monitoring video displays

Is there a way for the computer to determine if the video display
is working. I'm writing a program to query different pieces of
hardware and would like to query the monitor to see if it is
working.

I've seen a way using the 'read-edid' program ( (E)DID over
VBE/DDC) to query it for data. An error occurs if the monitor
is off. This might not be suitable for ongoing monitoring
thought -- there are warnings that it might not work ( or
worse).

The systems I'm monitoring are using ati cards using xfree86
under redhat (7.3 or 9.0).

If there is a method that works under a different operating
system, then let me know. I will look into making it work
with my systems.

b²

On Wed, 17 Mar 2004 15:09:53 GMT, H Brett Bolen
wrote:

Is there a way for the computer to determine if the video display
is working. I'm writing a program to query different pieces of
hardware and would like to query the monitor to see if it is
working.

I've seen a way using the 'read-edid' program ( (E)DID over
VBE/DDC) to query it for data. An error occurs if the monitor
is off. This might not be suitable for ongoing monitoring
thought -- there are warnings that it might not work ( or
worse).

The systems I'm monitoring are using ati cards using xfree86
under redhat (7.3 or 9.0).

If there is a method that works under a different operating
system, then let me know. I will look into making it work
with my systems.

b²

You can find out if the monitor is connected, turned on, and some
specifications. It could be a completely blank screen, and you would never
know. Common failures, such as poor focus or one color gun dead will not be
detectable.

Best you can do with software on a PnP monitor is check that yeah, there
is a monitor connected, and these are its reported specs.

JT

JT wrote:

On Wed, 17 Mar 2004 15:09:53 GMT, H Brett Bolen
wrote:


Is there a way for the computer to determine if the video display
is working. I'm writing a program to query different pieces of
hardware and would like to query the monitor to see if it is
working.

I've seen a way using the 'read-edid' program ( (E)DID over
VBE/DDC) to query it for data. An error occurs if the monitor
is off. This might not be suitable for ongoing monitoring
thought -- there are warnings that it might not work ( or
worse).

The systems I'm monitoring are using ati cards using xfree86
under redhat (7.3 or 9.0).

If there is a method that works under a different operating
system, then let me know. I will look into making it work
with my systems.

b²


You can find out if the monitor is connected, turned on, and some
specifications. It could be a completely blank screen, and you would never
know. Common failures, such as poor focus or one color gun dead will not be
detectable.

Best you can do with software on a PnP monitor is check that yeah, there
is a monitor connected, and these are its reported specs.

JT


I'm aware that there can be no way of being 100% sure that the
monitor is displaying data correctly, but I'd like a quick
way to determine if one is connected. Doesn't some BIOSes
detect if there is no vga present on boot?

Is there a method to determine if the monitor is online ( say,
it thinks it is working)?

thx
b\375