Theory of Operation
1-2 WFM700 Series Waveform Monitors Service Manual
Communication between modules and the CPU is accomplished via the Main
Interface board using two main control busses (PCI and Serial) and two RS232
connections. The Input Modules and Real-Time Display module use the PCI bus.
The Reference Module uses the Serial bus. The Front Panel uses RS232 to
communicate with the CPU which interprets the information and sends the
commands to the appropriate modules. The CPU also communicates with the
Environmental Controller (on the Main Interface board) via an RS232 connec-
Power for the WFM700 is provided by the power supply module. The power
supply module accepts line input voltages within the range of 100 VAC to
240 VAC. Anytime line input voltage is supplied to the power supply module, a
+5 V housekeeping supply is activated, providing power to the front panel
ON/STBY switch and to the Environmental Controller (EC) on the Main
Interface board. Pressing the ON/STBY button activates the main power supply
(within the Power Supply module), providing power to the entire instrument and
Once the power supply stabilizes, the CPU module polls all slots (via the PCI
bus and Serial Control bus) to determine the installed modules.
Individual Module Descriptions
The following descriptions provide more detail about the individual functions of
each instrument board or module.
The Front Panel Processor board sends all front panel actions (including the
touch screen) to the CPU board via the RS232 Bus.
The LCD panel displays the video output from the Main Interface board via the
VGA Mux. The Backlight board supplies the high voltage necessary to drive the
backlight for the LCD panel.
Front Panel Processor
LCD and Backlight