COM Port Time-Out Halts Redirection of CVP to Remote Terminal

ID Number: Q49376

2.20 2.30 2.35 3.00 3.10 3.11 3.12 3.50

OS/2

Summary:

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.

More Information:

The CodeView Debugger allows redirection of input from a file or

device. This procedure is commonly used to set up a remote (dumb)

terminal for CodeView input, 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

redirection from 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, there may be occasions when you don't

need or desire input for more than 60 seconds; 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.

Additional reference words: 3.0 3.00 3.1 3.10 3.11 3.12 3.5 3.50