PID for Smoker with dual Temp Control & Ethernet

[JeremyFXDWG]

I am looking to control an electric smoker with a PID controller. Ideally the heating element would need to be controlled to a set cooking temp with one thermocouple and the food would be monitored with another thermocouple and when reaching a desired temperature the PID would reduce and hold the temperature at a certain temp.

So basically it needs to have 2 temperature probes to control one heating element.

I would also like to have the information posted to a webpage or less ideal an email. (I really need the controller to output the data over TCP/IP. I can manipulate it to the webpage).

I saw the Honeywell UDC3200 may do this. It does email and does not appear to publish the data any other way. Any other controllers I should be looking at or is this a feasible task?

Thanks,
JP

 

[Honga]

It appears you have two different issues, firstly I don't think your system needs to know what temp the heating element is at.

If you set up one loop properly, and the enclosure is small enough to get a fast response the single temp sensor should be able to control the heating element.

Welcome to the forum!

 

[jimfun71]

So you got your smoker in the back yard and you want it to IM you when dinner is ready? LOL just kidding.

 

[JeffKiper]

there are sevral options for the user interface. I would look at a small PLC (AB 1100, AD 05, etc) and a GOOD HMI RedLion G3. You coulduse the G3 as your webpage.#Sorry for being short no time to type.

 

[JeremyFXDWG]

Honga - I agree. I don't care what the heating coil temp is I want to maintain a steady air temp in the smoker. The thermocouple will be mounted in the smoker airspace.

I want to cook at say 225* (air temp) with little temperature swing so I was thinking one loop / thermocouple / PID for that. Then when the food hits a certain temp say 190* (monitored with another thermocouple) I want the air temp to drop to 140* and hold there forever...

I am just not sure weather I need 2 PIDs or one PID with 2 inputs. Both inputs will only control one heating coil in the end.

Jim - Yep.. basically that's what I want.. .


I was looking at maybe using 2 Newton i6s?

 

[JeffKiper]

You can use 2 inputs use the first to maintain the air temp at XXX degree. Then use the other to change the PID setpoint on the first at XXX degree . 1 PID nice and easy project.

 

[TConnolly]

You need just one PID. You start with the PID setpoint at 225F, then you change the PID setpoint to 140F when the food temperature reaches 190F.

 

[JeremyFXDWG]

Excellent.. Thanks.

So one PID with 2 inputs that is Ethernet capable. Now I know what to go look for.

This is my first PID project so I appreciate the advice to my elementary questions.

 

[JeffKiper]

you wont learn if you don't ask . So do you understand what we are saying?

 

[Honga]

Your PID would run at 225 setpoint
Someting that isn't the PID detects the food temp
if it is higher than 190, change setpoint, if not leave the same.

So 1 PID 1 Input.

 

[Honga]

If you get a uLogix 1100 you could use Archies Advanced HMI and do whatever you like with the data.

 

[danw]

I want to cook at say
225* (air temp) with little temperature swing so I was thinking one loop / thermocouple / PID for that. Then when the food hits a certain temp say
190* (monitored with another thermocouple) I want the air temp to drop to 140* and hold there forever...

　
If you decide to do this with a Honeywell UDC 3200, get model
DC3200-EE-300R-210-00000-0E00 or
DC3200-EE-300R-110-00000-0E00
　
That model has two thermocouple inputs, single PID output to an electromechanical relay to drive the heater elements, an alarm relay to trip a digital input to change setpoints, ethernet (I'm not sure what the ethernet is for).
　
Set the Control group up for 2 local setpoints.
SP 1 is for air temp @ 225°F.
SP 2 is for the food-at-temp-SP2-holds-at-140°F
　
Input 1 is the air space thermocouple
Input 2 is the food temp thermocouple

Setup the control PID algorithm for time proportional. I'd start with a cycle time of 15 seconds.
　
Setup an alarm #1
- to monitor input 2 (food temp) as a source (A1S1TYPE)
- to trip on high alarm at 190°F (A1S1VAL)
- to latch

Honeywell quirk - fail safe alarms, use terminals 7 & 8 (labeled NC contacts) to get the action you want.
　
Wire the alarm output into digital input #1, terminals 10 & 11. The DI requires a sustained contact, hence the latch on alarm #1.

Set up digital input #1's function as "To 2SP".

When the food temp (on input 2) reaches 190°, its alarm will trigger, the DI will go to 2nd SP (to 140°F) from SP1 (at 225°F) and hold there.

The Run/Hold key releases (resets) the latch on the alarm once the food temp on input 2 is below 190°F minus whatever the alarm hysteresis is set at.
　
Note that the ethernet IP address CAN NOT be set from the UDC keyboard, so negotiate a sale where the vendor pre-programs an IP address for you because the alternative requires PIE software and a serial IR adapter to set the IP address. Why bother?

 

[JeremyFXDWG]

Jeff- I am beginning to understand... Dan's explanation was beyond excellent

The reason I picked the honeywell originally was that is seemed to have the 2 inputs I needed and Ethernet. The other thing was that it has a display / keyboard all built into one unit. (I didn't even know about HMIs till I was looking around this forum).

Will the Honeywell handle an SSR?