Comparator / 2 Points Regulator

The Comparator / 2 Points Regulator node compares two numeric input values and generates a logic output according to two configurable thresholds.

The node calculates the difference between Input 1 and Input 2:

$$Difference = Input\ 1 - Input\ 2$$

The output is then determined as follows:

• if the difference is greater than Threshold for ON, the node sends 1 to Output;
• if the difference is lower than Threshold for OFF, the node sends 0 to Output;
• if the difference is between the two thresholds, Output maintains its previous state.

The interval between the ON and OFF thresholds creates a hysteresis area that prevents frequent switching when the input values fluctuate around the regulation point.

This node can be used, for example, for:

• two-point temperature regulation;
• switching a device according to the difference between a setpoint and a measured value;
• maintaining a stable output when the input value fluctuates;
• controlling heating, cooling, ventilation, or other ON/OFF devices.

For the general operation of the Gate connector, refer to Gate connector.

The node first calculates the difference between the two input values:

$$Difference = Input\ 1 - Input\ 2$$

It then compares the result with the configured thresholds.

When:

$$Difference > Threshold\ for\ ON$$

the node sends 1 to Output.

When:

$$Difference < Threshold\ for\ OFF$$

the node sends 0 to Output.

When:

$$Threshold\ for\ OFF \leq Difference \leq Threshold\ for\ ON$$

the node does not change the output. Output maintains its previous value.

Assume the following thresholds are configured:

• Threshold for ON = 1;
• Threshold for OFF = -1.

The node operates as follows:

The node can be used as a two-point regulator by connecting:

• the temperature setpoint to Input 1;
• the measured room temperature to Input 2;
• the heating command to Output.

Assume:

• setpoint: 21 °C;
• Threshold for ON: 0.5;
• Threshold for OFF: -0.5.

The difference is calculated as:

$$Difference = Setpoint - Measured\ temperature$$

The resulting behavior is:

The hysteresis interval prevents the heating output from switching continuously when the measured temperature fluctuates close to the setpoint.

To verify the node using Offline Simulation:

1. Connect two input nodes to Input 1 and Input 2.
2. Configure Threshold for ON and Threshold for OFF.
3. Connect Output to a node that allows the resulting value to be monitored.
4. Enable Await all inputs if the comparison must start only after both inputs have been initialized.
5. Start Offline Simulation.
6. Set the inputs so that the calculated difference is greater than Threshold for ON.
7. Verify that Output changes to 1.
8. Set the inputs so that the difference remains between the two thresholds.
9. Verify that Output maintains its previous state.
10. Set the inputs so that the difference is lower than Threshold for OFF.
11. Verify that Output changes to 0.

• Both inputs must contain valid numeric values.
• Use Await all inputs when the comparison must not be performed before both inputs have been initialized.
• Configure Threshold for OFF lower than Threshold for ON to obtain a valid hysteresis interval.
• A wider interval reduces the frequency of output switching.
• A narrower interval provides more precise regulation but may cause more frequent switching when the input values fluctuate.
• Verify the order of Input 1 and Input 2, because reversing them also reverses the sign of the calculated difference.
• If the Gate connector is used, make sure that it receives a valid value; otherwise, the node may remain disabled.

• Logic Module
• Analog nodes
• PID Controller
• Pulse Width Modulator
• Range Verifier
• Threshold Filter