MEASure:COUNter:FREQuency?
Syntax
MEASure:COUNter:FREQuency? [{<gate_time>|MIN|MAX|DEF},] (@<ch_list>)
Description
This command configures the specified counter channels on the 34950A Digital I/O Module to measure the frequency of the incoming signal and immediately initiates the measurement. The results are sent directly to the instrument's output buffer. The specified gate time is the measurement aperture during which the signal data is gathered. For repetitive signals, longer gate times will lead to increased resolution for frequency, period, pulse width, and duty cycle measurements.
The MEASure? command sets the counter parameters to their default values as shown below.
|
Parameter |
MEASure? Settings |
|
Slope |
POSitive (rising edge) |
|
Input Threshold Voltage |
2.5V |
|
Gate Source |
INTernal |
|
Gate Polarity |
NORMal (active high) |
Used With:
34950A Digital I/O Module
Parameters
|
Name |
Type |
Range of Values |
Default Value |
|
<gate_time> |
Numeric |
Desired gate time between 100 ns and 10 seconds, with 50 ns resolution. MIN = 100 ns, MAX = 10 seconds |
1 ms |
|
<ch_list> |
Numeric |
One or more counter channels in the form (@sccc).
|
This is a required parameter |
Remarks
The frequency is measured as: (NumberRisingEdges
– 1)/GateTime. The specified counter channels must detect at least two edges for a valid frequency measurement. The maximum input frequency allowed is 10 MHz.
Sending the MEASure? command clears reading memory and resets the triggering system.
Return Format
The command returns the frequency in hertz for each counter channel specified. The output from this command is affected by the settings of the FORMat:READing commands.
Example
The following command configures counter channel 301 on the module in slot 3 to measure frequency. The value is transferred to the instrument's output buffer. The gate time is set to 1 ms.
MEAS:COUN:FREQ? 1E-3,(@3301)
Typical Response: +3.45600000E+05