Building a Roaster PID

This blog describes the PID I put together to control the heater in the Popcorn Pumper I use to roast coffee with.  The Popcorn Pumper has been modified to seperate the fan and heater power, with a standard AC plug for each.  So, I just needed to put together a PID that I could pluf the heater power into.

I got lucky, and got a good deal on this PID, made by automation direct, on ebay
Automation direct SL4848_Series / SL4848-VR


My parts list was

SL4848-VR PID by Automation Direct
D2440-10 40A Solid State Relay, made by Crydom
Metal chassis from a local surplus electronics place
Ebay RS-485 converter
16 gauge, 3 conductor wire from Home Depot
Fuse holder from my storage box
Misc wire from my storage box
Type K thermocouple wire and female thermocouple connector from Mcmaster Carr

Here is the assembled unit.



Here is a simple schematic I made, shows how I connected everything.



I had to cut a square hole in the front of my box, to mount the PID in.


In the pic above, you can alse see the yellow thermocouple connector sticking out of the top.
I used this connector, from Mcmaster
Female, Type K mini thermocouple connector
This is compatible with the Type K thermocouples you can buy from Ebay.

I drilled a few holes in the back.
One for the fuse holder. Fuse is not shown in the schematic, but connected to the Line of the AC input plug.
Another hole is for the AC power line coming in.
Last hole is for the AC socket line, which is what the heater power from the roaster will plug into.



This is the RS-485 converter I bought from ebay.
The PID has a RS-485 output. I just connected the data-, data+ and ground wires from the converter to the PID, and plugged the convertor into the serial port of my laptop, and then I can use my laptop to control the PID.

The software required is at the very bottom of this page

http://support.automationdirect.com/demos.html

Here is a pic inside the PID, showing the back of the PID, the SSR, and the AC in and out wires.
The twisted white wires, and grey wire are the RS-485 wires, going to the converter.

Heres a pic of the thermocouple installed in the Popcorn Pumper, to measure bean temps