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This schematic shows the wiring that is in place to allow the control computer to monitor the state of the ion pump controllers. This includes reading the ion pump current, reading the state of the front panel rotary switch, and remotely activate the start pushbutton. The two sheets of this schematic show the connections for the CCD chamber, sheet 1, and the N2 vessel, sheet 2. In that both sheets are identical only sheet 1 will be described.

To the left of the page is Galil controller #2. The ion pump controllers are connected to the controller via the expansion I/O (center of diagram) and it's analog inputs via the Analog input card (lower left). The Varian Ion Pump Controllers (right side of drawing) have been modified by UCO/Lick for remote operation. This is accomplished by 1) detecting the current flow to the ion pump, 2) supplying an analog voltage output that is proportional to the current, 3) supplying an input that can mimic the action of pushing the reset button, and 4) sending back the state of the controller's AC as seen after the intervening shut down relay. The modifications, in essences, shut down the AC power to the controller if the current raises above a safe level of about 50 ma. Large currents, that may occur if the dewar warms up, could damage the actual ion pump. For more details on the UCO/Lick modifications, see EL-1027 in the Miscellaneous Drawings section of this manual. Also, the rotary switch that selects the current range for the controller's front panel meter has been modified to close a set of contacts when the switch is in the correct position.

For the chamber controller, the Galil monitors the AC power via input channel 22, bit 71, of Opto-22 panel #5. The current select switch input is monitored via channel 6, bit 55. The remote activation of the 'reset' pushbutton is handled by output channel 14, bit 39, of Opto-22 panel #4. The final function is the monitoring of the ion pump current. The signal from the ion pump controller is applied to input 2A of the Analog Input Card attached to Galil controller #2. See the page on the Analog Input card for more details on working with this card.

 

Chamber Ion Pump Controller

 

Vessel Ion Pump Controller