DMM — Multimeter¶

Auto-generated reference

For the definitive command list extracted directly from source code, see REPL Command Reference.

Controls digital multimeters.

Multiple DMMs are named dmm1, dmm2, etc.
Typical workflow: configure mode → take readings → store results
Or use dmm meas for a one-shot measurement without a separate configure step

HP 34401AKeysight EDU34450AOWON XDM1041

6½-digit multimeter with GPIB interface. Supports NPLC control, display text, fetch, and high-accuracy measurements.

5½-digit multimeter with USB/LAN interface. Supports capacitance, temperature, dual display, and resolution speed control (SLOW/MEDIUM/FAST). Does not support NPLC.

4½-digit multimeter with USB/serial interface. Supports basic DMM commands.

dmm config¶

Configure the measurement mode. The mode stays active until changed.

dmm config <mode> [range] [resolution] [nplc=<n>]
dmm mode <mode> [range] [resolution] [nplc=<n>]

Note

dmm mode is an alias for dmm config — both are identical.

Parameter	Required	Values	Description
`mode`	required	see below	What to measure.
`range`	optional	float, `DEF`, `MIN`, `MAX`	Measurement range (e.g. `10` for 10 V range). `DEF` = auto-range.
`resolution`	optional	float, `DEF`, `MIN`, `MAX`	Resolution (number of significant digits). `DEF` = default.
`nplc=`	optional	`0.02`, `0.2`, `1`, `10`, `100`	Integration time in power line cycles. Higher = slower but lower noise. HP 34401A only, DC modes only.

Measurement modes:

Mode	Measures
`vdc`	DC voltage
`vac`	AC voltage (RMS)
`idc`	DC current
`iac`	AC current (RMS)
`res`	Resistance, 2-wire
`fres`	Resistance, 4-wire (Kelvin)
`freq`	Frequency
`per`	Period
`cont`	Continuity
`diode`	Diode forward voltage
`cap`	Capacitance (device-dependent)
`temp`	Temperature (device-dependent)

dmm config vdc                    # DC voltage, auto-range
dmm config vdc 10                 # DC voltage, 10 V range
dmm config vdc 10 DEF nplc=10    # high-accuracy DC voltage (slow)
dmm config res                    # 2-wire resistance, auto-range
dmm config fres DEF DEF nplc=1   # 4-wire resistance, 1 PLC
dmm config freq                   # frequency measurement

Tip

For a single quick reading, use dmm meas instead — it configures and reads in one step.

dmm read¶

Take a reading using the currently configured mode.

dmm read

Call dmm config first to set the mode. dmm read does not store the result — use the assignment syntax (label = dmm meas unit=V) to record it.

dmm config vdc
dmm read       # take one DC voltage reading

dmm meas¶

One-shot measurement — configure and read in a single command.

dmm meas <mode> [range] [resolution]

Parameter	Required	Values	Description
`mode`	required	same as `dmm config`	Measurement mode.
`range`	optional	float or `DEF`	Measurement range. Default: auto-range.
`resolution`	optional	float or `DEF`	Resolution. Default: default.

dmm meas vdc        # quick DC voltage reading
dmm meas res        # quick resistance reading
dmm meas freq       # quick frequency reading

Note

dmm meas does not support nplc= or storing results. For high-accuracy or repeated measurements, use dmm config + dmm read or the assignment syntax (label = dmm meas unit=V).

Recording measurements

Use assignment syntax to measure and store the result to the measurement log in one step:

<label> = dmm meas [scale=<factor>] [unit=<str>]

Parameter	Required	Values	Description
`label`	required	string, no spaces	Name for this entry in the log. Appears as the row identifier in `log print` output. Also used as the dictionary key in `calc` expressions: `m["label"]`. Use underscores instead of spaces — e.g. `vout_mv`.
`scale=`	optional	float	Multiply the raw reading by this factor before storing. Useful for unit conversion — e.g. `scale=1000` to convert V → mV, or `scale=0.001` to convert mA → A. Default: `1.0` (no scaling).
`unit=`	optional	string	Unit label shown in `log print` output (e.g. `V`, `mV`, `A`, `Ω`). Display-only — does not affect the stored value or calculations.

Requires dmm config first

Call dmm config <mode> before using the assignment syntax. The DMM must be in the correct mode.

dmm config vdc
vout = dmm meas unit=V                  # store as 'vout', access as m["vout"]

dmm config res
r_load = dmm meas unit=Ω               # store resistance

dmm config vdc
vout_mv = dmm meas scale=1000 unit=mV  # convert V → mV before storing

Using stored values in calculations:

dmm config vdc
voltage = dmm meas unit=V

dmm config idc
current = dmm meas unit=A

calc power m["voltage"] * m["current"] unit=W    # compute power
log print

See Log & Calc for full details.

dmm fetch¶

Fetch the last reading without triggering a new measurement.

dmm fetch

Returns the most recent measurement result without re-triggering. HP 34401A only.

dmm beep¶

Trigger an audible beep from the DMM.

dmm beep

Useful as audio confirmation during scripted tests — e.g. beep when a measurement is complete.

dmm display¶

Control the front panel display.

dmm display <on|off>

Parameter	Required	Values	Description
`on\\|off`	required	`on`, `off`	Turn the display on or off.

dmm display off    # blank the display (speeds up measurements on HP 34401A)
dmm display on     # restore display

dmm text¶

Show custom text on the DMM display.

dmm text <message> [scroll=<auto|on|off>] [delay=<s>] [loops=<n>] [pad=<n>] [width=<n>]

Parameter	Required	Values	Description
`message`	required	string	Text to show on the front panel.
`scroll=`	optional	`auto`, `on`, `off`	Scroll behavior for messages wider than the display. `auto` = scroll only if too wide.
`delay=`	optional	float (s)	Delay between scroll steps in seconds.
`loops=`	optional	int	Number of times to repeat the scroll animation.

dmm text READY
dmm text TESTING scroll=auto delay=0.2

Note

HP 34401A only.

dmm text_loop¶

Scroll text continuously across the DMM display in a background loop. Use this for long messages that don't fit on the 12-character display, or for unattended display status — contrast with dmm text which sets a static one-shot message.

Start scrolling¶

dmm text_loop <message> [delay=<s>] [pad=<n>] [width=<n>]

Parameter	Required	Values	Description
`message`	required	string	Text to scroll.
`delay=`	optional	float (s)	Seconds between scroll steps. Default: `0.2`.
`pad=`	optional	int	Blank characters to pad each side of the message. Default: `4` (the HP 34401A display is 12 characters wide).
`width=`	optional	int	Display window width in characters. Default: `12`.

Stop scrolling¶

dmm text_loop off

Stops the scrolling loop and clears the display.

dmm text_loop TESTING delay=0.15    # start scrolling
dmm text_loop off                   # stop

Note

HP 34401A only. The loop runs until dmm text_loop off is called or the REPL exits.

Edge cases

Calling dmm text_loop while a loop is already running replaces the existing loop immediately.
Empty messages scroll blank padding across the display.
If pad + message length > width, the message wraps naturally as the scroll window advances.

dmm cleartext¶

Clear any custom text from the DMM display and restore the measurement display.

dmm cleartext

Clears text set by either dmm text or dmm text_loop. If a scrolling loop is active, stop it first with dmm text_loop off before calling dmm cleartext. Calling dmm cleartext when no custom text is displayed is a no-op.

Note

HP 34401A only. See also: dmm text, dmm text_loop.

dmm ranges¶

Print the valid measurement ranges for the connected DMM model.

dmm ranges

Note

dmm limits is an alias for dmm ranges.

dmm state¶

dmm state <safe|reset>

Value	Effect
`safe`	Returns to safe defaults
`reset`	`*RST` — factory defaults