Sleep mode hanging program

[CaKiwi]

I have a vb program on a win98 machine which communicates with a control through the serial port. If there is no mouse or keyboard activity, the machine goes into sleep mode and the program hangs. I have turned off sleep mode but I am wondering if there is a way within my program to prevent sleep mode from being activated.

I posted this in the other vb forum ( thread222-377469 )and got some general responses, but I am wondering if anyone here can suggest something specific.

TIA CaKiwi

 

[kesm]

Hi CaKiwi.

There is three possibilities for your system hanging:
1: A Known Bug in win16 code ported from Windows 3.1,
(code never returns in Windows 95 because the EV_RING event is not detected by the system) has been reported in early win98 versions.

2: The WaitForSingleObject waits infinately long.
(So DoEvents)
3: flow control has blocked the transmission.
(So Error Checks)

You can be a real un-tidy coder and post mouse_events to windows, but this will not free up the EV_RING event, or flow controll blocked transmission, which will result in needing a reset.

I would suggest that you Log onto microsoft.com and look up the EV_RING in the support and patch win98, then include error handling in your coms code along with DoEvents and background processing.

 

[CaKiwi]

Hi kesm,

I am using Windows 98 SE, so can I assume the bug you mentioned has been fixed?

At the time the system goes into sleep mode, the vb program is in a loop waiting for data to arrive at the serial port and doing a doevents call each time round the loop. The device I am communicating with has sent a DC1 character and I am waiting for a DC3 before resuming transmission. I am not checking for data communication errors at that point, although I probably should be, but I don't think errors are causing this problem.



CaKiwi