Digital Thermostat Temperature Controller

The W1209 is an incredibly low-cost yet highly functional thermostat controller. With this module, you can intelligently control power to most types of electrical devices based on the temperature sensed by the included high-accuracy NTC temperature sensor. Although this module has an embedded microcontroller no programming knowledge is required. 3 tactile switches allow for configuring various parameters including on & off trigger temperatures. The onboard relay can switch up to a maximum of 240V AC at 5A or 14V DC at 10A. The current temperature is displayed in degrees Centigrade via its 3-digit seven-segment display and the current relay state by an onboard LED. 

Module Power:

The module is powered from 12VDC which is connected to the screw terminal block.  This can come from an AC wall adapter or a similar power source.

Display:

• The module has a 3-digit display composed of 0.28″ high red 7-segment displays.
• The module will always display the current temperature measurement by default.  Once you stop pushing buttons, after about 5 seconds the display will default back to displaying the temperature.
• If you apply power to the module without the sensor attached, it will display ‘LLL‘.  If you plug in the sensor, the current temperature will be displayed which is generally in the 20-25C range.

Buttons:

There are 3 buttons on the module that you can fiddle with:

• SET = Momentary press sets trigger temperature.  Long press enters parameter setting mode
• ‘+’ =    Increment setting
• ‘-‘ =     Decrement setting

Setting Trigger Temperature:

• To set the trigger temperature which is the temperature that you want something to happen, press the SET button and the display will start flashing.  The value being displayed is the trigger temperature.  As shipped, this will be set to 28C.
• Using the +/- buttons, the value can be incremented or decremented in 0.1C steps.  Holding one of these buttons down will fast increment/decrement the value.
• Pressing the SET button saves the value that you have set and returns to the temperature display.  Alternatively, if you stop pressing buttons rather than pressing SET, after a 5-8 second delay the value will be saved and the display will revert back to the temperature display on its own.

Setting Parameters:

Because the user interface is limited to a 3-digit display and 3 push buttons, setting parameters can seem a little daunting at first, but it is actually quite easy to use as explained in this section.

To enter the parameter setting mode, you long press the SET button for about 3 seconds.  When the button is released the display will show ‘P0‘ which is the first parameter setting.  You may find that you need to long press the button twice before P0 is displayed.  Once in parameter setting mode, pressing the +/- keys allow you to scroll between each of the parameters that can be set.

There are 9 parameters that can be programmed into the module:

• P0 = (Heat / Cool) sets whether the relay is energized or de-energized when trigger temperature is reached.
• P1 = (Hysteresis) sets the difference in degrees between the Trigger temp and when relay changes state
• P2 = (Max Temp) sets the maximum Trigger temp that can be set
• P3 = (Min Temp) sets the minimum Trigger temp that can be set
• P4 = (Temp Correction) sets an offset to use for the displayed value
• P5 = (Delay) sets a time delay between when the Trigger temp is reached and when the relay is switched
• P6 = No information
• P7 = (Alarm) sets a high temperature ‘alarm’ trip point
• P8 = No information

• Temperature Control Range: -50 ~ 110 C
• Resolution at -9.9 to 99.9: 0.1 C
• Resolution at all other temperatures: 1 C
• Measurement Accuracy: 0.1 C
• Control Accuracy: 0.1 C
• Refresh Rate: 0.5
• Seconds Input Power (DC): 12V
• Relay Specs (MAX): 240V AC at 5A or 14V DC at 10A
• Measuring Inputs: NTC (10K 0.5%)
• Waterproof Sensor: 0.5M Output: 1 Channel Relay Output,
• Relay Output Current: 10A 
• Power Consumption Static Current: <=35mA Current: <=65mA 
• Environmental Requirements Temperature: -10 ~ 60 C
• Humidity: 20-85% 
• Dimensions (mm): 48 (L) x 40 (H) x 15 (H) 

• 1 x Digital Thermostat Temperature Controller

For further information, you can refer to this document.