Priority Select

The function block supports 4 enable inputs enable1, enable2, enable3, enable4 and 4 inputs in1, in2, in3, in4. The single output pin is Out. This function allows one to four inputs in any combination to be individually enabled to override the default. The output is the input with its highest priority enabled TRUE.

Logic Inputs

Input Name Input Value Logic Value Description
enable1-4 VAL != 0.0 1  
  0 0  
  unconnected 0  
  invalid 0  

Analog Inputs

Range
Input Name Low High Input Value Description
in1-4 >=- infinity <+ infinity unconnected val = invalid
invalid val = invalid

Setpoint

Name Range/Value Description
In1AsDefault Yes Output is set to Input 1 even if all Enable Inputs 1-4 are invalid.
  No Output is set to Invalid if all Enable Inputs 1-4 are disabled.

Output

Output Name Range Description
OUTPUT Any floating point value The output is set to the input that is enabled.
  • If all inputs are unconnected, output is invalid
  • If all Enable inputs are disabled, and all inputs are invalid, output is invalid
  • If SetIn1asDefault is enabled, output is Input1, even if all Enable inputs are disabled.
  • When SetIn1asDefault is disabled/Enabled and atleast one Enable input is enabled, output is the input with its highest priority enabled TRUE. The priority order among Enable inputs is:
  1. Enable1
  2. Enable2
  3. Enable3
  4. Enable4

Based on the In1asDefault option and the Enable options selected, the output is set as Input as follows:

In1asDefault Enable Inputs 1-4 Inputs 1-4 Output
Enabled Disabled   Output is set to Input1
  Enabled   Output is set to highest enabled input.
Disabled Disabled   Output is invalid
      Output is set to one of the Inputs 1-4 based on the priority order:
  1. Enable1
  2. Enable2
  3. Enable3
  4. Enable4

Note:

  • Enable 1 has highest priority and if it is enabled, output is taken as Input1.
  • If Enable 1 is disabled, Enable 2 has the next highest priority and if Enable 2 is enabled, output is taken as Input 2.
  • Enable 3 has the third highest priority and if Enable 1 and Enable 2 are disabled, output is taken as Input 3.
  • Enable 4 has the least priority and output is set to Input 4 only if Enable 1-3 are disabled.