WiFi enabled 7day Programmable Tstat to Run PLC

I am working on a custom built energy management system that will be operated by a PLC given the scope of the project, I am looking for a run of the mill 7 day programmable thermostat that has duel outputs that can be interfaced via Wi-Fi. One of the outputs will be a dry contact that open and close as programmed for heat/cool and the 2nd output can be either and analog output that reflects the current temperature reading of the thermostat.

It seems to be an elusive animal. I can use two separate components but it would look a bit weird on the wall.

Thoughts?

First thought: You can make one. If your PLC is connected and you have an HMI, you can go with an ambient temperature sensor and automation direct has cheap PID controllers for like $40 now.

Here is a thermostat that meets yuor requirements, exactly, though. Please note that these systems tend to be very insecure and should, at least, be sitting behind a router.

https://www.honeywellhome.com/en/products/thermostat/wi-fi-7-day-programmable-thermostat-rth6580wf

The system won't have an HMI ($$$). My intention is not reinvent the wheel and use off the shelf components where possible due to cost and remotness. The EMS will work in unison with the verious systems but won't be dependent on it. Lots of uniqueness to the project.

I looked at several Honeywell Tstats. I didn't look at this one in particular but what I saw of it, it don't have a analog output to communicate with the EMS that I saw but I'll look more into it. The closet i found was the TB6980B but the analog preset the way I read it is a preset analog like foe a damper

sparkyinak said:

The system won't have an HMI ($$$). My intention is not reinvent the wheel and use off the shelf components where possible due to cost and remotness. The EMS will work in unison with the verious systems but won't be dependent on it. Lots of uniqueness to the project.

I looked at several Honeywell Tstats. I didn't look at this one in particular but what I saw of it, it don't have a analog output to communicate with the EMS that I saw but I'll look more into it. The closet i found was the TB6980B but the analog preset the way I read it is a preset analog like foe a damper

Click to expand...

You are going to need to read the data via some kind of data-link if you want to use an off-the-shelf system. Without some real $$$ are probably aren't going to find exactly what you are looking for off-the-shelf. Do post back with what you come up with, though.

I hear ya. I can find all the various needs just not all in one package. I have a couple with thyristors that I can probably use to communicate with the EMS. I just don't want to necessarily use two separate devices if I can help it. It will be awhile but I'll try and do a follow up once we proceed. Thanx for your input

My experience is that there are no residential and few, if any, commercial T-stats that have a true temperature re-transmit 'analog output' (0-5V, 4-20mA). Even in the industrial temperature controller market, re-transmit AO's are an option.

When you say that you're looking for a WiFi enabled device with an analog output of temperature, I assume that you mean you want to
- communicate from your PLC via WiFi to this WiFi t-stat
- be able to read the t-stat's indicated local temperature value via WiFi, not with a 0-5V or 4-20mA signal

I have no residential WiFi devices, but my impression is that a WiFi thermostat uses a web site or a mobile 'app' to display the t-stat plate faceimage which provides a user interface so you play with your t-stat settings and see what the local temperature is.

It is not apparent that there is factory information on extracting temperature data, as a numerical value, from either the web data view or the mobile app. I suspect that you'd have to hack a WiFi t-stat to do what you want. Those who mess with residential wifi can correct my ignorance, if that's the case. If it is a hack, then there's probably hack sites that can help you along that path.

Check these out. Second one down. Has wifi and 2 analog outputs it is fully programmable. I have been looking into these myself for my home using the modbus option. They are some of the only ones I can find that you can change the set point and other variables remotely that is still a hardwired device. I dont want any wireless stuff in my home to control important stuff, but they have that option that should work for you. If you do use these please let me know how they work out. I haven't downloaded the software yet. I'm still wating to pull the trigger on purchasing them as I need 7 of them and want to make sure they are the best option. Slim pickings for this type of device. Hope this helps.

https://temcocontrols.com/shop/tstat10-bacnet-thermostat/

controlconcepts said:

Check these out. Second one down. Has wifi and 2 analog outputs it is fully programmable. I have been looking into these myself for my home using the modbus option. They are some of the only ones I can find that you can change the set point and other variables remotely that is still a hardwired device. I dont want any wireless stuff in my home to control important stuff, but they have that option that should work for you. If you do use these please let me know how they work out. I haven't downloaded the software yet. I'm still wating to pull the trigger on purchasing them as I need 7 of them and want to make sure they are the best option. Slim pickings for this type of device. Hope this helps.

https://temcocontrols.com/shop/tstat10-bacnet-thermostat/

Click to expand...

That unit does look cool. It looks like it could be used as a nice little remote I/O as well for some slick home automation... Basic programming locally as well.

I know this isn't the lowest cost solution, but if your PLC has Ethernet this may be attractive once all is said and done. This is a web enabled thermostat that talks Modbus/TCP:

https://www.controlbyweb.com/applications/web-thermostat.html

There is a temperature sensor available that is similar looking to RTD models used in Building Automation. We've used dozens of these for environment control; you can even pick up humidity as well as outdoor temperature.

Tom

I built one of these: https://www.instructables.com/id/DS18b20-Temperature-Sensor-As-a-Thermostat/

I replaced the 3.3V regulator and the sensor for alternatives. It connects to an MQTT server running locally and I use NodeRed for the control and user interface.

I have a similar unit running as a solar powered weather station reporting temp humidity and barometric pressure.

Nick