Applies To:
  • CitectSCADA
  • CitectHMI
Summary:
Question. I am using COMx driver. I have noticed that my I/O devices do not come back online after the COMx has faulted. This fault can occur due I/O device losing the main power or I/O devices getting shut down. When the power is restored to these devices, they never come back online. Only way to bring them bak online is to restart CitectSCADA. Why? 

Solution:
Answer: COMX driver shuts itself down when the power to the I/O devices go down.

You can also get errors like " "ComX readCommBlock status == FALSE: Error 'The I/O operation has been aborted because of either a thread exit or an application request (0x3e3)' " when the power is restored to the IO devices.

COMx will not restart or reinitialise until you restart CitectSCADA. You can use -nt or -nts switches in special options of COMx port to get around this problem.

Below is some explanation on these switches

-nt

With some serial interfaces, line faults can cause the COMX read thread to shutdown. This meant the driver would not recover after the fault. With the -nt option (no terminate), the thread is NOT shutdown. This allows the system to recover.

-nts

Do not terminate at startup if errors occur. Keep retrying to init the driver .For this to work, the driver must do a COMReset in its InitUnit() code, or Cicode should be doing this.

 
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