charting on/off status

I need to chart the on or off status of a device. I would
like for the chart to show a "1" on the y-axis when the
device is on and a "0" on the y-axis when the device is
off. The x-axis would show the time.

If the device comes on at 9:00 am my data recorder records
a record with a value of "1" at 9:00. Data recorder's
next record is a "0" at 9:23 when the device changes to
the off state.

Can someone help me to chart this type of information? In
the end, I have 4 data recorders that I want to plot on
the same chart to determine when the devices are running
at the same time.

thanks,
Greg