Description
This function block set is used to control the start and stop of an on-off electric heater. If the current temperature is below the subtraction of start/stop differential from the setpoint, the heater turns on; if it is above the sum of the start/stop differential and the setpoint, the heater turns off.
The electric heater is required to be switched off immediately in the event of a fault alarm.
Function
When "Fan Command" is "1" (0-OFF/1-ON) and "Temperature Input" is lower than the subtraction of start/stop differential from the setpoint, "Electric Heater Command" is "1".
When "Fan Command" is "1" (0-OFF/1-ON) and "Temperature Input" is greater than the sum of the start/stop differential and the setpoint, "Electric Heater Command" is "0".
When "Fan Command" is "0" (0-OFF/1-ON) or "Sensor Fault Alarm" is "1" (0-OK/1-FLT), "Electric Heater Command" is "0".
Internal logic
Input
PIN | Data type | Unit | Default value | Value/range |
|---|---|---|---|---|
FAN_CMD | BOOL | - | 0 | 0-OFF / 1-ON |
FAULT | BOOL | - | 0 | 0-OK / 1-FLT |
TEMP_PV | FLOAT | °C | 0 | 0...100 |
TEMP_SP | FLOAT | °C | 20 | 0...100 |
HYS | FLOAT | °C | 2 | 0...100 |
Output
PIN | Data type | Unit | Default value | Value/range |
|---|---|---|---|---|
EH_CMD | BOOL | - | - | 0-OFF / 1-ON |
Example
