Best way to "Trigger" my Elk System

Since Elk doesn't support 1wire temperature monitoring i just got a web control board where I will monitor a few temperatures (fridge/freezer/etc).
 
When they go above a certain condition I was going to send a signal to my Elk system.  This way I can use the elk speakers to say something, beep keypads, email (using SSL), etc.
 
What is the best way to wire up a web control output to an Elk input?
 

A very good question.  It seems ELK does not have open communication protocol like ISY for 3rd party devices to communicate with it over HTTP port.  If someone knows how to communicate with it, we would work out something to support that.

I was thinking of something simple like a pull-up resistor or a relay. It would at least allow me to know a temperature is in an alert condition. I could then check the webcontrol to see which temperature is out of range and by how much.

But I would love more integration and not having to wire up multiple relays to he Elk input board!

You probably don't need relay board, just alarm panel input directly wires through a 10K resistor to WC8 TTL output, if all you wants to know is the level.

You can write a little PLC program on the web GUI, in that you can specify at what temperature to turn on a TTL output, when to turn it off.  If your ELK has more than one inputs can be used, you can program more TTL output to do certain things you planned on ELK. WC8 can also send email by itself, although it requires the email server taking plain email (non-SSL).

Does the CAI board have an analog output?

It does not, but by adding a D2A module on its I2C bus, it can generate analog output. connects to WC8 I2C terminal:
 

http://www.ebay.com/itm/MCP4725-12-Bit-2-7V-5-5V-I2C-DAC-Module-Development-Board-for-Arduino-/201538541467

Using this little PLC program to generate analog output
 

don't know if that answered your question or not.

Although most DAC chip module is max 5.5V output, it can be amplified using a low cost op amp to get 10V range for controlling purpose.
you can look how TI did that by using a buck op amp:

http://www.ti.com/lit/df/tidr223/tidr223.pdf

simply replace the first stage DAC by above mentioned I2C DAC module.