Features

• >250 MHz count rate capability,
  1015–1 count capacity
• Complete computer control
  via RS-232 interface
• Standalone programming
  capability
• High resolution timer with
  0.1 μs preset capability
• Self test mode
• Up to eight user-defined
  operating configurations

Description

The Model 512 Dual Counter/Timer offers greater than 250 MHz count rate capability for the most demanding counting applications. In addition, the 512’s counters have a count capacity of 1015–1. Photon counting applications, or experiments requiring pulse-pair resolutions of about 4 ns, are now no longer limited by the counter/timer.

The Model 512 offers standalone performance in addition to being completely computer-controllable. Standalone operations are menu driven, and illuminated pushbuttons are used to select displayed data, operating mode, count/stop/reset operation, and for manual programming. All functions, including threshold settings, are programmable through either the instrument’s front panel or the RS-232 interface.

The Model 512 also includes two timers. The nongateable standard timer has a selectable resolution of 0.01 seconds or 0.01 minutes, and is programmable from 0.01 to 99 999 999.99 seconds/min. The standard timer is software-based, so both hardware counting channels are available for counting.

The high resolution timer is gateable and fully programmable, with a resolution of 0.1 μs from 1 μs to 9.999 999 9 seconds, and 10 s resolution up to 99 999 990.0 seconds. Depending on the mode of operation, the high resolution timer uses channel 1 or channel 2, so that only one counting channel is available when the high resolution timer is used. Also included is a programmable recycle timer which resets and initiates a new counting interval at the completion of a cycle.

The Model 512 includes two high speed counters capable of greater than 250 MHz operation. Polarity, threshold, and counter/timer presets are all fully front-panel programmable. Depending on the mode of operation, channel 1 may be defined as a preset counter or preset high resolution timer. Also, depending on the mode selected, channel 2 may be defined as a high resolution interval timer. When channel 1 is defined as the preset counter, it is fully programmable from 1 to 99 999 999 counts. Both counter channels have a dynamic range of 1015–1 counts, so overflow outputs are not required. Both channels are gateable from the front-panel GATE inputs in both counter and timer configurations.

The Model 512 includes a software-based event counter which increments at the completion of each counting interval. If the event counter value equals the event preset register, further count intervals are inhibited (recycle is disabled).

Eight different user-defined operating configurations: presets, input polarity/threshold, operating modes, etc., may be saved in non-volatile memory and recalled on command. In addition, one of these configurations may be selected as the power-on default configuration. A selftest mode allows confirmation of proper counter/timer functioning at power on. The built-in RS-232 serial communications interface provides computer control of all Model 512 functions except the communications parameters.