Hardware Detect Reset w/o Post Diagnostic Card

[nixie]

Working on a project where I need to know when a system restarts. Cant use PING to watch for when the connection disappears and comes back since the project doesnt have another networked computer at the other end. The post diagnostic card sold here has an LED that shows when the hardware reset happens by sensing the Reset Signal:

LED to monitor the Reset signal

from:
http://www.millennium-solutions.co.uk/diagnostic-tool-pc-computer/post-probe-code-reader-card.html

If this reset signal is the internal reset signal and not the front panel reset status, I could use this to drive a 4N25 optoisolator to know when the reset signal is sent, but was wondering if anyone knew is there was an easier way than tapping into this post diagnostic card for sensing the reset signal.

Best methods of interface are USB, Serial, Parallel to interface with the project I have. Trying to be simplistic and keep costs down. This post diagnostic card would work, but checking to see if there is a better method.

Another idea I had was to drive a relay off of USB or Serial and so when the service ends during a system reboot or shut down, the relay opens until the system boots back up and service starts back up to close the relay contacts. And then enable interfacing with my project. This may be the best method, but figured I'd run it past you all.

Most simplistic idea ... Not sure if reset can be sensed thru USB, Serial, or Parallel if a system is given restart command. Haven't connected my multimeter to my 5V on USB and Serial to see if the power resets during the reboot cycle or if it holds steady thru reboot. If it does cycle the 5V out to these ports, thats awesome and the easiest vs having to run a software service to drive a relay.
Thanks

[nixie]

Guess I am going to go with the option of relay driven by service thru USB. Tested USB port during reboot and 5VDC doesnt cycle. Also looked at pins 2 and 3 with scope for D- and D+ usb communications and nothing there helpful to pin point a warm reboot condition such as a communication flatline vs timed com bursts. I was hoping it would be that easy given that my thumb drives always black out and come back on during reboots, but I guess thats just because their service was terminated during the reboot. Going to close this request for assistance and go with the relay enabled via service to know when the system reboots and comes back online.

[Computer_Commando]

Working on a project where I need to know when a system restarts....

If this reset signal is the internal reset signal and not the front panel reset status, I could use this to drive a 4N25 optoisolator to know when the reset signal is sent, but was wondering if anyone knew is there was an easier way than tapping into this post diagnostic card for sensing the reset signal.

Best methods of interface are USB, Serial, Parallel to interface with the project I have. Trying to be simplistic and keep costs down. This post diagnostic card would work, but checking to see if there is a better method.

Another idea I had was to drive a relay off of USB or Serial and so when the service ends during a system reboot or shut down, the relay opens until the system boots back up and service starts back up to close the relay contacts. And then enable interfacing with my project. This may be the best method, but figured I'd run it past you all....

Front Panel Reset is not a status, it's a control.  I think it pulls the cpu reset line low.

I would stay away from the USB, Serial, or Parallel because the OS has too much control over them.  You want to be at the hardware level.
Get a copy of the PCIbus specification & study it.
http://www.dzjsw.com/shu/bz35.pdf
You may find that it's not as simple as you think.  RST# is not a status.  It is asserted or deasserted by the card.  The Bus provides no useful signals, it only defines the signals & how they are used.  The cards do everything & must conform to the spec to function without interfering with each other.

In the long run, it will be cheaper to find an existing card & use it.  Not sure if the one you selected will work.  It's not clear if it locks the bus after completing it's routine.