RS232: IRP_MJ_WRITE error

Thread Starter

anhnha

Joined Apr 19, 2012
905
I am doing a project and need to communicate between an application
on computer with PLC through RS232 port.
The app send "1" or "0" to PLC. However, sometimes PLC doesn't receive
that. To check what is happening I used AccessPort to monitor.
I am not at work right now, so I can't have the log file but it is
something like the one below.

As you can see in the line #34, the "Result" is nothing and "Time" is 0.00000000.
However, "Data" is still OK ("1" in this case).
Where is the problem in this case?
Is that the app sending is OK because "Data" from the AccessPort is still OK.
The problem is that this data doesn't come to PLC.



Code:
#           Time        Process          Request           Port   Result  Other
33      0.00002222      app.exe       IRP_MJ_WRITE       Serial0 SUCCESS Data: 1
34      0.00000000      app.exe       IRP_MJ_WRITE       Serial0         Data: 1
35      0.00000562      app.exe       IRP_MJ_READ        Serial0 SUCCESS Data: 0
36      0.00000239      app.exe       IRP_MJ_READ        Serial0 SUCCESS Data: 0
 
Last edited:

Thread Starter

anhnha

Joined Apr 19, 2012
905
What is the "Time" means here?
In line #34, Data is 1. Does this mean that the app has completed its task to write that data to RS232 buffer?
I would like to know where the problem come from, the app, PLC or computer driver.
 
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