DIY roaster problem - Arduino Uno

[bionut00]

Hi everyone,

I'm a coffee enthusiast building a DIY roaster and I'm hoping someone can help me figure out what I'm doing wrong with my Artisan setup. I'm not a programmer, I found an Arduino sketch online and adapted it as best I could, so please bear with me!

My Setup:

• Bread machine (used only as a mixing vessel with the agitator - heating element disconnected)
• 2000W hot air gun as the heat source
• Arduino Uno as the controller
• 2x MAX6675 thermocouples (one for air temperature / ET, one for bean temperature / BT)
• 40A Solid State Relay (SSR) to control the hot air gun
• Artisan 4.0.2
• Windows PC

How it's wired:

• Both MAX6675 share SCK (pin 6) and SO (pin 4), with separate CS pins (pin 5 for ET, pin 3 for BT)
• SSR control connected to Arduino pin 9
• Arduino communicates with Artisan via USB/Modbus RTU
• SSR output is wired in series with the hot air gun's live wire

Modbus configuration in Artisan:

• COM3, 19200 baud, 8N1
• ET reads from Device 1, Register 2, Divider 1/100
• BT reads from Device 1, Register 3, Divider 1/100
• Slider "Burner" set to Modbus Command: write([1,4,{}]), Min 0, Max 100
• PID section: Device 1, SV register 5, SV Factor 10
• Control checkbox is ticked in Config > Device

What works:

• ET and BT temperatures display correctly in Artisan
• Moving the Burner slider manually lights up the SSR LED
• The SSR responds correctly to manual slider values

What doesn't work:

• Automatic control, the SSR does nothing on its own
• Ramp/Soak mode doesn't move the Burner slider automatically
• The MODBUS PID Control window is set to Slider Burner, with Ramp/Soak mode and appropriate SV values, but the slider stays at zero during a roast

What I've checked:

• I logged all 16 Modbus registers while Artisan was running with Ramp/Soak active, registers 4 and 5 were always 0, meaning Artisan never writes anything to the Arduino
• Only registers 2 and 3 have values (the temperatures Arduino sends to Artisan)
• The "Control" button turns red when ON is pressed (active state in Artisan 4.x)
• Slider is ticked in the PID Control window, set to Burner, Min 0, Max 100

My question:
How do I get Artisan's Software PID (or Ramp/Soak) to automatically move the Burner slider and write values to the Arduino via Modbus? Is there something specific I need to configure in Artisan 4.x that's different from older versions?

Any help would be greatly appreciated. I'm very close to having a fully working DIY roaster, just this last piece of automation is missing!

Thank you!

[MAKOMO]

PID section: Device 1, SV register 5, SV Factor 10

so you configured Artisan (PID Device not zero) to use the external (to Artisan) PID and not the Artisan built-in software PID

The SSR responds correctly to manual slider values

not moving the SV slider but the heater/burner slider, right?

The PID control on the Artisan side has 3 modes (PID dialog accessible by pressing the CONTROL button):

• manual
• Ramp/Soak
• Background

This setting decides where the Set/Target Value (SV) is taken from. Either manual, by filling in the SV field in this dialog, moving the SV slider or pressing the +-SV buttons, or from the Ramp/Soak specification, of from the loaded background profile.

First step would be to get the manual mode working. Make those SV sliders visible and move them. Artisan will send the updated SV values to your external PID implementation and then this PID implementation should control the heater/burner accordingly. In the best case your selected target temperature is achieved this way. If not, you need to tune your external PID better.

In case you want to use the Artisan built-in PID you need to put a zero as PID Device in the MODBUS dialog.