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Hewlett-Packard E3631A

Hewlett-Packard

E3631A

80W triple-output DC power supply (6V/5A, +25V/1A, -25V/1A)

power_supply SCPI
HP E3631A triple output DC power supply front panel
eBay listing photo
Default Address 5
Termination LF
IEEE 488.2 Yes
IDN Patterns
HEWLETT-PACKARD,E3631A,*,*AGILENT TECHNOLOGIES,E3631A,*,*
Documentation

The E3631A is a widely-used benchtop triple-output power supply produced from the late 1990s. It provides three isolated outputs: 6V/5A (30W), +25V/1A (25W), and -25V/1A (25W) for a total of 80W. The P25V and N25V outputs share a common return terminal and can be configured for tracking mode to provide symmetric bipolar supplies. All three outputs are controlled by a single output enable relay. GPIB (standard) and RS-232 interfaces are included. Superseded by the E36300 series.

Status Byte

Section titled “Status Byte”
Bit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
OperationRQS/MSSESBMAVQuestionable DataError QueueUnusedUnused
Operation condition summary bitRequesting service / Master summary statusEvent status byte summary bitMessage available in output bufferQuestionable condition summary bitOne or more errors in error queueNot usedNot used

Use *STB? to read status byte, *SRE to set service request enable register

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,E3631A,0,1.7-5.0-1.0
*RST command Reset to factory default state. All outputs set to 0V/0A, output disabled, P6V selected.
*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, 1 for fail
Details
Returns (numeric)
Example: 0
Note: Takes several seconds to complete. Output is disabled during self-test.
*TRG command Trigger output change from bus (requires trigger source BUS)
*WAI command Wait until all pending operations complete before executing next command
*SAV {location} command Save present state to non-volatile memory location
Details
Parameters
  • location (numeric) — Memory location 1, 2, or 3 Values: 1, 2, 3
*RCL {location} command Recall saved state from non-volatile memory location
Details
Parameters
  • location (numeric) — Memory location 1, 2, or 3 Values: 1, 2, 3
Note: Restores voltage, current, output state, and selected output for all three channels.

Output Control

Section titled “Output Control”

Select outputs and set voltage/current levels

Command Type Description
INST {output} command Select active output for subsequent voltage/current commands
Details
Parameters
  • output (enum) — Output channel name Values: P6V, P25V, N25V
Example INST P25V
INST? query Query currently selected output
Details
Returns (string)
Example: P6V
INST:NSEL {number} command Select active output by numeric index
Details
Parameters
  • number (numeric) — 1=P6V, 2=P25V, 3=N25V Values: 1, 2, 3
INST:NSEL? query Query currently selected output as numeric index
Details
Returns (numeric)
Example: 1
VOLT {value} command Set voltage level on currently selected output
Details
Parameters
  • value (numeric) — Voltage in volts, or MIN|MAX|UP|DOWN
Example VOLT 3.3
Note: Range depends on selected output. UP/DOWN step by VOLT:STEP increment.
VOLT? query Query programmed voltage on currently selected output
Details
Returns (numeric) — Voltage setpoint in volts
Example: +3.300000E+00
VOLT? MIN query Query minimum programmable voltage on currently selected output
Details
Returns (numeric)
Example: +0.000000E+00
VOLT? MAX query Query maximum programmable voltage on currently selected output
Details
Returns (numeric)
Example: +6.180000E+00
VOLT:STEP {value} command Set voltage step size for VOLT UP/DOWN commands
Details
Parameters
  • value (numeric) — Step size in volts, or DEF
Note: Default step is the minimum resolution of the selected output.
VOLT:STEP? query Query current voltage step size
Details
Returns (numeric)
Example: +1.000000E-03
CURR {value} command Set current limit on currently selected output
Details
Parameters
  • value (numeric) — Current in amps, or MIN|MAX|UP|DOWN
Example CURR 1.5
Note: Range depends on selected output. UP/DOWN step by CURR:STEP increment.
CURR? query Query programmed current limit on currently selected output
Details
Returns (numeric) — Current setpoint in amps
Example: +1.500000E+00
CURR? MIN query Query minimum programmable current on currently selected output
Details
Returns (numeric)
Example: +0.000000E+00
CURR? MAX query Query maximum programmable current on currently selected output
Details
Returns (numeric)
Example: +5.150000E+00
CURR:STEP {value} command Set current step size for CURR UP/DOWN commands
Details
Parameters
  • value (numeric) — Step size in amps, or DEF
CURR:STEP? query Query current step size
Details
Returns (numeric)
Example: +1.000000E-03
OUTP {state} command Enable or disable all three outputs simultaneously
Details
Parameters
  • state (enum) Values: ON, OFF
Note: There is only one output enable for all three channels. Individual channels cannot be enabled/disabled separately.
OUTP? query Query output state
Details
Returns (numeric) — 0=OFF, 1=ON
Example: 0

Measurement

Section titled “Measurement”

Read back actual output voltage and current

Command Type Description
MEAS:VOLT? query Measure actual voltage on currently selected output
Details
Returns (numeric) — Measured voltage in volts
Example: +3.298000E+00
MEAS:VOLT? {output} query Measure actual voltage on specified output without changing the selection
Details
Parameters
  • output (enum) — Output channel name Values: P6V, P25V, N25V
Returns (numeric) — Measured voltage in volts
Example: +5.021000E+00
Example MEAS:VOLT? P6V
MEAS:CURR? query Measure actual current on currently selected output
Details
Returns (numeric) — Measured current in amps
Example: +1.234000E-01
MEAS:CURR? {output} query Measure actual current on specified output without changing the selection
Details
Parameters
  • output (enum) — Output channel name Values: P6V, P25V, N25V
Returns (numeric) — Measured current in amps
Example: +5.000000E-02
Example MEAS:CURR? P25V

Output Configuration (APPL)

Section titled “Output Configuration (APPL)”

Combined commands to set output, voltage, and current in a single command

Command Type Description
APPL {output},{voltage},{current} command Select output and set voltage and current in one command
Details
Parameters
  • output (enum) — Output channel name Values: P6V, P25V, N25V
  • voltage (numeric) — Voltage in volts, or DEF|MIN|MAX
  • current (numeric) — Current in amps, or DEF|MIN|MAX
Example APPL P6V,3.3,2.0
Note: This is the most efficient way to configure an output. Equivalent to INST + VOLT + CURR.
APPL? {output} query Query voltage and current settings for specified output
Details
Parameters
  • output (enum) — Output channel name Values: P6V, P25V, N25V
Returns (string) — Quoted voltage and current pair
Example: "3.300000,2.000000"
Example APPL? P6V
APPL? query Query voltage and current settings for currently selected output
Details
Returns (string)
Example: "3.300000,2.000000"
VOLT:RANG? query Query voltage range of currently selected output
Details
Returns (string) — P6V, P25V, or N25V range identifier
Example: P6V
Note: Returns the range name corresponding to the currently selected output.

Overvoltage Protection

Section titled “Overvoltage Protection”

Overvoltage protection (OVP) configuration and control

Command Type Description
VOLT:PROT {value} command Set overvoltage protection level on currently selected output
Details
Parameters
  • value (numeric) — OVP level in volts, or MIN|MAX
Example VOLT:PROT 7.0
Note: When output voltage exceeds this level, output is disabled and the OVP condition is latched. P6V: 1-7.5V, P25V: 1-27.5V, N25V: 1-27.5V.
VOLT:PROT? query Query overvoltage protection level on currently selected output
Details
Returns (numeric)
Example: +7.000000E+00
VOLT:PROT:STAT {state} command Enable or disable overvoltage protection on currently selected output
Details
Parameters
  • state (enum) Values: ON, OFF
VOLT:PROT:STAT? query Query overvoltage protection enabled state
Details
Returns (numeric) — 0=OFF, 1=ON
Example: 1
VOLT:PROT:CLE command Clear a latched OVP condition on currently selected output
Details
Note: After clearing, you must reduce the voltage below the OVP level before re-enabling the output.
VOLT:PROT:TRIP? query Query whether OVP has tripped on currently selected output
Details
Returns (numeric) — 0=not tripped, 1=tripped
Example: 0
CURR:PROT:STAT {state} command Enable or disable overcurrent protection (OCP) on currently selected output
Details
Parameters
  • state (enum) Values: ON, OFF
Note: When OCP is enabled, output disables if it enters constant-current mode.
CURR:PROT:STAT? query Query overcurrent protection enabled state
Details
Returns (numeric) — 0=OFF, 1=ON
Example: 0
CURR:PROT:CLE command Clear a latched OCP condition on currently selected output
CURR:PROT:TRIP? query Query whether OCP has tripped on currently selected output
Details
Returns (numeric) — 0=not tripped, 1=tripped
Example: 0

Trigger

Section titled “Trigger”

Trigger system for deferred output changes

Command Type Description
TRIG:SOUR {source} command Set trigger source for output changes
Details
Parameters
  • source (enum) — BUS=*TRG or Group Execute Trigger, IMM=immediate on INIT Values: BUS, IMM
TRIG:SOUR? query
Details
Returns (string)
Example: BUS
TRIG:DEL {seconds} command Set delay between trigger and output change
Details
Parameters
  • seconds (numeric) — Delay in seconds (0 to 3600) or MIN|MAX
TRIG:DEL? query
Details
Returns (numeric)
Example: +0.000000E+00
VOLT:TRIG {value} command Set pending triggered voltage level on currently selected output
Details
Parameters
  • value (numeric) — Voltage in volts, or MIN|MAX
Note: This value is applied when a trigger is received after INIT.
VOLT:TRIG? query Query pending triggered voltage level
Details
Returns (numeric)
Example: +5.000000E+00
CURR:TRIG {value} command Set pending triggered current level on currently selected output
Details
Parameters
  • value (numeric) — Current in amps, or MIN|MAX
Note: This value is applied when a trigger is received after INIT.
CURR:TRIG? query Query pending triggered current level
Details
Returns (numeric)
Example: +1.000000E+00
INIT command Enable trigger system -- supply enters wait-for-trigger state
Details
Note: After INIT, the supply waits for a trigger event to apply VOLT:TRIG and CURR:TRIG values.

System

Section titled “System”

System configuration, errors, and display control

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"
Note: Error queue holds up to 20 errors. Errors are returned FIFO.
SYST:VERS? query Query SCPI version compliance
Details
Returns (string)
Example: 1995.0
DISP {state} command Turn front panel display on/off
Details
Parameters
  • state (enum) Values: ON, OFF
Note: Display turns back on automatically when returning to local mode.
DISP? query Query display state
Details
Returns (numeric) — 0=OFF, 1=ON
Example: 1
DISP:TEXT "{message}" command Display custom text on front panel (up to 11 characters)
Details
Parameters
  • message (string) — Up to 11 characters
Example DISP:TEXT "TESTING"
DISP:TEXT:CLE command Clear custom display text and return to normal display
SYST:BEEP command Issue a single beep
SYST:LOC command Place instrument in local mode (front panel enabled)
Details
Note: Equivalent to IEEE-488 Go To Local (GTL) command.
SYST:REM command Place instrument in remote mode (front panel locked out)
Details
Note: Equivalent to IEEE-488 Remote Enable (REN) assertion.
SYST:RWL command Place instrument in remote mode with local lockout
Details
Note: Front panel LOCAL key is also disabled. Use SYST:LOC to return to local.
OUTP:TRAC {state} command Enable or disable tracking mode for P25V and N25V outputs
Details
Parameters
  • state (enum) Values: ON, OFF
Note: When tracking is enabled, P25V and N25V maintain equal and opposite voltages. Setting voltage on P25V automatically mirrors to N25V.
OUTP:TRAC? query Query tracking mode state
Details
Returns (numeric) — 0=OFF, 1=ON
Example: 0

Calibration

Section titled “Calibration”

Calibration commands (require secure code)

Command Type Description
CAL:SEC:STAT {state},{code} command Enable or disable calibration mode with security code
Details
Parameters
  • state (enum) Values: ON, OFF
  • code (string) — Calibration security code (factory default is blank)
Note: Calibration requires physical access. See service manual for full calibration procedure.
CAL:COUN? query Query number of times the instrument has been calibrated
Details
Returns (numeric)
Example: 52
CAL:STR? query Query calibration message string (typically contains last cal date)
Details
Returns (string)
Example: "CAL 2024-01-15"

Status Subsystem

Section titled “Status Subsystem”

Questionable and operation status register control

Command Type Description
STAT:QUES? query Read and clear questionable status event register
Details
Returns (numeric) — Bit 0=P6V in CV/CC, bit 1=P25V in CV/CC, bit 9=N25V in CV/CC, bit 10=unregulated, bit 11=OVP tripped, bit 12=OCP tripped
Example: 0
STAT:QUES:ENAB {mask} command Set questionable status enable register
Details
Parameters
  • mask (numeric) — Bitmask 0-32767
STAT:QUES:ENAB? query Query questionable status enable register
Details
Returns (numeric)
Example: 0
STAT:QUES:COND? query Read questionable status condition register (not latched, real-time)
Details
Returns (numeric) — Same bit mapping as STAT:QUES? but reflects current conditions
Example: 0
STAT:OPER? query Read and clear operation status event register
Details
Returns (numeric) — Bit 5=wait-for-trigger, bit 8=CV on P6V, bit 9=CV on P25V, bit 10=CV on N25V
Example: 0
STAT:OPER:ENAB {mask} command Set operation status enable register
Details
Parameters
  • mask (numeric) — Bitmask 0-32767
STAT:OPER:ENAB? query Query operation status enable register
Details
Returns (numeric)
Example: 0
STAT:OPER:COND? query Read operation status condition register (not latched, real-time)
Details
Returns (numeric) — Same bit mapping as STAT:OPER? but reflects current conditions
Example: 0
STAT:PRES command Preset all enable registers to zero

Common Workflows

Section titled “Common Workflows”

Set Output Voltage

Section titled “Set Output Voltage”

Configure a single output with voltage and current limit, enable, and verify

1

Reset to known state

*RST
2

Clear status registers

*CLS
3

Select P6V output and set 3.3V at 1A limit

APPL P6V,3.3,1.0
4

Enable output

OUTP ON
5

Wait for output to settle

*OPC?
Expected: 1
6

Verify actual voltage

MEAS:VOLT? P6V
Expected: +3.29XXXXX+00
7

Verify actual current

MEAS:CURR? P6V
Expected: Load-dependent value

Monitor All Outputs

Section titled “Monitor All Outputs”

Read actual voltage and current on all three outputs

1

Measure P6V voltage

MEAS:VOLT? P6V
Expected: +X.XXXXXXE+XX
2

Measure P6V current

MEAS:CURR? P6V
Expected: +X.XXXXXXE+XX
3

Measure P25V voltage

MEAS:VOLT? P25V
Expected: +X.XXXXXXE+XX
4

Measure P25V current

MEAS:CURR? P25V
Expected: +X.XXXXXXE+XX
5

Measure N25V voltage

MEAS:VOLT? N25V
Expected: -X.XXXXXXE+XX
6

Measure N25V current

MEAS:CURR? N25V
Expected: +X.XXXXXXE+XX

OVP Test

Section titled “OVP Test”

Set overvoltage protection, ramp voltage above threshold, verify trip

1

Reset to known state

*RST
2

Select P6V output

INST P6V
3

Set OVP level to 5.5V

VOLT:PROT 5.5
4

Enable OVP

VOLT:PROT:STAT ON
5

Set voltage below OVP

VOLT 5.0
6

Set current limit

CURR 1.0
7

Enable output

OUTP ON
8

Verify output is on and voltage is correct

MEAS:VOLT?
Expected: +5.0XXXXE+00
9

Raise voltage above OVP threshold

VOLT 5.6
10

Check if OVP has tripped

VOLT:PROT:TRIP?
Expected: 1
11

Output should now be disabled

OUTP?
Expected: 0
12

Lower voltage below OVP level

VOLT 3.0
13

Clear the OVP trip latch

VOLT:PROT:CLE
14

Re-enable output

OUTP ON

Symmetric Tracking Supply

Section titled “Symmetric Tracking Supply”

Configure P25V and N25V as a symmetric bipolar supply using tracking mode

1

Reset to known state

*RST
2

Enable tracking mode

OUTP:TRAC ON
3

Set P25V to 12V (N25V automatically mirrors to -12V)

APPL P25V,12.0,0.5
4

Enable output

OUTP ON
5

Verify positive rail

MEAS:VOLT? P25V
Expected: +1.20XXXXX+01
6

Verify negative rail tracks

MEAS:VOLT? N25V
Expected: -1.20XXXXX+01

Triggered Output Change

Section titled “Triggered Output Change”

Pre-program a voltage change and apply it with a bus trigger

1

Reset to known state

*RST
2

Set initial voltage on P6V

APPL P6V,3.3,2.0
3

Enable output

OUTP ON
4

Select bus trigger source

TRIG:SOUR BUS
5

Set triggered voltage to 5.0V

INST P6V
6

Program pending voltage level

VOLT:TRIG 5.0
7

Enable trigger system

INIT
8

Send trigger to apply the change

*TRG
9

Verify voltage changed

MEAS:VOLT? P6V
Expected: +5.0XXXXE+00