Serial DTR line on reboot

I'm working on a controller board that connects to the PC via the serial port. We'd like to be able to reboot this board from the PC. I have another system at work that seems to accomplish this using the DTR line, e.g. pulses t开发者_JS百科he line for a certain period to trigger a reboot. I would like to find information on what the standard state of the line is (e.g. is it usually logic high or low) and what happens to the line when the PC reboots (e.g. does it de-assert for a period).

Thanks to anyone who can help, Fred

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Some updated information about my USB SerialPorts(usbsp).

I rebooted a couple of times and my usbsp does go through some sequence of raising and lowering signals when my PC reboots. It also does this when any(a couple I tried) new USB device is plugged in.

So beware if you are using usbsp's signals at boot time to control a device.