I have searched the forums a bit, and am about to make the first purchases.
Any voices of experience, or even grapevine chatter as to what works, and what to avoid, best interfaces and protocols, etc. would be greatly appreciated!
The PT100 type of thermocouple is very popular for industrial temperature measurement.
You will also need a PT100 amplifier to handle the signal from the sensor and make it easily readable. The amplifier will also likely have calibration points that you will want to set to get your +/- 1% which is a pretty tight spec at 300F.
To really get that kind of accuracy you will need to calibrate each sensor at a couple of known temperatures such as ice bath, boiling water, etc. Another approach to calibration might be a lab hot plate and a higher precision lab thermometer if you have them.
That display looks OK, but I would choose one that you know will work based on postings here in the forum. It is hard for us to know what your constraints are for the display without more details.
There are many choices for the database part as well. You should read up on webhooks in the doc since that will likely be the key to getting your data from the Particle cloud to your database.
Thanks for your thoughtful reply, BKO.
This project is for an industrial application where they are currently using Fluke meters with hi temp probes giving them the 1 degree accuracy at 300°F. I can use that to calibrate. Great info on the PT100 - thanks!
The only reason I liked that display is that it showed large text! My ideal is to be able to display the temp, and only the temp, as large as possible when the button is pushed. What displays are commonly used and easy to implement, that can display LARGE text (Is that just a software parameter)?
The database portion I’ve got! The FM in my screen name stands for FileMaker! I am a FileMaker Pro Developer, and saw the Photon showcased at the keynote at this year’s DevCon. So I know I can make that part happen! My goal is to feed the temperature readings directly into the database fields in real time during production.
I’m curious how you are going to send data directly to a database? I briefly looked into that a couple years ago and determined making an SQL connection (directly from the Photon) required to much overhead for the Photon and too much C++ development work for me (C++ is not my day-to-day language so it can be a struggle for me). So I opted to create a web-server application in .Net. All my Photon has to do is submit an HTTP request to the appropriate URL with get or post parameters and the web application does the heavy lifting of getting the data into the database. We are a Windows shop using Windows Server and SQL Server.
I have tried just about every small display type available and none are perfect--there are always trade-offs to be made. I would focus on the controller and associated libraries first.
You have to be careful to look out for zoomed in photos on displays--that display is a 0.91 inch display and around 0.5" or 12mm high. It uses the very popular SSD1306 controller so you could run the Adafruit library including the GFX library for larger fonts etc. It is an OLED display which are subject to burn-in so you will get ghost images of anything you display for a long time.
You could also get an LCD display or an eInk display. I have used Adafruit and Digole and Waveshare but there are lots of brands to choose from.
I would look for a display in the 1.2 or 1.44 inch diagonal range instead of the very small one above.
That is essentially what I plan to do, communicate with Particle’s cloud server through URLs. FileMaker now has robust capabilities to communicate with NodeJS servers, REST API’s, native JSON parsing, HTTP commands, etc.
I have seen many successful implementations, and am ready to plunge in and figure it all out!
I will be investigating whether it is best to allow the Photon to talk to its web server, which then talks to my FM Server, or if it is better (faster?) to keep communications in house on the LAN. Not sure yet if that is even possible!
Sounds like your setup is working well? Any gotchas I should know about?
Gotchas… not really. When designing for local LAN use, you have to consider security. I created a token system where the token was embedded in the device firmware and transmitted in the HTTP request. The token identified each device to the server but it could be sniffed from traffic. I’m pretty sure I was just running on HTTP not HTTPS. I was simply collecting infrared beam breaks in my store (to count walk-in traffic) so the data was not critical and who really cared if it got hacked or falsified in any way. If you can do it with a webhook, do that. It will be secured from end-to-end.
Web hook it is! This data is only temperature readings entered into fields on an iPad Pro, so it will be instantly verified, not a huge security risk. But I’m sure using Particle’s framework will be fairly straight forward (I hope!).