The external pressure library works to retrieve the pressure measurements from an external pressure sensor, and write the pressure value back to the SME. 


The followings steps describe the guidelines to design a custom library that is compatible with RCP software:


  1. Library should be built in LabVIEW 2019 32 bits. 
  2. Library can have any name.
  3. The library MUST have a main vi called “VIS_External_Pressure.vi” if this VI is not found inside the library the software will throw an error. 
  4. The “VIS_External_Pressure.vi”, should have one input and three outputs: 
    1. input
      1. command: and enum (U16 data type) of four states: 0= Initialize, 1= Configure, 2= Read Pressure, 3= Close
    2. output
      1. Pressure: float data type. Units of bar
      2. Device ID: a string with a device identifier
      3. Temperature: float data type. Units of Celsius. 
  5. The “VIS_External_Pressure.vi” should execute only ONCE every time is called. 
  6. The “VIS_External_Pressure.vi” must have this exact connector pane, with the inputs and outputs. 

 

VIS_External_Pressure.vi states

As mentioned above, the command is an input that determines the state of the VI. 

The software calls the states in this order: 

  1. Configure: This state is called only when the library is selected for the first time. Recommendation: Use this state in your library to call any needed configuration, and save it in a configuration file. 
  2. Initialize: This state is called only once when the pressure readings start. Use this state of the VI to call any initialization that is needed, or for reading the configurations from your config file. 
  3. Read Pressure: This state is called every 500 ms and should make the sensor readings. Use this state for the actual communication with your device. This is the most important state. All others can be left blank or with no action, but this state generates the pressure outputs. 
  4. Close: This state is called on exit of the software.