Q49376: COM Port Time-Out Halts Redirection of CVP to Remote Terminal
Article: Q49376 Product(s): See article Version(s): 2.20 2.30 Operating System(s): OS/2 Keyword(s): ENDUSER | | mspl13_basic Last Modified: 27-OCT-1989 When using protected-mode CodeView (CVP) under OS/2, there is a problem with the serial communications (COM) ports timing out after 60 to 90 seconds of inactivity. This time-out makes it essentially impossible to do remote terminal debugging with CVP. Once the time-out occurs, no further input is accepted from the remote terminal. The only workaround is to quit CodeView and begin again, or to do a break and then restart the redirection to the COM port. The CodeView Debugger allows redirection of input and output to a file or device. This procedure is commonly used to set up a remote (dumb) terminal for CodeView input and output, while the PC screen is used for displaying the program input and output. The terminal is connected through a COM port, which eliminates the need for a second video adapter as is required when using two monitors with the /2 option. Entering "=COM1" at the CodeView command prompt enables input and output redirection to the device designated as COM1. This debugging arrangement works great with CodeView under MS-DOS, but it becomes unworkable with CVP under OS/2 because the internal calls that are used to set up the redirection do not account for time-outs due to inactivity. Thus, if you are entering commands from the remote terminal at a steady pace, everything proceeds smoothly. However, if you stop and wait for more than about 60 seconds without doing any input, the port will time-out and leave you stranded because the keyboard no longer responds. In a normal debugging session, it is quite likely that there would be many instances greater than 60 seconds where input is not yet needed or desired; therefore, this situation quickly becomes intolerable. The only way to regain control is to enter CTRL+C at the PC keyboard, which ends the redirection. At that point, you could enter "=COM1" again on the PC keyboard to restart the redirection if you so desired.
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