MQTTConnect

NOTE: MQTTConnect() is not required for a persistent MQTT application. MQTT will attempt to connect when enabled with the Device Configuration setting. However, MQTTConnect() can be used to disconnect at a certain time, or after a certain event and then reconnect. The following cell modem application is a common example of when MQTTConnect() is useful.

The following example shows the use of the MQTTConnect() when using the datalogger to control power to a cellular modem using the switched 12V (SW12V) terminal on the datalogger. This is useful in applications where the modem uses more power than the datalogger.

In this example, the TimeIsBetween instruction is used to turn on SW12 for 15 minutes every 60 minutes between 9:00 a.m. and 5:00 p.m.

'In this example, MQTTConnect is used to open an MQTT session when a modem is turned on.

'Declare Variables and Units
Public BattV
Public SW12State As Boolean
Public P3Open as String, P3Close

Units BattV=Volts

'Define Data Tables
DataTable(Table2,True,-1)
  DataInterval(0,1440,Min,10)
  Minimum(1,BattV,FP2,False,False)
EndTable

'Main Program
BeginProg
  'Main Scan
  Scan(5,Sec,1,0)
    'Set SW12-1 to the state of SW12State variable
    SW12(Sw12_1,SW12State)
    'Datalogger Battery Voltage measurement 'BattV'
    Battery(BattV)

    'SW12 Timed Control
    'Turn ON SW12 between 0900 hours and 1700 hours
    'for 15 minutes every 60 minutes
    If TimeIsBetween(540,1020,1440,Min) And TimeIsBetween(0,15,60,Min) Then
      SW12State=True
      
      P3Open = PPPOpen

      MQTTConnect(True)
    Else
      P3Close = PPPClose
      MQTTConnect(False)
      
      SW12State=False
   EndIf

   'Always turn OFF SW12 if battery drops below 11.5 volts
   If BattV<11.5 Then SW12State=False
   'Set SW12-1 to the state of 'SW12State' variable
   SW12(SW12_1,SW12State)

   'Call Data Tables and Store Data
   CallTable Table2
 NextScan
EndProg