Possibly the most convoluted smoker in the Carolinas....
After my 'Explosive Build' kept exploding, it was time for a change. $177 and Amazon.com = Commercial electric smoker, the MES 30.
Removed feet, and replaced with lockable casters. (WTF! = Where's the Feet?).
Check out that Bling
Drilled two holes in side opposite chip loader. One for smoker temperature thermocouple, the other for 'Payload' temperature thermocouple, (aimed at the second from top self, about half a pork shoulder high).
The holes are fitted with lamp tube, and their associated nuts, for a nice clean entry and exit (thanks to smf member DaveOmak for that suggestion).
Removed factory controller.
Added my own, from the explosive build....
Thermocouple signal conditioning, PID, Logic, and Solid State relay are identical to the explosive build.
List of items used...
(1) Siemens S7-1200 PLC (~ $120 requires some connections to get this price)
(2) Acromag TC Thermocouple transducers ($89 ea, List from their website - USB configurable, with free software - a pretty cool product in my opinion)
(1) 25 Amps solid state relay from Automation Direct (~ $46 list from their website)
(~) assorted terminals, DIN rail and wire ('acquired' as needed)
(1) Block of free time and a weekend to geek out :)
(1) Labview 2011 Development Software (~ $6,000 - but they have student versions :) )
(1) iPAD ($0) Your kids might already have one
(1) Android device ($0) You might already have one
(1) Wintel PC ($0) You might already have one.
Improving upon the 'explosive build' are some features (SMS text messaging) from my original terra-cotta pot build from 2010.
First step was to add ModbusTCP protocol to the Seimens PLC, (now that they now support it), so I added a Modbus TCP client sufficient to pass all the meaningful meat smoker data and commands/status to/from a modbus server.
The Modbus server is any windows PC capable of running National Instruments' run time engine. (although I used my development box and never really built an .exe for execution on wintel hardware, although I could.).
Now that the Siemens was told to speak modbus, I wrote some code on the PC to speak that as well (NI has a nice Modbus library for this).
Next up, fashion a nice GUI (graphical user interface) on the PC...
Although I could have pulled off sms text messages to my cell phone on the Siemens, it was a bit easier to figure out on the NI Labview platform...So I have some sms text text messages that are configurable at runtime (during the smoke) just in case I lapse in my oversight of the smoker....
I assume I speak to the choir here, but I found this Texas Crutch article most interesting.
Next Up, tune the PID, started a re-tuning of the PID....
Now that the data is within the NI 'ecosystem' for lack of a better word, the data can be shared via NI's network published shared variable engine....this where it gets fun....
NI provides free apps for iOS, and Android - and with just your your finger, you can configure some pretty slick looking interfaces.
Even on iOS, the analog displays are not as flexible as on the PC, see above were the analog display (or gauge) has been configured with three needles, not possible on iPAD.
On android, the app appears to be monitor only - so you cannot change the setpoint or cycle the heat from an android device.
Lastly, the web interface (from the explosive build thread)....
So all in all, that is four interfaces to the smoker....
1) Web browser (via Siemens web interface) - which can be used without all the NI stuff, and the PC just you happen to have lying around, but without bling of Data Dashboard apps.
3) Android (tablet or phone)
As my mother said " You know <son>, people have been smoking meat without need of a computer for quite some time...." to which I said....how do they fill the time?
Since re-tuning for this MES30....
It has occurred to me I need some more features.
The MES30 seems under powered, my integral gain went from ~230 to ~650, which to me indicates a very long time constant, so when I disturb the smoker (open the door to flip a brisket etc..), and thus introduce a large error between setpoint (desired smoker temp) and process variable (actual smoker temp), the reduction in P (porpotional) gain from prior builds means it takes a while for the controller to output 100% power - so i think a manual control mode would be handy, so I can command 100% power when I determine it's needed.
If I could automate chip delivery.....
Edit: Daughter would kill me to forget the adornment....
Edited by Slack - 8/3/13 at 9:56am