SOURce:MODule:CLOCk:FREQuency_950

34980A

previous page next page

SOURce:MODule:CLOCk:FREQuency

Syntax

SOURce:MODule:CLOCk:FREQuency {<frequency>|MIN|MAX|DEF}, <slot>

SOURce:MODule:CLOCk:FREQuency? [{MIN|MAX}, ] <slot>

Description

This command sets the frequency of the external clock output on the 34950A Digital I/O Module in the specified slot. The external clock frequency is derived from the internal 20 MHz timebase clock on the module. Once enabled, the clock signal is output from Pin 62 on the module's D-Sub connector (connector P2).

This command is also used with the 34951A Isolated DAC Module. Click here to view the corresponding information for use with the 34951A.

Parameters

Name	Type	Range of Values	Default Value
<frequency>	Numeric	Desired frequency between 10 Hz and 20 MHz. The module rounds the specified frequency to the nearest integer divisor of 40 MHz (where n = 2 to 4E+6): 20 MHz/n For example, 20 MHz, 10 MHz, 6.666 MHz, 5 MHz, 4 MHz, 3.333 MHz, etc. MIN = 10 Hz, MAX = 20.0 MHz	1 kHz
<slot>	Discrete	{1\|2\|3\|4\|5\|6\|7\|8}	This is a required parameter

Remarks

To enable the specified frequency to be output from the module, use the SOURce:MODule:CLOCk:STATe command.
If desired, you can use the SOURce:MODule:CLOCk:LEVel command to set the logic "1" voltage level for the external clock output.
A Factory Reset (*RST command), Instrument Preset (SYSTem:PRESet command), and Card Reset (SYSTem:CPON command) will disable the clock output and reset the external clock frequency to 1 kHz.

Return Format

The query command returns the clock output frequency in the form "+1.00000000E+03". Note that since the module rounds to the nearest integer divisor of 20 MHz, the value returned may be different than the frequency you specified. For example, if you specify 3.0 MHz, the query command will return 3.3 MHz (20 MHz/6). If you specify 300 kHz, the query command will return 298.5 kHz (20 MHz/67).

Examples

The following command sets the external clock frequency for slot 3 to 5 kHz (no rounding required) and enables the output.

SOUR:MOD:CLOCK:FREQ 5E+3,3
SOUR:MOD:CLOCK:STATE ON,3 !Enable clock output

The following command sets the external clock frequency for slot 3 to 300 kHz (rounded to 298.507 kHz) and enables the output.

SOUR:MOD:CLOCK:FREQ 300E+3,3
SOUR:MOD:CLOCK:STATE ON,3 !Enable clock output

The following query returns the actual external clock frequency for slot 3.

SOUR:MOD:CLOCK:FREQ? 3

Typical Response: +2.98500000E+05