Description
FAN_CMD controls an on/off fan. After the AHU turns on, the damper turns on immediately. The fan turns on after a delay of 60...120 seconds to prevent air duct damage and freezing at low temperatures. The fan stops immediately when low-limit temperature protection is activated.
Function
When "Fan Start/Stop" is "1" (0-OFF/1-ON) and starts timing until "Fan Start Time Delay" is elapsed, "Fan Command" is "1".
When "Fan Fault Alarm" is "1" (0-OK/1-FLT), "Fan Command" is "0".
When "Low limit Temperature Alarm" is "1", "Fan Command" is "0".
Internal logic
Input
PIN | Data type | Unit | Default value | Value/range |
|---|---|---|---|---|
FAN_SS | BOOL | - | 0 | 0-OFF / 1-ON |
FAN_FA | BOOL | - | 0 | 0-OK / 1-FLT |
LLT_ALM | BOOL | - | 0 | 0-OK / 1-FLT |
TIME_DELAY | FLOAT | s | 60 | 0...65535 |
Output
PIN | Data type | Unit | Default value | Value/range |
|---|---|---|---|---|
FAN_CMD | BOOL | - | - | 0-OFF / 1-ON |
Example