OHAUS PX124 Manual, Explained: Setup, Keys, Modes, Menus and Calibration

By MNM Scales · Last updated November 2, 2026

The OHAUS PX124 is the 120 g x 0.1 mg Pioneer PX analytical balance with internal calibration (OHAUS item 30429838), a glass draft shield and RS232 and USB ports. OHAUS writes one instruction manual for the whole Pioneer PX family, from 82 g analytical models to 12 kg precision balances, InCal and ExCal versions alike. This guide pulls out only what applies to the PX124, in the order you will need it, with the menu names as they appear on the display.

OHAUS PX124 manual at a glance: specifications

Item	OHAUS PX124 (InCal)
Capacity	120 g
Readability	0.1 mg (0.0001 g)
Repeatability (sd)	0.08 mg up to 5% of full load; 0.1 mg to full range
Linearity deviation	±0.2 mg (typical ±0.06 mg)
Stabilization time	3 seconds typical
Sensitivity temperature drift	±2 ppm/K
Typical minimum weight (USP, k=2, U=0.10%)	160 mg
Calibration	InCal internal calibration; span calibration points 50 g and 100 g; linearity points 0, 50 g and 100 g
Weighing units	19, including g, mg, kg, ct, oz, ozt, dwt, grain, lb, newton, tael, tola and 1 custom unit
Application modes	Weighing, parts counting, percent weighing, dynamic weighing, density determination, formulation
Pan	90 mm diameter, stainless steel, inside a glass draft shield
Interfaces	RS232 (DB9) and USB device
Power	AC adapter (included): 100-240 V in, 12 V DC 0.5 A out
Operating temperature	10 to 30 °C (50 to 86 °F)
Size and weight	209 x 321 x 309 mm; 4.5 kg (10 lb)

The PX124 and the PX124/E share the same 120 g x 0.1 mg range and the same manual. The PX124 has InCal; the PX124/E calibrates with external weights only, so its Calibration menu shows Span Cal and Linearity Cal. Our internal vs external calibration guide explains when each type makes sense.

Setting up the PX124

1. Unpack. The box holds the balance, the power adapter with its attaching plug, the stainless steel pan and the warranty card. Save the packaging for transport or mail-in service.
2. Choose the spot. A sturdy bench away from heat sources, fast temperature changes, air currents and vibration. Allow enough space around it, as the manual asks.
3. Fit the pan inside the glass draft shield.
4. Level it. Turn the 4 leveling feet until the bubble in the round window beside the display is centered. Re-level every time you move the balance.
5. Power and acclimatise. Plug the adapter into the rear power receptacle, then into the outlet. OHAUS asks for 1.5 hours connected to power before you use a 0.1 mg balance such as the PX124.
6. Connect the interface if you need one. RS232 goes to a PC or printer with a straight-through serial cable; USB goes to a PC only, with a USB Type A to Type B cable (not included). See how to connect a scale to a computer.
7. Calibrate on first install and after every move, as described below. On the PX124, an internal calibration takes one menu selection.

The four keys and what each press does

Each key does one job on a short press, another on a long press (press and hold), and inside the menu it becomes Yes, No, Back or Exit.

Key	Short press	Press and hold	In the menu
On / Zero	Turns the balance on; when on, sets zero	Off	Yes: accepts the blinking setting, or raises a value
Print / Unit	Sends the displayed value to the interface	Changes the weighing unit	No: rejects the blinking setting, or lowers a value
Function / Mode	Action depends on the application	Changes the application mode	Back: returns to the previous menu item or aborts a calibration
Tare / Menu-Cal	Tares the container	Opens the main menu; Calibration is the first sub-menu	Exit: leaves the sub-menu

To weigh, press Zero with the pan empty, place the sample and read the value once the stability * appears. To tare, place the empty container, press Tare, then add the sample. After you remove the container, the display reads negative; press Tare to clear it.

The six application modes

Press and hold Function / Mode to step through the applications. Before any of them, the balance should be level and calibrated.

• Weighing (the default). Turn on Batch Printing in the Print menu to store up to 10 samples and print them together.
• Parts counting. Choose a sample size from 1 to 1,000 (default 10), place the samples and press Function / Mode to set the average piece weight (APW). APW Optimization recalculates the piece weight as you add parts. The minimum piece weight is 0.1d.
• Percent weighing. Store a reference sample as 100%, then read test samples as a percentage. The reference must be at least 100d.
• Dynamic weighing for moving loads such as small animals: set an averaging time from 1 to 15 seconds (default 10), and the balance holds the averaged result.
• Density determination for sinking or floating solids, liquids with a calibrated sinker, and porous materials with oil. The balance has a built-in water density table from 10 °C to 30.9 °C. OHAUS’s density kit 80253384 is sold separately (not included).
• Formulation for recipes and compounding: up to 50 components plus a filler if the recipe needs one, with the total and each component weight on recall.

The PX124 also has a weigh-below hook. Unplug the balance, remove the pan and draft shield parts before turning the balance over, remove the protective cover over the opening, power it back on, and hang the sample on a string or wire.

Menu settings in the OHAUS Pioneer manual

Press and hold Tare / Menu-Cal to open the menu. Press No to step between sub-menus and Yes to enter one. The main sub-menus are:

Sub-menu	What you set
Calibration	Internal Cal, Span Cal, Linearity Cal and InCal Adjust
Setup	Password, language, filter level (low, medium, high), auto zero tracking (off, 0.5d, 1d, 3d), auto tare, graduations, date and time, brightness, auto dim, auto off, capacity bar, Approved Mode
Units	Turn each of the 19 units on or off, and define the custom unit
RS232	Baud rate 1,200 to 38,400; 7 or 8 data bits with parity and stop bits; handshake none, XON/XOFF or hardware
Print	Stable only, numeric only, print to, output format, batch and label printing, auto print, header and the fields that print
GLP	Header lines, balance name, user name and project name for GLP/GMP records
Factory Reset	Resets all menus to factory settings
Lockout	Locks or unlocks individual menus

A password made of the keys 1, 2 and 3 (up to 6 digits) locks the calibration, setup, units, print, GLP, reset and RS232 settings. For a busy lab, a password plus Lockout keeps settings where you left them. If the display drifts or will not settle, raise the filter level first; see scale will not zero or keeps drifting for other causes.

OHAUS Pioneer calibration on the PX124: internal, span and linearity

The PX124 offers three calibration methods. Do not disturb the balance while any of them runs.

1. Internal calibration (InCal). With the balance warmed up, level and the pan empty, press and hold Tare / Menu-Cal and select Internal Cal. The display shows the status; press any key to return when it finishes. No weights are needed.
2. Span calibration. Hold Tare / Menu-Cal, press Yes, press No until Span Cal appears, then Yes. When the display shows Place weights and 100.000 g, place 100 g. Press Function / Mode first if you want to use 50 g instead. Remove the weight when prompted; Calibration done confirms it. The best accuracy comes from the mass closest to full span.
3. Linearity calibration. Select Linearity Cal the same way. The balance captures zero, then asks for 50 g and 100 g in turn, and shows Linearity done.
4. InCal Adjust. After an internal calibration, place a test weight equal to the span value. If the reading is off by more than 1 division, enter the difference in divisions under InCal Adjust, run Internal Cal again and recheck.

Calibration weights are not included. For a 0.1 mg balance, use 50 g and 100 g weights in a class suited to that readability; our calibration weights guide and weight class guide show how to match them, and we sell calibration weights. The manual asks you to verify calibration periodically with an accurate weight; our how often to calibrate guide covers setting an interval.

Approved Mode, security switch and trade use

The manual’s Approved Mode (Setup menu) and the security switch on the back work together for balances used where weights and measures rules apply. With the switch locked and Approved Mode on, only Internal Cal shows in the Calibration menu, the filter and auto tare lock, auto zero tracking is limited to 0.5d or off, graduations are forced to 1 division, and Stable Only printing is forced on. OHAUS notes that the verification and seal must be done by a local weights and measures official or an authorized service agent.

The PX124 is built for laboratory, QC, education and formulation work, with 0.1 mg readability. NCWM’s certificate search (checked November 2, 2026) lists no NTEP certificate for the Pioneer PX series. For buying or selling by weight in the U.S., choose an NTEP-approved model; our NTEP guide and legal for trade jewelry scale guide explain the classes, and we can match one to your use.

Texas note: TDA does not require an NTEP certificate for every device, but the scale must meet NIST Handbook 44 and suit its use; some scales do need one, so we recommend NTEP models and can check yours. See TDA’s scales used in trade guidance (PDF) and our TDA scale certification guide, or call us or TDA to confirm your use.

Not sure your use counts as trade? Our free legal-for-trade scale checker walks through the Texas questions.

Interfaces, printing and accessories

RS232 is a 9-pin female Sub-D connector, full duplex, with a cable length of up to 15 m. USB appears on a PC as a virtual COM port after you install the OHAUS driver. Both ports accept simple commands such as P (print), SP (print on stability), IP (immediate print), T (tare), Z (zero) and PV (software version); over RS232, IC starts an internal calibration. For collecting readings into Excel or Word, OHAUS provides its SPDC software as a download.

• OHAUS RS232 cable, 9-pin (80500525) for a PC or printer (not included).
• USB cable, Type A to Type B (not included).
• Other accessories listed in the manual (not included): SF40A printer, AD7-RS auxiliary display, density kit 80253384, calibrated sinker 83034024, security device 80850043, dust cover and a spare power adapter 46001724.

Care and common messages

Unplug the balance before cleaning and keep liquid out of the interior. Wipe the housing with a lint-free cloth dampened with water or a mild cleaner, and clean the glass with a commercial glass cleaner. OHAUS warns against solvents, harsh chemicals, ammonia and abrasive cleaners.

• Cannot change a menu setting: the sub-menu is locked; unlock it in Lockout, or the menu is hidden because Approved Mode is on.
• Parts counting or percent will not accept the sample: the piece weight is under 0.1d or the reference is under 100d; use more pieces.
• Calibration fails: the environment is not stable or the weights do not match the calibration points; move the balance and use 50 g or 100 g.
• Power-on message: the pan is missing, is not the OHAUS pan, is not seated, or has a load on it; seat the OHAUS pan with nothing on it, then power on again.

For a full care routine, see our analytical balance preventive maintenance checklist. If a message persists, our repair bench can diagnose it.

Calibration, repair and rentals

• Calibrated before it ships: in-house calibration $95 or NIST calibration certificate $395 for balances up to 2.2 kg, including the PX124. See NIST vs in-house certificates.
• Balance calibration in Houston: our TDA-registered technicians calibrate analytical balances in our shop and on site. See balance calibration in Houston and scale calibration in Houston.
• Mail-in calibration: pack the balance in its original packaging and ship it to our shop with the mail-in calibration service.
• Cypress pickup by appointment: drop off or pick up at our Cypress, TX shop (21249 FM 529 Rd, Cypress, TX 77433).
• On-site service: on-site calibration is $295 plus $2 per mile per visit, plus the calibration fee for each balance.
• Repair: load cell, adapter, display and interface problems go to our scale repair bench.
• Rentals: we rent all types of scales; ask about a scale rental while yours is in for service.

Frequently asked questions

Where can I find the OHAUS PX124 manual?

OHAUS publishes it as the Pioneer PX Series instruction manual (Manual_PX) on the Documents tab of its Pioneer Analytical page. One manual covers every PX model, InCal and ExCal.

How do I calibrate the OHAUS PX124?

Press and hold Tare / Menu-Cal and select Internal Cal with the pan empty. For span calibration, select Span Cal and place 100 g (or 50 g) when prompted.

What calibration weight does the PX124 need?

Internal calibration needs no weights. Span calibration uses 100 g or 50 g, and linearity calibration uses 50 g and 100 g. Weights are not included.

How long should the PX124 warm up?

OHAUS asks for 1.5 hours connected to power, in the room where you will use it, before you weigh on a 0.1 mg balance.

What application modes does the PX124 have?

Weighing, parts counting, percent weighing, dynamic weighing, density determination and formulation.

Can the PX124 connect to a computer?

Yes. It has RS232 and USB device ports. The cables are not included.

Can I use the PX124 for legal-for-trade weighing?

The PX124 is a laboratory analytical balance. For buying or selling by weight in the U.S., choose an NTEP-approved model; call us and we will match one to your use.

What is the difference between the PX124 and the PX124/E?

Both weigh 120 g x 0.1 mg. The PX124 has internal InCal calibration; the PX124/E calibrates with external weights.