How to Enable Write Access to Max/Min Flow on Honeywell VAVs (VAV2101801.lnml)

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beltran

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Discussion starter · #1 · Jul 11, 2025

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Hi all,
I have a JACE integrating with Honeywell Lon VAVs (XL10s). The JACE is not a Honeywell-branded JACE, so the VAVs are using the Honeywell Lon module VAV2101801.lnml instead of the XL10Wizard module.

The flow setpoints have been proxied as read/write variables. However, the Max Flow and Min Flow setpoints appear as read-only, while Max Flow Heat and Min Flow Standby are read/write.

Looking into the VAV2101801.lnml file, I noticed that the MaxFlow and MinFlow NCIs are flagged with modifyFlag v='mfgOnly'. I’ve never attempted to edit an .lnml file before, but I’m wondering, if I remove that mfgOnly flag, would it make those setpoints writable?

<MaxFlow type='XConfigProperty'>
<scptType v='CpMaxFlow'/>
<scope v='object'/>
<select v='1'/>
<modifyFlag v='mfgOnly'/>
<length v='2'/>
<dimension v='-1'/>
<max v='65534.0'/>
<min v='0.0'/>

Has anyone had success modifying the VAV2101801.lnml file to enable write access to Max Flow and Min Flow setpoints?

Thanks in advance for any insights!

 

lwarren

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#2 · Jul 14, 2025

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Are you sure someone didn't just edit the slot flags on the actions to hide them? I don't know why you would be able to adjust the heat and standby and not those. It is possible if you had to that you could use Rapid Balance to change them. BTW there is nothing Rapid about Rapid Balance.

 

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beltran

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Discussion starter · #3 · Jul 14, 2025

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That’s what I initially thought too. The MaxFlow SCPT slot used for force-to-write actions is hidden. Either way, no luck — the SCPT is read-only and marked as manufacturer-only.

I think back in the day, when Honeywell was transitioning their product line to Niagara, I believe this was their way of protecting the product. If you weren’t using a Honeywell WEBs JACE, you didn’t have full access to everything needed to properly integrate a Honeywell VAV.

Man, you're bringing back some nightmares, what a pain that was. And don’t even get me started on exporting a CARE DB to LNS DB. At the eleventh hour, it would crash due to some invalid third-party XIF file... brutal.

 

lwarren

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#4 · Jul 15, 2025

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LOL, I use to start a synchronization at the end of the day and come back the next morning to find it failed for some reason or another. That certainly was a nightmare. The sandbox channel sure helped when you only had to make a minor change. CARE was great in my opinion, Symmetre and the LNS synchronization from CARE to Symmetre left a lot to be desired.

 

lwarren

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#5 · Jul 15, 2025

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I wonder if you can just associate it with the lnml file from the Ax wizards?

 

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beltran

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Discussion starter · #6 · Jul 16, 2025

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I tried using the Honeywell Wizard VAV2101801.lnml file. However, when I referenced the Lon XML file on the VAV, it threw the following error:

VAV2 file = 'datatypes\Vav2.lnml' – The system is unable to locate the specific file: datatypes\Vav2.lnml.

One potential solution would be to create a new module, either by using the Wizard VAV2101801.lnml or by modifying the original VAV2101801.lnml file and removing the <modifyFlag v='mfgOnly'/> entries for MaxFlow and MinFlow.

Once the new "lonHoneywelled.jar" with the modified VAV2101801.lnml file is created, it might be necessary to start from scratch by rediscovering the VAV controllers or at least one of them and recreating its proxy points.

I would love to experiment with other approaches, but due to time constraints and the uncertain success rate of making MaxFlow and MinFlow writable without major work on the existing Lon DB, I think this is better left as a wishlist item for the next project involving Honeywell VAVs.

Once again, I’ve been Honeywelled.

 

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beltran

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Discussion starter · #7 · Jul 16, 2025

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lwarren said:

LOL, I use to start a synchronization at the end of the day and come back the next morning to find it failed for some reason or another. That certainly was a nightmare. The sandbox channel sure helped when you only had to make a minor change. CARE was great in my opinion, Symmetre and the LNS synchronization from CARE to Symmetre left a lot to be desired.

Click to expand...

The issue with LNS synchronization was that CARE sent a global command setting all devices offline while the synchronization was in progress. If any problem occurred, you had to recommission all devices or manually set them online again; otherwise, the entire system would remain offline.

If you were working on an operational system, you basically had to birddog the system until the synchronization finished, or risk the system being non-operational the next day if something went wrong during the process.

CARE and XBS… super reliable