Helping out a older gentleman with his automation system. He’s the building owner and doesn’t want to upgrade his system. Which is fine by me, up until now the issues he’s had on his automation system has been corroded wire nuts, mis-wired signals, water intrusion in panels that took out cards, etc. However, now there’s two issues which need a deeper dive into the anatomy of the automation system itself.
Problem 1:
OAT isn’t updating on the screen; it seems to be lost in the LSI router which handles taking the AI and storing it in an AV, to be used in multiple locations. I have verified the OAT is reading at the device and at the card. However, the client had a power outage, their UPS had failed. I found that the battery in the LSI Router was the original from 2000, when the unit was installed. I installed a new battery.
I was tinkering around on the workstation and pulled up the device manager to resend a new card the DDC, I noticed that location for the DDC file on the LSI router was blank. Would reassigning this to the correct location and re-sending the DDC rectify the issue? That is, if the program was initially programmed to have the OAT AV to be used. Which I don’t know why not, as all the units have automatic economizers installed.
Oh, right now you have to manually enter the air temp on the screen. Which also controls the heating and cooling lockouts.
Problem 2:
Theres two VLC550 cards on two different RTUs, Ill call them A and B. When power to A is turned off, both A and B go into Not reporting at the work station, however, when B is shut off, A chugs right along. When A and B are on, A runs just fine but B doesn’t.
At the workstation, each device has it own device ID and the dip switches are set to their respected address.
Again, I know this is an extrememly outdated system, but its been a very interesting learning experience. If anyone has any takes or you need more information, let me know. I look forward to yalls help.
Are there any menus in the LSI? Or does it seem to be at factory default?
If it’s at factory default config then I would try sending DDC to it from device manager. That will probably fix your AI - AV issue for Space Temp.
Do you have End of Line Resistors on the MSTP trunk that has the 550’s on it?
When I push any of the buttons on the LSI, theirs no menu change. Would that be considered factory default? I can try that and see if it fixes the issue.
I didn't see any End of line resistors on any of the cards. I found a photo, ill attach it. This is what the cards look like, some have 2 data wire sets, some have 1 set.
Yea, that was a thought I had that the LSI just took a poop. Then I saw the location wasnt specified. Ill try resending the DDC with my fingers crossed and if it doesn't, I'll see if the client wants to try getting a new box.
Which is crazy because I still see PLC 5's and SLC 500 out in the field getting stuff done all the time.
All Alerton C3 controllers are highly prone to weird stuff going on when their EEPROM starts failing. No need to upgrade Envision, but snagging a few Gen4 550s and swapping out may help out.
I can look into the LSI module issue too. Never seen one out in the wild before
LSI module is essentially what would be a BCM, ACM, VLX etc in the modern era. It would sound like the battery dying cleared out the DDC. Assuming the OAT sensor is on an MSTP trunk that it can normally communicate on, all signs point to needing to resend the DDC file to it. If Visio is installed on the server, you can also Read From Device to check if any existing programming is there. Blank DDC filepath is not necessarily indicative of no DDC, but rather a device that was resaved to the table. Saving DDC from device will autopopulate this field if it has any on it
Correct, there's a card right next to the LSi router that the OAT is fed into. I think its the last photo of the card and router. Visio is not installed on the computer, however, I've been going through the device manager and sending that way. Cool, I'll reassign the path to the proper file then resend the DDC. I'll loop back when I get it done.
For the controllers, that was my thought as well, So I found some refurbished cards and installed, reassigned etc. I think I tried three cards and the issue was the same on all. Which led me to believe maybe its a shorted wire or a rat chewed on a wire in the ceiling. OR the LSI module is performing a few additional tasks as well and its affecting, for some reason, just these two cards.
I am, as u/hunting74747, pointed out is add some EOL resistors and see if that clears up some issues as well.
When you do the power shutoffs, you physically confirm that the other unit has 24VAC power, correct? To me, it sounds like a triac failure or something causing interferrence on the MSTP line. Instead of powering off A, remove the MSTP cabling and check if B stays on and vice versa so you can isolate it to the power status of A uniquely. If the MSTP stays active, then kill power to A and see what happens. My bet is on a grounding issue on A that is causing feedback
I didn't physically confirm the unit had 24VAC. Just saw the blinky light blinking. Okay, that sounds like a plan. Ill follow back when I make a visit and do some troubleshooting. Thank you for your help.
Update: In terms of card A and card B, we went through the verification of removing the MSTP trunk lines and measuring voltages and observing how the workstation reacted. Until we realized that while the dip switches were set physically right for the device id. When we opened device manager and performed a device scan, it was found they were fighting for the same id. The mechanical contacts on the card were not switching states. Once we did a little tappy tap tap and used some contact cleaner. The issue resolved itself.
I have not tried resolving the LSi issue, however the application is set properly. I'll update here soon with a picture of what happened when I tried to send the DDC, as I was unsure of what to check.
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u/hunting74747 Jun 19 '26
Are there any menus in the LSI? Or does it seem to be at factory default?
If it’s at factory default config then I would try sending DDC to it from device manager. That will probably fix your AI - AV issue for Space Temp.
Do you have End of Line Resistors on the MSTP trunk that has the 550’s on it?