974 CCNIM Quad 100-MHz Counter/Timer

 Specifications

PERFORMANCE

COUNT CAPACITY 8 decades, all sections

COUNTING RATE 100 MHz for negative inputs, all sections; 25 MHz for positive inputs, all sections.

TIME BASE 0.1-second or 1-minute increments derived from an internal 1-MHz crystal-controlled oscillator. Also accepts external input through rear-panel BNC labeled Ext In. Selectable from front panel or through computer control.

PULSE PAIR RESOLUTION 10 ns for negative inputs, 40 ns for positive inputs.

INDICATORS

COUNTER DISPLAY 8 characters, 7 LED segments per character plus decimal point.

TIMER PRESET 2 characters, 7 LED segments per character. Presettable from front panel or through computer control. Displayed in an M X 10^N format.

DISPLAYED COUNTER Single-digit display indicates which counter channel is being displayed.

CONTROL 2 LEDs indicating either Remote mode operation (front-panel controls locked out) or Local mode operation (front-panel controls operative).

0.1 SEC Single LED illuminates when the 0.1-second time base is selected.

1 MIN Single LED illuminates when 1-minute time base is selected.

EXT Single LED illuminates when Ext time base is selected or when using counter channel 1 as a counter.

COUNTER OVERFLOW 1, 2, 3, AND 4 Four separate LEDs illuminate when the corresponding counting channel exceeds the capacity of the counting channel.

GATE Single LED illuminates during an active counting interval.

CONTROLS

DISPLAY TEST Push-button switch illuminates all segments of every 7-segment display.

RESET Push-button switch resets the internal counting channels to zero and turns Off the overflow indicators.

STOP Push-button switch selects the noncounting condition for all counting channels.

COUNT Push-button switch enables the counting condition for all counting channels provided the Gate input is not held below +1.5 V and the time is not at the preset count condition.

DISPLAY SELECT Push-button switch selects the counting channel whose contents will be displayed.

DWELL TIME Single-turn control with a switch at the full counterclockwise setting for Off. Off inhibits recycle operation of a preset counting interval. When the control is turned clockwise away from Off, it permits recycling with a dwell time between counting intervals that can be adjusted from 0.3 s to ~15 s. This control is disabled when computer control is in effect.

M Push-button switch used to set the timer preset value. The "M" preset value [preset = (M X 10^N) time base] is incremented each time the button is pressed . Maximum value = 9.

N Push-button switch used to set the timer "N" preset value. The N preset value is incremented each time the button is pressed. Maximum value = 7.

TIME BASE SELECT Push button used to select the internal time base of 0.1 Sec or 1 Min or the Ext In rear-panel input for external time base.

IEEE CONTROL SWITCH (S-1) An 8-position slide switch accessible through cutout in left side panel. Sections 1 through 5 select the talk and listen address to which the Model 974 responds on the IEEE-488 bus. Section 6 selects the recycle/one-cycle mode. In recycle, a reset is automatically generated after the counter contents are transferred to a buffer. In one-cycle, a reset must be generated by an external command. Section 7 is not used. Section 8 selects the interface that will be used to communicate with the computer or terminal. "On" selects RS-232-C; "Off" selects the IEEE-488 interface.

SERIAL INTERFACE CONTROL (S-2) An 8-position slide switch accessible through a cutout in the left side panel. Sections 1 through 4 select the counting channels whose contents will be transmitted when data is transferred to the computer or terminal. If the corresponding switch is set for print, the data for that counting channel will be transmitted; if set to the skip position, the data will not be transmitted. Section 5 selects the length of the data byte that will be transmitted over the serial communications interface. "On" selects 7 data bits; "Off" selects 8 data bits. Section 6 is used to enable or disable the parity generation and checking when characters are sent or received over the serial interface. If parity is enabled, Section 7 selects either odd or even parity mode. Section 8 selects whether one or two stop bits are added to the character transmitted over the serial interface.

BAUD RATE SELECT (S-3) A 4-position slide switch accessible through a cutout in the left side panel. This switch selects the baud rate at which characters are transmitted and received over the serial communications interface.

INPUTS

COUNTERS 2, 3, AND 4 Front-panel BNC connectors accept positive unipolar signals; minimum pulse width above threshold, 20 ns at 50% duty cycle. Z_in = 1 kW to ground. Threshold is fixed at +1.5 V. Input protected to +25 V, dc-coupled.

Changing the input connector to the counter board permits independent selection of NIM-standard fast negative logic pulses, 14 mA into 50 W. Minimum pulse width above threshold is 4 ns. Input is dc-coupled, 250-mV fixed threshold.

COUNTER 1 OR EXT Rear-panel BNC connector accepts NIM-standard positive unipolar signals; minimum pulse width above threshold, 20 ns at 50% duty cycle. Z_in = 1 kW to ground. Threshold is fixed at +1.5 V. Input protected to +25 V, dc-coupled.

Changing the input connector to the negative input permits selection of NIM-standard negative logic pulses, 14 mA into 50 W. Minimum pulse width above threshold is 4 ns; threshold fixed at –250 mV; input is dc-coupled.

MASTER GATE Rear-panel BNC connector accepts NIM-standard positive logic signal to control counter input gate for all counting sections and the front-panel count LED indicator. A signal >+3 V or open circuit allows counting; a level of <+1.5 V inhibits counting. Protected to +25 V. Driving source must be capable of sinking 0.5 mA positive current during inhibit.

GATES 1, 2, 3, AND 4 Rear-panel BNC connectors accept NIM-standard positive logic signal to control individual counting channel inputs. A signal >+3 V or open circuit allows counting; 25 V maximum. A level of <+1.5 V inhibits counting. Driving source must be capable of sinking 0.5 mA of positive current during inhibit.EVENT Rear-panel BNC connector accepts standard positive logic pulse to increment the event counter. Signal must exceed a level of +2.5 V for a period of >100 ns to increment the event counter. Maximum frequency of input signal is 4 kHz.

RESET Rear-panel BNC connector accepts standard positive logic pulse to remotely reset all counting sections to zero. A signal of >+3 V is needed to reset; a signal of <+1.5 V or open circuit is required to not reset. Protected to +25 V; minimum pulse width is 100 ns; Z_in = 6 kW to ground, dc-coupled.

OUTPUT

INTERVAL Rear-panel BNC connector furnishes a positive level during the counting interval. Nominally +5 V; Z_o = 30 W.

INTERFACES

IEEE-488 24-pin, rear-panel-mounted standard IEEE-488 bus connector.

SERIAL RS-232-C or 20-mA current loop signal on a single, 25-pin rear-panel-mounted connector.

ELECTRICAL AND MECHANICAL

POWER REQUIRED +6 V, 1.6 A; +12 V, 70 mA; –12 V, 290 mA.

WEIGHT
Net 2.4 kg (5.2 lb).
Shipping 3.7 kg (8.2 lb).

DIMENSIONS NIM-standard double-width module 6.90 X 22.13 cm (2.70 X 8.714 in.) front panel per DOE/ER-0457T.

ORDERING INFORMATION