In the midst of this there is one recurring concern that I wanted to address. Many people seem to be comparing this thing to the $30 PID controllers you can get on ebay. I want to take this opportunity to highlight some of the features that set the osPID apart from the low-end competition.
More Sensor Interfaces
By default, the osPID can read either a K-Type thermocouple or a Thermistor. With more input cards on the way (RTD, Voltage, etc..) this allows you to use the osPID in more situations.
Desktop Configuration / Graphing Application
When configuring and monitoring a PID controller, having a graph in front of you is indispensable. The osPID comes with a free (and Open) java application that allows you to interact with the controller from the desktop. You’ll be hard-pressed to find this with any PID controller, and if you do it’ll cost you.
Settling on the correct P, I, and D parameters can be time consuming. Most expensive PID controllers provide an “autotune” which automatically determines good values. The osPID has this. Many cheap controllers do not.
Open Hardware / Software
If your $30 PID controller breaks, or it doesn’t do something you’d like it to, you’re stuck. The osPID is completely open. All software, hardware plans, and firmware code is freely available to download and modify. If you want it do something different, go for it! If a bug is discovered, it can be fixed and downloaded by everyone.
Initially from me, but ultimately (hopefully) from a community of people that have been there, with this specific controller.
So yes. It costs $85
What we have here isn’t an open knock-off of a $30 PID controller. The osPID has, in many cases, better functionality than even a $200 PID controller. Combine this with an unprecedented level of hackability and community, and I’d say that makes this a pretty good buy. (OF COURSE I would say that, but hopefully you agree.)