet format was supposed to get you a slightly better performance. I too had it look like it didn't give the last expected ending but seem ed to work fine.

1 hour ago, Brian H said:

Did you follow step 3 and start the program to add the firmware to the ISY994i? As the SD card does not have the needed firmware in it to be successfully started normally. Then you pick the backup you want to use in it. The telnet format was supposed to get you a slightly better performance. I too had it look like it didn't give the last expected ending but seem ed to work fine.

I did not follow step 3 because I was unable to launch the Admin Console with the formatted card installed. Is it possible to install the card after the Admin Console boots? I think the Admin Console came up without the SD card installed.

In the ISY994i. Only a small loader is in the processor on the board. Most of the remaining operating system is on the SD card now formatted but with out needed firmware. The link in the SD card replacement. Gets you access the ISY994i Administrative Console. You then have to use a backup to add the rest of the needed firmware, and others like your stored programs etc.

I am not sure the ISY would handle a card larger than 16MB. It could only use a max 2MB of partition size as it used the old standards.

Only format the SD card inside ISY to be sure. It should be automatic from there. IIRC it was FAT.

Try a smaller SD card size if you have an older one laying around. ISY originally came with a 2BG SD card.

The max size for the SD Card for the ISY is 32mb

Formatting the SD card in the ISY seems to hang the shell. I never get an OK response when it's done. I can format the card in MacOS disk utility as a FAT32 partition. Can the SD card be inserted after the ISY boots and the Admin Console is brought up?

3 hours ago, matapan said:

Can the SD card be inserted after the ISY boots and the Admin Console is brought up?

Unsure. And since nobody answered the first time you asked either they didn't see the question or don't know either. Try it and let us know.

Strange that formatting in the ISY is causing the telnet to hang. Do you happen to have a different computer to test with? Wondering if a Windows connection would be different.

Doubtful, but could be a bad SD card. Do you have a "spare" that can be wiped and tested to see if the PNY card is bad? Probably not likely to have many 32GB micro SD cards laying around.

Since this is a "spare"/backup ISY994 do you know if this ever worked? Did you recently buy this device or is it one you've had and just haven't been using?

I would not remove or insert an SD Card with the powered on ISY994i. Asking for damage and most of the ISY994i firmware is on the SD card.

On 1/24/2026 at 10:06 AM, Techman said:

The max size for the SD Card for the ISY is 32mb

Strange. With FAT = FAT16 there was only 2^16 sectors (65536) at 256bytes each = 16MB

Was there different releases of the ISY hardware that could address larger sectors? Storage technology did change very fast back then. Did ISY hardware become FAT12 or FAT32?

IIRC there was also some 2MB restriction (ISY was supplied with 2MB SD cards) there also and if you didn't partition the SD card at 2MB it could eventually overflow the 2MB limit and crash the system without any warning.

1 hour ago, larryllix said:

Did ISY hardware become FAT12 or FAT32?

In the link I provided above looks like ISY994 could use either FAT 16 or 32.

Also there is this comment:

• Please note: ISY supports up to a 16GB SD card with 4.2.18 firmware and above, any firmware before this only supports a 512MB SD card

Later on it seems there is the ability to go up to 32GB card. I think can use a larger, but ISY994 would only recognize/use 32GB. I’m not sure as I never tried bigger cards. Only replaced my card once (I think for testing purposes) ages ago.

I think I'll try a smaller size card and see if this works

I was able to use the original 32GB card.

Here is the executive summary: Use a Windows PC to format the SD card and to copy the firmware files to the card. If you are a Mac user, you may experience the same problems I did if you decide to go the route of using MacOS disk utility. For whatever reason, the ISY will not read the card and report an error by flashing its red error light.

Read further if you want some details.

I first tried formatting the 32GB SD card in MacOS Disk Utility in FAT32 format. I subsequently copied the firmware files to the SD card, ejected it and installed the card in the ISY. This resulted in the controller starting up and reporting an error.

Next, I tried formatting the card in the ISY itself from the ISY shell. The format operation curiously did not complete with the expected completion message. I was reluctant to try copying the files and trying to boot with the card.

I then ordered a 16GB SD card, formatted it in Disk Utility, then copied the files to the card and tried it out in the controller. No joy. Same error. Since I had access to another SD card from which the controller would boot successfully, I tried cloning the card using Disk Utility, creating a dmg file from the known good 4GB SD card and writing the image on to the 16 GB card. Again the ISY complained about the cloned card as well. I tried Balena Etcher to write the card from the image created again to see if that made any difference. It didn't.

So I tried making a bit for bit copy of the working card to an image file using the dd utility, then I tried the cloned SD card in the ISY. Same error.

I was out of ideas other than what Geddy suggested. So I tried formatting the 32GB SD card on a Windows laptop, copied the files to the card and tried this out. This worked.

I don't know what the subtle differences are in the FAT32 formats on Windows and Mac, but I think there is one. If anyone is going to try a bit for bit copy of a card, try using the same size card.

Just take the easiest route and find a Windows machine. You will save yourself a lot of time and headaches.

Glad you got it working. The information may assist someone with similar issues.