Wrong diagnosis

After some more instrumentation, the t-stat doesn’t seem to parse elements without content properly. The construction is ok. But isn’t. The t-stat prefers the self-closing version.
The response to a get config using the latter gets ignored and sets off.

My prior comment didn't have the tags escaped and doesn't make much sense with them missing.

The failure scenario is:

1. Set a permanent hold using the t-stat's menus
   The next post system from the t-stat will have <otmr/> in zone 1
2. Get /api/1/activity/away?clsp=50
3. The next get config will get xml that has been recycled through XMLin & XMLout. converting the <otmr/> to <otmr></otmr>
4. My t-stat ignores the xml returned by the get config, sets <cfgpgm> and maybe other stuff to 'off''. I have to go into the service menu to re-enable program mode.
   I'll look at the XML::Simple doc and see if there is a way around this.

XML::Simple doesn't seem to be able to convert empty tags to self-closing tags. In fact, it dioes the opposite.

XML::LibXML has an option $XML::LibXML::setTagCompression = 1; that represents empty elements with begin/end elements. It defaults to representing them as self-closing.

This is a bug in the XML parser in the t-stat. I don't have much hope that Carrier/Bryant are likely to fix it.

I used XML::LibXML to "cleanse" the local systems.xml response to get config. The problem is gone. Though not a solution, I'm convinced that the problem is the t-stat is only happy with empty elements as self-closing tags.

Changing libraries seems like a lot of work. Anybody have a better idea?

There's got to be a regex expression to convert to . The thermostat is really unhappy with the former.

I've worked on this for hours and all I have is a headache. This was pretty easy with SNOBOL back in the day.

The thermostat is way too picky(in non-standard ways) with xml parsing. I've been toying with the idea of only modifying the text of xml responses from the Carrier servers rather than doing correct parsing and regeneration. In throwaway test branches I've been able to convince myself that the stat actually cares about key order as well. Facepalm.

I used XML::LibXML to "cleanse" the local systems.xml response to get config. The problem is gone. Though not a solution, I'm convinced that the problem is the t-stat is only happy with empty elements as self-closing tags.

Changing libraries seems like a lot of work. Anybody have a better idea?

If it truly is the case that empty tags should always be self-closing, that's doable with an extension to XML::Simple::Minded. Possibly even with a regex on the text output, but hopefully can be done more elegantly than that.

very naive patch applied which converts cases of <tag></tag> to <tag/> Hopefully that solves your problem and doesn't blow up anything else 😄