I’ve got an ISY-94i/IR Pro with approx. 45 devices, which has been working fine for maybe 15 years. Firmware version 4.5.4.   Been having issue the past week or so where some devices were not turning on/off at scheduled times and others would not respond in my MobiLinc Pro app or from Amazon echo through the ISY portal. It seemed syncing Mobilink with ISY would bring back some devices where I could control them, but within a few days that would no longer work and all devices were not responding. Everything appears in the console, but all devices show offline which is apparent when I restart the console and get Failed Communicating With…  each device.  Restarted ISY as well as power cycling the 2413S PLM.. Here’s a snippet of the Event log after restarting ISY:

---------------------------------

Fri 10/10/2025 08:35:03 AM : [  16 12 86 1]      ERR   1

 Fri 10/10/2025 08:35:25 AM : [  16 12 8D 1]      ERR   1

 Fri 10/10/2025 08:35:43 AM : [INST-TX-I1  ] 02 62 16 14 4D 0F 19 00

 Fri 10/10/2025 08:35:43 AM : [INST-ACK    ] 02 62 16.14.4D 0F 19 00 06          LTSREQ (LIGHT)

 Fri 10/10/2025 08:35:47 AM : [D2D EVENT   ] Event [16 14 4D 1] [ERR] [1] uom=0 prec=-1

 Fri 10/10/2025 08:35:47 AM : [  16 14 4D 1]      ERR   1

 Fri 10/10/2025 08:35:47 AM : [INST-TX-I1  ] 02 62 16 14 CC 0F 19 00

Fri 10/10/2025 08:35:47 AM : [INST-ACK    ] 02 62 16.14.CC 0F 19 00 06          LTSREQ (LIGHT)

 Fri 10/10/2025 08:35:56 AM : [INST-TX-I1  ] 02 62 16 14 CC 0F 19 00

Fri 10/10/2025 08:35:56 AM : [INST-ACK    ] 02 62 16.14.CC 0F 19 00 06          LTSREQ (LIGHT)

Fri 10/10/2025 08:36:05 AM : [INST-TX-I1  ] 02 62 16 14 CC 0F 19 00

Fri 10/10/2025 08:36:05 AM : [INST-ACK    ] 02 62 16.14.CC 0F 19 00 06          LTSREQ (LIGHT)

Fri 10/10/2025 08:36:09 AM : [D2D EVENT   ] Event [16 14 CC 1] [ERR] [1] uom=0 prec=-1

Fri 10/10/2025 08:36:09 AM : [  16 14 CC 1]      ERR   1

---------------------------------

And the error log (IP address is my PC I’m working in):

 Fri 2025/10/10 08:35:38 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53802->89 

Fri 2025/10/10 08:35:38 AM System             -170001             [HTTP:0-31]: POST[1]-->/services             

Fri 2025/10/10 08:35:38 AM System             -170001       <s:Envelope><s:Body><u:GetSystemStatus xmlns:u=        

Fri 2025/10/10 08:35:38 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53803->89 

Fri 2025/10/10 08:35:38 AM System             -170001             [HTTP:0-31]: POST[1]-->/services             

Fri 2025/10/10 08:35:38 AM System             -170001       <s:Envelope><s:Body><u:GetSystemStatus xmlns:u=        

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53804->89 

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31]: POST[1]-->/services             

Fri 2025/10/10 08:35:56 AM System             -170001       <s:Envelope><s:Body><u:GetSystemStatus xmlns:u=        

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53805->89 

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31]: POST[1]-->/services             

Fri 2025/10/10 08:35:56 AM System             -170001       <s:Envelope><s:Body><u:GetSystemStatus xmlns:u=        

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53806->89 

Fri 2025/10/10 08:35:56 AM System             -170001             [HTTP:0-31]: POST[1]-->/services             

Fri 2025/10/10 08:35:56 AM System             -170001       <s:Envelope><s:Body><u:GetSystemStatus xmlns:u=        

Fri 2025/10/10 08:35:57 AM System             -170001             [HTTP:0-31-5] 192.168.10.189:53807->89 

Fri 2025/10/10 08:35:57 AM System             -170001             [HTTP:0-31]: POST[1]-->/services          

--------

After reading a lot of posts on here, I’m thinking the issues is my PLM. I do have a new spare one that I can try, but should I go through the reset to factory default on the current one first? From what I’ve read, after reset I would select the Restore Modem ( PLM), is this correct? I do have multiple backup available if the ISY both before I started having issues.

 

Thanks,

Mark

 

    

ISY-Events-Log.v4.5.4__Fri 2025.10.10 08.58.41 AM.txt

Is the green led on your PLM lit

What is the 4 digit date code on your PLM

If you click on TOOLS | DIAGNOSTICS | PLM INFO STATUS, does it show as connected?

If you click on TOOLS | DIAGNOSTICS | SHOW PLM LINKS TABLE, what is the link count. You should run this test when the ISY is least busy

The issue most likely could be with either a failing PLM or the SD card. Don't do a reset until you narrow down the problem

 

Is the green led on your PLM lit - Yes

What is the 4 digit date code on your PLM - 1514

If you click on TOOLS | DIAGNOSTICS | PLM INFO STATUS, does it show as connected? - Yes

If you click on TOOLS | DIAGNOSTICS | SHOW PLM LINKS TABLE, what is the link count. You should run this test when the ISY is least busy - Zero

 

Your PLM is over 10 years old and most likely needs to be replaced. It lost all of its link tables.

You can try doing a restore PLM which will write the link tables stored in you ISY into the PLM.  

 

If Link count is 0:

• Go to file | Restore Modem (PLM) ... this will attempt to recreate all the links in the PLM
• Once Restore Modem (PLM) is completed, count the number of links in the PLM again using the procedure outlined above
• If the link count is still 0, then in all likelihood the PLM is dead and has to be replaced

@msteelefl

Let me know what the PLM link count is after you do a restore PLM

If you end up replacing the PLM you'll need to follow the attached procedure

Replace PLM (ISY994).pdf

Thanks for the information. I have an interesting development. I unplugged the PLM so I could get you the date code. Plugged it back in and I was hearing a repeating buzz that lasted for a few seconds off and on. I unplugged/plugged it back in and the buzzing stopped. I was looking at the console and noticed one of the devices was back on-line. I then went and queried the next active device and it came online and I was able to control the light through the console. I then repeated this for all of the enable devices, (discovered I probably could have done this by going to Network View and selecting Query) and now everything seems to be fully functional from MobiLinc and Amazon Echo. I really didn't do anything different - I had unplugged the PLM at least four times during my initial troubleshooting. 
But I still don't see anything when I go to the PLM Links Table and select Start then Count - still shows zero. What does storing storing the links on the PLM actually do in the communication process between ISY and the devices? I'm sure this is basic knowledge here, but I should know this for troubleshooting in the future.
Even though it appears to be working now, should I still perform the Restore PLM process? No downside to this? 

Appreciate your help,

Mark

Edited October 13Oct 13 by msteelefl

Attached is a PLM description from the ISY Cookbook

It appears that your PLM is failing and should probably be replaced. Unplugging the PLM several times may have brought it back to life, but that will most likely be temporary. A zero link count is not normal.

The ISY-994i Home Automation Cookbook.pdf

@Techman is right in that you are seeing signs of "the beginning of the end". I'd order, have a PLM on hand and schedule time for replacement on your terms, not when it finally stops responding

Edited October 13Oct 13 by paulbates

Do you have the older 2412S PLM? If you do is your ISY controller powered by a wall wart? The 2412S PLM had power on the cable between the PLM and controller. The presently sold 2413S PLM does not have that power. So it needs a wall wart supply if you do not have one now.

Checked the Insteon site and the 2413S is in stock. 

Edited October 13Oct 13 by Brian H

2 hours ago, msteelefl said:

What does storing storing the links on the PLM actually do in the communication process between ISY and the devices?

The PLM is really just another Insteon device.  Every Insteon device has a Links Table.  This table tells it who it will respond to, and who it can control.  When you add an Insteon device to your ISY two* links are added to the PLM Links Table (a controller and a responder link) and two links are added to the device Links Table (a controller and a responder).  Without these links, the PLM and device would simply ignore each other and your ISY would not be able to control or receive status messages from a device.

 

* It's possible more links are added depending on the type of device.  For example, a 6-button keypad will have links added for each button.

6 hours ago, msteelefl said:

Here’s a snippet of the Event log after restarting ISY

Your Event Log shows the ISY attempting to get the status of 35 devices over the course of about 13 minutes. In every case, it doesn't hear even a single peep back from those devices. During that time, it does, however, hear unprompted from two devices. Interestingly, one of the two devices it hears from is a device from which it earlier attempted to get a status update. My conclusion from this is that the PLM never actually sent the status requests. This could be a result of a hardware problem or a corrupt PLM Links Table.

3 hours ago, msteelefl said:

I then went and queried the next active device and it came online and I was able to control the light through the console.

3 hours ago, msteelefl said:

But I still don't see anything when I go to the PLM Links Table and select Start then Count - still shows zero.

These two statements should not be able to exist side-by-side. Start the Event Viewer and set it to Level 3. Then do "Tools->Diagnostics->Show PLM Links Table" followed by "Start". If you post the resulting log that may allow for more troubleshooting.

Edited October 14Oct 14 by kclenden

On 10/13/2025 at 6:37 PM, Brian H said:

Do you have the older 2412S PLM? If you do is your ISY controller powered by a wall wart? The 2412S PLM had power on the cable between the PLM and controller. The presently sold 2413S PLM does not have that power. So it needs a wall wart supply if you do not have one now.

Checked the Insteon site and the 2413S is in stock. 

No, I have the 2413S PLM. I also have a spare new one that I will be using to replace the current one with when I have the opportunity.

On 10/13/2025 at 8:05 PM, kclenden said:

Your Event Log shows the ISY attempting to get the status of 35 devices over the course of about 13 minutes. In every case, it doesn't hear even a single peep back from those devices. During that time, it does, however, hear unprompted from two devices. Interestingly, one of the two devices it hears from is a device from which it earlier attempted to get a status update. My conclusion from this is that the PLM never actually sent the status requests. This could be a result of a hardware problem or a corrupt PLM Links Table.

These two statements should not be able to exist side-by-side. Start the Event Viewer and set it to Level 3. Then do "Tools->Diagnostics->Show PLM Links Table" followed by "Start". If you post the resulting log that may allow for more troubleshooting.

From what I've learned in this thread, it does seem odd to me that the PLM still shows zero links. I performed the steps you suggested, and the event log shows two lines:
Wed 10/15/2025 06:49:10 AM : [GET-LNK-RSP ] 02 69 15
Wed 10/15/2025 06:49:10 AM : [All ] Writing 0 bytes to devices
--- ---- ----- -----
But as I stated earlier, after unplugging/plugging PLM back a few times, everything is working fine. Cleared the log and turned a dimmer off/on through the console:

Wed 10/15/2025 06:56:53 AM : [INST-TX-I1 ] 02 62 16 0E EE 0F 13 00
Wed 10/15/2025 06:56:53 AM : [INST-ACK ] 02 62 16.0E.EE 0F 13 00 06 LTOFFRR(00)
Wed 10/15/2025 06:56:53 AM : [INST-SRX ] 02 50 16.0E.EE 38.FF.B8 27 13 00 LTOFFRR(00)
Wed 10/15/2025 06:56:53 AM : [Std-Direct Ack] 16.0E.EE-->ISY/PLM Group=0, Max Hops=3, Hops Left=1
Wed 10/15/2025 06:56:54 AM : [D2D EVENT ] Event [16 E EE 1] [ST] [0] uom=0 prec=-1
Wed 10/15/2025 06:56:54 AM : [ 16 E EE 1] ST 0
Wed 10/15/2025 06:56:54 AM : [D2D-CMP 0023] STS [16 E EE 1] ST op=1 Event(val=0 uom=0 prec=-1) is Condition(val=0 uom=0 prec=-1) --> true
Wed 10/15/2025 06:56:54 AM : [D2D-CMP 0024] STS [16 E EE 1] ST op=6 Event(val=0 uom=0 prec=-1) != Condition(val=0 uom=0 prec=-1) --> false
Wed 10/15/2025 06:57:00 AM : [INST-TX-I1 ] 02 62 16 0E EE 0F 11 ED
Wed 10/15/2025 06:57:00 AM : [INST-ACK ] 02 62 16.0E.EE 0F 11 ED 06 LTONRR (ED)
Wed 10/15/2025 06:57:00 AM : [INST-SRX ] 02 50 16.0E.EE 38.FF.B8 27 11 ED LTONRR (ED)
Wed 10/15/2025 06:57:00 AM : [Std-Direct Ack] 16.0E.EE-->ISY/PLM Group=0, Max Hops=3, Hops Left=1
Wed 10/15/2025 06:57:00 AM : [D2D EVENT ] Event [16 E EE 1] [ST] [237] uom=0 prec=-1
Wed 10/15/2025 06:57:00 AM : [ 16 E EE 1] ST 237
Wed 10/15/2025 06:57:00 AM : [D2D-CMP 0023] STS [16 E EE 1] ST op=1 Event(val=237 uom=0 prec=-1) is Condition(val=0 uom=0 prec=-1) --> false
Wed 10/15/2025 06:57:00 AM : [D2D-CMP 0024] STS [16 E EE 1] ST op=6 Event(val=237 uom=0 prec=-1) != Condition(val=0 uom=0 prec=-1) --> true
Wed 10/15/2025 06:57:00 AM : [INST-SRX ] 02 50 16.0E.EE 38.FF.B8 23 11 ED LTONRR (ED)
Wed 10/15/2025 06:57:00 AM : [Std-Direct Ack] 16.0E.EE-->ISY/PLM Group=0, Max Hops=3, Hops Left=0
---- ------ -------

The modules you are controlling. Have their own link databases in them. Including the PLM's six digit id. So messages from it will be processed. Even if the PLM database is empty. Messages sent back may not be seen if the database is empty or does not have the senders ID in it.

Power cycling a few times sometimes temporarily let the PLM function again. It will not last for a long time before again stopping to function.

02 69 15 message looks like it was a 15 NAK. Either unrecognized command, end of populated database found.

I believe you thought you may have heard a cracking. In my electronics servicing. Sometime a capacitor my crackle as it pops it safety vent as the capacitor is failing. Sometimes even letting out the magic smoke.😀

Edited October 15Oct 15 by Brian H

Appreciate the info and I agree this PLM is on it's last legs as was pointed out earlier by @Techman and @paulbates .

From my notes.

Reply.txt

Edited October 15Oct 15 by Brian H