1-1. INTRODUCTION 1-2, The Fluke Model 2205A Switch Controller is an instrument mainframe which accepts plug-in options for multi-function switching of analog signals. The 2205A is designed for automatic test equipment (ATE) and data acquisition system use. The switch modules functionally accomodate the three fundamental requirements for switching in instrumentation systems: signal aquisition, distribution, and control. 1-3. The key feature of the 2205A is its modular configuration which supports concurrent multi-function switching. Other important features include: low thermal design for low level measurment applications, dual guarded internal scanner bus for precision resistance measurements or parallel scanning, and expansion capability. In its basic form, the 2205A is capable of physically housing up to 10 switch modules and can be expanded to electrically control up to 100 switch modules. The 2205A is also compatible with companion instruments for system application. 1-4. The front panel of the 2205 A features the controls and indicators necessary for manual (local) control of the switch modules. Commands are entered on a calculator- type keyboard (0-9) and are displayed on a three-digit LED display. Three control buttons (BLOCK RESET/T.C. REF. JUNCTION, LOCAL, and INCREMENT) are provided for commanding thermocouple reference junction measurements or module resets (depending on type of module addressed), local recall (remote-to-local), and channel increment. 1-5. The rear panel of the 2205A includes a remote interface connector (for use on IEEE-488 or RS-232-C Standard buses), an extender connector to add extention mainframes, an analog connector for connecting the internal scanner buses to an external instrument such as a digital multimeter (DMM), and a trigger output connector for initiating a DMM reading. An analog output cable for connection between the 2205A and a system type DMM is supplied with the 2205A. The remote interface cable, the trigger output cable (coax with BNC connectors), and an extender cable (which is required when adding a extension chassis) are options and are not included with the unit. Extender cables are available as accessories and are fabricated by the factory to meet particular cable length requirements. Cable lengths from 3 to 1500 feet may be used depending upon the extention mainframe employed. 1 -6. The slots for the switch modules are also located at the rear of the 2205A. They consist of a series of 10 pcb slots (blocks) numbered from 0 through 9. Each slot will accommodate a plug-in relay pcb and an input connector for supplying analog data to the 2205A. The relay pcbs and the input connectors make-up a module are available as options. 1-7. All options and accessories available for use with the 2205A are listed in Table 1-1. Details necessary for specification, installation, operation, and maintenance are given in Section 7 of this manual.