Runtime Error 24 & 52

[William Baker]

I have a large four segment program (60k,56k,57k,12k) that
uses serial ports COM1-COM4. Recently I changed COM3 to use
RTS/CTS hardware handshaking.

If the device connected to COM3 is either unplugged or
disconnected, I should get a runtime error 24. I never get this
error in my program. When I try to PRINT #3, I get error 52
and the program crashes. I am unable to trap this error.
Even if I use ON ERROR RESUME NEXT, the program still crashes
at the PRINT #3 statement.

I am using PB DOS 3.2 in a DOS 6.22 environment.

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[Lance Edmonds]

How did you change the port to use RTS/CTS? A cable change? Does the new cable work ok? Did COM3 work OK before the cable change, and did you make any code-changes to your code in the intervening go/nogo period?

Beyond that, we'd probably need to see the code to make any suggestions. However, that code is obviously very large, so I would suggest that you try to write a small test app or strip down your code to the bare essentials just to verify the actual com port code operation.

With such unusual error conditions is it conceivable that there is a problem elsewhere in your program (for example, causing a memory corruption that is affecting seemingly unrelated code). For test purposes, be sure to add $ERROR ALL ON to your code...

I hope this helps!


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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[William Baker]

RTS/CTS enabled on COM3 by the following statement and through
the use of a null modem cable:

OPEN "COM3:9600,N,8,1,DS,CD,IR4" AS #3

Yes, communication works fine. I'm trying to detect runtime
errors caused by the CTS signal not being present (unplugged
cable), which cause a timeout (ERROR 24)
during the initial open statement and subsquent (ERROR 52)
PRINT #3 statements.

I have written a small program to simulate what is happening in
the larger one and it all error traps work fine.

I am using $ERROR ALL ON.

I will prepare an email and send you the code.

Thanks.

William Baker

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