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Hewlett-Packard 4284A

Hewlett-Packard

4284A

20 Hz to 1 MHz precision LCR meter

lcr_meter SCPI
HP 4284A precision LCR meter front panel
eBay listing photo
Default Address 17
Termination LF
IEEE 488.2 Yes
IDN Patterns
HEWLETT-PACKARD,4284A,*,*AGILENT TECHNOLOGIES,4284A,*,*
Documentation

The HP/Agilent 4284A was the industry-standard precision LCR meter from 1992 until its discontinuation around 2014 (superseded by the E4980A/E4980AL). Covers 20 Hz to 1 MHz with 0.05% basic accuracy. Uses a four-terminal pair (4TP) measurement topology for best accuracy. The command set is quasi-SCPI — mostly SCPI-compliant but with some proprietary extensions (e.g., FUNC:IMP parameter codes). Option 001 adds extended DC bias (up to 40V). Widely used for characterizing capacitors, inductors, ferrites, piezoelectrics, and semiconductor C-V measurements. Many are still in active lab use.

Status Byte

Section titled “Status Byte”
Bit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
UnusedRQS/MSSESBMAVUnusedError QueueUnusedUnused
Not usedRequesting service / Master summary statusEvent status byte summary bitMessage available in output bufferNot usedOne or more errors in error queueNot usedNot used

Use *STB? to read status byte, *SRE to set service request enable register. Bit 2 indicates error queue not empty.

Commands

Section titled “Commands”

IEEE 488.2 Common Commands

Section titled “IEEE 488.2 Common Commands”

Standard IEEE 488.2 commands supported by all compliant instruments

Command Type Description
*IDN? query Identification query — returns manufacturer, model, serial, firmware
Details
Returns (string) — Comma-separated identification
Example: HEWLETT-PACKARD,4284A,MY12345678,01.00
*RST command Reset to factory default state
*CLS command Clear status registers and error queue
*ESE {mask} command Set event status enable register
Details
Parameters
  • mask (numeric) — Bitmask 0-255
*ESE? query Query event status enable register
Details
Returns (numeric)
Example: 0
*ESR? query Read and clear event status register
Details
Returns (numeric)
Example: 0
*OPC command Set operation complete bit in ESR when all pending operations finish
*OPC? query Returns 1 when all pending operations complete
Details
Returns (numeric)
Example: 1
*SRE {mask} command Set service request enable register
Details
Parameters
  • mask (numeric) — Bitmask 0-255
*SRE? query Query service request enable register
Details
Returns (numeric)
Example: 0
*STB? query Read status byte register
Details
Returns (numeric) — Status byte value
Example: 0
*TST? query Self-test; returns 0 for pass, non-zero for fail
Details
Returns (numeric)
Example: 0
Note: Takes several seconds to complete
*TRG command Trigger measurement from bus (requires trigger source BUS)

Measurement Function

Section titled “Measurement Function”

Select the impedance parameter pair to measure. The 4284A always measures a primary and secondary parameter simultaneously.

Command Type Description
FUNC:IMP {parameter} command Select measurement function (impedance parameter pair)
Details
Parameters
  • parameter (enum) — Impedance parameter pair code (see impedance_parameters for full descriptions) Values: CPD, CPQ, CPG, CPRP, CSD, CSQ, CSRS, LPD, LPQ, LPG, LPRP, LSD, LSQ, LSRS, RX, ZTD, ZTR, GB, YTD, YTR
Example FUNC:IMP CPD
Note: CPD = parallel capacitance + dissipation factor. Use parallel model (Cp) for high-impedance DUTs, series model (Cs) for low-impedance DUTs.
FUNC:IMP? query Query current measurement function
Details
Returns (string)
Example: CPD
FUNC:IMP:RANG {range} command Set impedance measurement range manually
Details
Parameters
  • range (numeric) — Impedance range in ohms (1 to 100e6) or MIN|MAX
Note: Manual ranging avoids auto-range settling time
FUNC:IMP:RANG? query Query current impedance range
Details
Returns (numeric)
Example: +1.00000000E+03
FUNC:IMP:RANG:AUTO {state} command Enable/disable impedance auto-ranging
Details
Parameters
  • state (enum) Values: ON, OFF
FUNC:IMP:RANG:AUTO? query Query auto-ranging state
Details
Returns (string)
Example: 1

Frequency

Section titled “Frequency”

Configure the test signal frequency. The 4284A covers 20 Hz to 1 MHz.

Command Type Description
FREQ {value} command Set test signal frequency
Details
Parameters
  • value (numeric) — Frequency in Hz (20 to 1e6) or MIN|MAX
Example FREQ 1E3
Note: Frequency resolution is 4 digits or 1 mHz, whichever is larger
FREQ? query Query current test frequency
Details
Returns (numeric)
Example: +1.00000000E+03
LIST:FREQ {f1},{f2},... command Set list of frequencies for list sweep mode (up to 201 points)
Details
Parameters
  • f1,f2,... (numeric_list) — Comma-separated frequency values in Hz
Example LIST:FREQ 100,1E3,10E3,100E3,1E6
LIST:FREQ? query Query list sweep frequency points
Details
Returns (string) — Comma-separated frequency values

Signal Level

Section titled “Signal Level”

Configure the AC test signal level and DC bias for measurements

Command Type Description
VOLT {value} command Set AC test signal voltage level
Details
Parameters
  • value (numeric) — AC voltage in Vrms (0.005 to 2.0) or MIN|MAX
Example VOLT 1.0
VOLT? query Query AC test signal voltage level
Details
Returns (numeric)
Example: +1.00000000E+00
CURR {value} command Set AC test signal current level (constant current mode)
Details
Parameters
  • value (numeric) — AC current in Arms (50e-6 to 20e-3) or MIN|MAX
Example CURR 1E-3
CURR? query Query AC test signal current level
Details
Returns (numeric)
Example: +1.00000000E-03
VOLT:RANG:AUTO {state} command Enable/disable automatic signal level ranging
Details
Parameters
  • state (enum) Values: ON, OFF
VOLT:RANG:AUTO? query Query automatic signal level ranging state
Details
Returns (string)
Example: 1
BIAS:VOLT {value} command Set DC bias voltage
Details
Parameters
  • value (numeric) — DC bias voltage in volts (0 to 40 with option 001, 0 to 2 standard) or MIN|MAX
Example BIAS:VOLT 5.0
Note: Standard unit supports 0 to 2V internal DC bias. Option 001 extends to 40V.
BIAS:VOLT? query Query DC bias voltage setting
Details
Returns (numeric)
Example: +0.00000000E+00
BIAS:VOLT:STAT {state} command Enable/disable DC bias voltage output
Details
Parameters
  • state (enum) Values: ON, OFF
BIAS:VOLT:STAT? query Query DC bias voltage output state
Details
Returns (string)
Example: 0
BIAS:CURR {value} command Set DC bias current
Details
Parameters
  • value (numeric) — DC bias current in amps (0 to 0.1) or MIN|MAX
Note: Requires option 001 for extended bias
BIAS:CURR? query Query DC bias current setting
Details
Returns (numeric)
Example: +0.00000000E+00
LIST:VOLT {v1},{v2},... command Set list of AC voltage levels for list sweep mode
Details
Parameters
  • v1,v2,... (numeric_list) — Comma-separated voltage values in Vrms
Example LIST:VOLT 0.1,0.5,1.0
LIST:VOLT? query Query list sweep voltage points
Details
Returns (string) — Comma-separated voltage values
LIST:BIAS:VOLT {v1},{v2},... command Set list of DC bias voltages for list sweep mode
Details
Parameters
  • v1,v2,... (numeric_list) — Comma-separated DC bias voltage values
LIST:BIAS:VOLT? query Query list sweep DC bias voltage points
Details
Returns (string) — Comma-separated DC bias voltage values

Trigger

Section titled “Trigger”

Trigger system configuration and measurement initiation

Command Type Description
TRIG:SOUR {source} command Set trigger source
Details
Parameters
  • source (enum) — INT=internal/continuous, EXT=external BNC, BUS=*TRG/GET, HOLD=manual/software only Values: INT, EXT, BUS, HOLD
TRIG:SOUR? query Query trigger source
Details
Returns (string)
Example: INT
TRIG:DEL {seconds} command Set trigger delay time
Details
Parameters
  • seconds (numeric) — Delay in seconds (0 to 60) or MIN|MAX
TRIG:DEL? query Query trigger delay time
Details
Returns (numeric)
Example: +0.00000000E+00
TRIG:DEL:AUTO {state} command Enable/disable automatic trigger delay
Details
Parameters
  • state (enum) Values: ON, OFF
TRIG:DEL:AUTO? query Query automatic trigger delay state
Details
Returns (string)
Example: 1
INIT command Place instrument in wait-for-trigger state and initiate trigger system
Details
Note: Required before *TRG when trigger source is BUS
INIT:CONT {state} command Enable/disable continuous initiation mode
Details
Parameters
  • state (enum) Values: ON, OFF
Note: When ON, instrument re-arms trigger automatically after each measurement
INIT:CONT? query Query continuous initiation state
Details
Returns (string)
Example: 0
FETCH? query Return the most recent measurement result without triggering a new measurement
Details
Returns (string) — Primary value, secondary value, status code
Example: +1.00540000E-09,+1.23400000E-02,+0
Note: Returns three comma-separated values: primary parameter, secondary parameter, and measurement status (0=normal, +1=overload)
ABORT command Abort a measurement in progress and return trigger system to idle

Correction (Compensation)

Section titled “Correction (Compensation)”

Open, short, and load correction to remove fixture/cable parasitic errors from measurements

Command Type Description
CORR:OPEN command Perform open correction measurement at all frequencies
Details
Note: Leave the test fixture terminals open (no DUT connected). Takes several seconds as it sweeps all preset frequencies.
CORR:OPEN:STAT {state} command Enable/disable open correction
Details
Parameters
  • state (enum) Values: ON, OFF
CORR:OPEN:STAT? query Query open correction state
Details
Returns (string)
Example: 0
CORR:SHOR command Perform short correction measurement at all frequencies
Details
Note: Short the test fixture terminals together (use a shorting bar). Takes several seconds.
CORR:SHOR:STAT {state} command Enable/disable short correction
Details
Parameters
  • state (enum) Values: ON, OFF
CORR:SHOR:STAT? query Query short correction state
Details
Returns (string)
Example: 0
CORR:LOAD {reference_primary},{reference_secondary} command Perform load correction using known reference standard values
Details
Parameters
  • reference_primary (numeric) — Known primary parameter value of reference standard
  • reference_secondary (numeric) — Known secondary parameter value of reference standard
Note: Connect a calibrated reference standard to the fixture. The instrument measures it and computes load correction coefficients.
CORR:LOAD:STAT {state} command Enable/disable load correction
Details
Parameters
  • state (enum) Values: ON, OFF
CORR:LOAD:STAT? query Query load correction state
Details
Returns (string)
Example: 0
CORR:LENG {length} command Set cable length for cable length correction
Details
Parameters
  • length (numeric) — Cable length in meters (0, 1, 2, or 4)
Note: Compensates for phase shift introduced by test cables. Set to 0 for direct connection.
CORR:LENG? query Query cable length correction setting
Details
Returns (numeric)
Example: +0

Averaging and Aperture

Section titled “Averaging and Aperture”

Control measurement speed and averaging for noise reduction

Command Type Description
APER {mode}[,{count}] command Set measurement aperture (integration time) and averaging count
Details
Parameters
  • mode (enum) — SHOR=fastest (~5.6ms), MED=moderate (~19ms), LONG=most accurate (~76ms) Values: SHOR, MED, LONG
  • count (numeric, optional) — Number of measurements to average (1 to 256) Default: 1
Example APER MED,8
Note: Total measurement time = aperture_time x averaging_count. LONG with high averaging gives best accuracy but slowest speed.
APER? query Query aperture mode and averaging count
Details
Returns (string)
Example: MED,1

Data Format

Section titled “Data Format”

Control the format of returned measurement data

Command Type Description
FORM:DATA {format} command Set data transfer format
Details
Parameters
  • format (enum) — ASC=ASCII text, REAL/REAL32=IEEE 754 binary 64/32-bit Values: ASC, REAL, REAL32
Note: ASCII format returns human-readable numbers. Binary formats are faster for bulk data transfer but require binary parsing.
FORM:DATA? query Query data transfer format
Details
Returns (string)
Example: ASC

List Sweep

Section titled “List Sweep”

Configure and execute list-based parameter sweeps

Command Type Description
LIST:MODE {mode} command Set list sweep mode
Details
Parameters
  • mode (enum) — SEQ=sweep through all points on single trigger, STEP=advance one point per trigger Values: SEQ, STEP
LIST:MODE? query Query list sweep mode
Details
Returns (string)
Example: SEQ
LIST:BAND {bw1},{bw2},... command Set measurement aperture for each list sweep point
Details
Parameters
  • bw1,bw2,... (string_list) — Comma-separated aperture values (1-5, corresponding to different integration times)
LIST:BAND? query Query list sweep aperture settings
Details
Returns (string)

System

Section titled “System”

System configuration, display control, and error handling

Command Type Description
SYST:ERR? query Read and remove one error from error queue
Details
Returns (string) — Error code and message
Example: +0,"No error"
DISP:PAGE {page} command Select front panel display page
Details
Parameters
  • page (enum) — MEAS=measurement display, LIST=list sweep setup, CORR=correction setup, SELF=self test Values: MEAS, LIST, CORR, SELF
DISP:PAGE? query Query current display page
Details
Returns (string)
Example: MEAS
DISP:LINE "{message}" command Display custom message on the auxiliary display line
Details
Parameters
  • message (string) — Text message to display
Example DISP:LINE "CAL IN PROGRESS"
SYST:BEEP command Issue a single beep
SYST:BEEP:STAT {state} command Enable/disable beeper
Details
Parameters
  • state (enum) Values: ON, OFF
SYST:BEEP:STAT? query Query beeper state
Details
Returns (string)
Example: 1
SYST:LFR {frequency} command Set power line frequency for line rejection
Details
Parameters
  • frequency (enum) — Power line frequency in Hz Values: 50, 60
SYST:LFR? query Query power line frequency setting
Details
Returns (numeric)
Example: +60

Common Workflows

Section titled “Common Workflows”

Measure Capacitor at 1 kHz

Section titled “Measure Capacitor at 1 kHz”

Measure a capacitor using the parallel capacitance + dissipation factor model at 1 kHz with 1 Vrms signal

1

Reset to known state

*RST
2

Clear status registers

*CLS
3

Select Cp-D measurement function

FUNC:IMP CPD
4

Set test frequency to 1 kHz

FREQ 1E3
5

Set AC signal level to 1 Vrms

VOLT 1.0
6

Set medium aperture with 4x averaging for good accuracy

APER MED,4
7

Set trigger source to BUS

TRIG:SOUR BUS
8

Initiate trigger system

INIT
9

Send bus trigger

*TRG
10

Read measurement (Cp in farads, D unitless, status)

FETCH?
Expected: +1.00540000E-09,+1.23400000E-02,+0

Open/Short Compensation

Section titled “Open/Short Compensation”

Perform open and short correction to remove fixture parasitics before measurement

1

Reset to known state

*RST
2

Clear status registers

*CLS
3

Set desired measurement function

FUNC:IMP CPD
4

Set desired test frequency

FREQ 1E3
5

Ensure fixture terminals are OPEN (no DUT), then execute open correction

CORR:OPEN
Wait for completion — takes several seconds as it measures at multiple frequencies
6

Wait for open correction to complete

*OPC?
Expected: 1
7

Enable open correction

CORR:OPEN:STAT ON
8

SHORT fixture terminals (use shorting bar), then execute short correction

CORR:SHOR
Wait for completion
9

Wait for short correction to complete

*OPC?
Expected: 1
10

Enable short correction

CORR:SHOR:STAT ON
11

Connect DUT and trigger measurement

TRIG:SOUR BUS
12

Initiate and trigger

INIT
13

Send bus trigger

*TRG
14

Read compensated measurement

FETCH?
Expected: +X.XXXXXXXXE+XX,+X.XXXXXXXXE+XX,+0

Frequency Sweep via List Mode

Section titled “Frequency Sweep via List Mode”

Sweep measurement across multiple frequencies using list mode to characterize impedance vs frequency

1

Reset to known state

*RST
2

Clear status registers

*CLS
3

Select impedance magnitude + phase function

FUNC:IMP ZTD
4

Set AC signal level to 1 Vrms

VOLT 1.0
5

Set list sweep frequencies (logarithmic spread)

LIST:FREQ 100,1E3,10E3,100E3,1E6
6

Set sequential sweep mode (all points per trigger)

LIST:MODE SEQ
7

Set trigger source to BUS

TRIG:SOUR BUS
8

Switch display to list view

DISP:PAGE LIST
9

Initiate trigger system

INIT
10

Send bus trigger to start sweep

*TRG
11

Wait for sweep completion

*OPC?
Expected: 1
12

Read sweep results (|Z|, theta pairs at each frequency)

FETCH?
Expected: Comma-separated |Z|,theta,status triplets for each frequency point