M501 USB PDF Single Use Temperature and Humidity Data Logger
Encrypted PDF report at the destination, no software required
The M501 records temperature and humidity for food, pharmaceutical and chemical cargo during storage and transportation. It is designed for one way freight where the device stays with the shipment: your consignee plugs it into any computer and an encrypted PDF report is generated automatically, with no driver, licence or software installation at the receiving site.
Manufactured by HLY Technology with NIST traceable three point calibration and IATA aviation certification, the M501 is used across refrigerated containers, reefer trucks, cold storage warehouses and laboratories.
- Temp range
- -30 to 70°C
- Accuracy
- ±0.5°C
- Capacity
- 14400 readings
- Recording
- Up to 90 days
What the M501 is built to do
Cold chain shipments fail quietly. A reefer unit cycles wrong for six hours somewhere between the port and the distribution centre, nobody notices, and the first sign of trouble is a rejected delivery or a product recall weeks later. The M501 exists to make that invisible failure visible, and to make it provable.
It is a single use logger, meaning it is armed once, travels with the cargo, and produces its report at the end of the journey. There is no configuration software, no pairing, and no return logistics to manage. For one way export freight, that removes the biggest practical objection to temperature monitoring: nobody has to remember to send the device back.
Why single use suits export freight
- No return shipping cost and no risk of the device being lost at the consignee
- Nothing to reconfigure between shipments, so warehouse staff need no training
- Lower unit cost than reusable loggers, which matters at high shipment volume
- The report stays with the consignee as their own record of receipt condition
How the report works
The M501 has a built in USB 2.0 connector under the cap. When it is plugged into a computer, the logger stops recording and writes an encrypted PDF report directly to the device, readable in any PDF viewer. The encryption means the file cannot be edited after generation, which is what makes it usable as evidence in a claim or an audit.
The report contains the full temperature and humidity curve, the configured alarm limits, every alarm event, the mark points made during transit, and the device serial number. Because it is a plain PDF, it can be forwarded, archived or attached to a claim without any special handling.
Where it is used
The M501 is applied throughout warehouse storage and cold chain logistics, including refrigerated containers, refrigerated trucks, cold rooms, conservatory gardens and laboratory environments. It suits food, pharmaceutical and chemical cargo equally, since the measurement range of -30 to 70°C covers frozen, chilled and ambient controlled shipments in a single device.
Four steps from arming to report
One button controls the entire device. No app, no pairing, no configuration screen.
Start the logger
Press the button for 3 seconds until both LEDs light up. The RUN LED then flashes every 5 seconds, confirming the logger is recording.
Attach to the goods
Place the logger with the cargo, inside the pallet, carton or container. The IP67 housing means condensation and washdown are not a concern.
Make a mark
Press the button once at any handover point. The RUN LED lights for 1 second to confirm. Up to 8 marks can be recorded on one journey.
Get the report
Plug the USB into any computer. The logger stops automatically and generates an encrypted PDF report, ready to read or forward.
Stopping manually is also possible when the button off feature is enabled: hold the button for 5 seconds until both LEDs light up, then the RUN LED stays solid to show the logger has been used.
M501 full specifications
Complete measurement, recording and physical specification for the M501 single use temperature and humidity data logger.
Measurement and recording
| Recording options | Single use |
|---|---|
| Temperature range | -30°C to 70°C (-22°F to 158°F) |
| Temperature accuracy | ±0.5°C / ±0.9°F |
| Humidity accuracy | ±3% RH (at 25°C, 20 to 90% RH) |
| Data storage capacity | 14400 readings |
| Recording interval | 10 minutes, customizable |
| Recording cycle | Up to 90 days |
| Alarm mode | High and low limit |
| Alarm type | No alarm, single, accumulated |
| Calibration | Factory 3 point calibration, NIST traceable |
Device and operation
| Start mode | Manual |
|---|---|
| Stop mode | Manual, USB connection or date limit |
| Report | Encrypted PDF report |
| USB connection | USB 2.0 |
| Indicator | LED |
| Battery | 3.0V lithium, CR2450, removable |
| Shelf life | 1 year |
| Protection class | IP67 / NEMA 6 |
| Dimensions | 73 x 30 x 6 mm (L x W x H) |
| Weight | Approx. 13 g |
| Minimum order quantity | 5 pieces |
Recording interval, alarm thresholds and start delay can be preset at the factory to match your shipping profile. Tell us your lane and required limits at the quotation stage.
What sets the M501 apart
Removable CR2450 battery
Our logger uses a large capacity CR2450 cell that can be removed, giving stable performance and a longer service life. Many competing loggers seal in a smaller CR2032 that cannot be taken out.
90 day recording, 14400 points
A 30 minute start delay and a 10 minute logging interval come preset from the factory, filling 14400 memory points across a recording cycle of up to 90 days.
USB plug and play
USB 2.0 connects straight to any computer to produce the PDF report directly. No cable, no cradle, no reader and no software installation at the receiving site.
Automatic report generation
Connect the device to a computer and an encrypted PDF report is created automatically, ready to forward or archive.
Ultra low power design
Minimal current draw is what allows a 90 day recording cycle and a one year shelf life before deployment.
NIST traceable calibration
Three point factory calibration traceable to NIST, so the datasheet accuracy is the accuracy inside the container.
IATA certification
Meets IATA aviation certification standards, so the logger can travel on air freight lanes without extra paperwork.
One button operation
Armed with one press, marked with one press, stopped by USB. No configuration screen and no staff training needed.
IP67 waterproof housing
Sealed to IP67 and NEMA 6, so condensation, ice and washdown in a reefer are not a concern.
Temperature and humidity
Both curves are recorded and both appear in the same PDF report, across 0 to 100% RH.
Compact and light
73 x 30 x 6 mm and around 13 g, so it fits inside a carton or pallet wrap without taking usable space.
Dimensions, parts and LED indication
Everything the operator needs to read the device without opening a manual.
Device overview
- Start, mark and stop button
- Alarm LED indicator
- Running LED indicator
- Waterproof package, IP67 rated
- USB 2.0 port under the cap
- Unique serial number
- Factory default setting label
LED indication
| Start logging | Both LEDs light up for 1 second |
|---|---|
| Logging | Running LED flashes every 5 seconds |
| Mark | Running LED lights up for 1 second |
| Alarm | Alarm LED flashes every 5 seconds |
| Stop logging | Running LED becomes solid |
| USB connecting | Both LEDs flash until the PDF report is generated, then both become solid |
Where the M501 is deployed
The M501 is used for recording temperature and humidity across warehouse management, logistics transportation and cold chain distribution.
Ocean going freighter
Multi week sea legs where a 90 day recording cycle covers port to port with margin for delay.
Refrigerated truck
Road distribution and last mile delivery, including multi drop routes with repeated door openings.
Refrigerated container
Reefer containers on intermodal routes where the cargo changes hands several times before arrival.
Cold storage warehouse
Zone by zone verification in chilled and frozen rooms, and mapping studies during qualification.
Conservatory and greenhouse
Humidity and temperature records for controlled growing environments and plant transport.
Laboratory and reagent storage
Sample transport and reagent shipments where an auditable record of receipt condition is required.
Is the M501 the right model for your lane?
The M501 reports at the destination. If you need to act on an excursion while the cargo is still moving, a real time model is the better fit.
| Specification | M501 | M502-TH | M371 / M381 |
|---|---|---|---|
| Type | Single use | Reusable | Real time, single use |
| Reporting | PDF at destination | PDF at destination | Live to cloud platform |
| Temperature accuracy | ±0.5°C | ±0.3°C | ±0.3°C |
| Display | LED only | LCD screen | LED only |
| Recording cycle | Up to 90 days | 3 to 4.5 months battery | Up to 100 days |
| Alarm notification | In the report | On screen and in report | SMS and email in transit |
| Protection class | IP67 | IP67 | IP65 |
| Best suited to | One way export freight | Closed loop routes | High value lanes |
| Minimum order | 5 pcs | 5 pcs | 5 pcs |
| Product page | You are here | View M502-TH | View M381 4G |
Many shippers run a mixed fleet: real time devices on high value or high risk lanes, and the M501 on everything else. We can quote both in one order.
M501 questions from buyers
Can the M501 be reused on a second shipment?
No. The M501 is a single use logger. Once it has been stopped and the PDF report generated, the unit has completed its cycle and is not intended to be armed again. If you need a device that can be redeployed without reconfiguration, the M502-TH reusable logger is the correct model.
What software is needed to open the report?
None. The M501 writes a standard encrypted PDF file when it is connected to a computer. Any PDF viewer will open it, on Windows, macOS or Linux. There is no driver to install, no licence to buy and no account to create at the receiving site.
How long can the M501 record on one shipment?
Up to 90 days at the default 10 minute logging interval, with a storage capacity of 14400 readings and a 30 minute start delay preset from the factory. Shorter intervals give higher resolution but a shorter total cycle. Tell us your typical transit time and we will confirm the interval that fits.
What battery does the M501 use, and can it be replaced?
The M501 uses a large capacity 3.0V CR2450 lithium coin cell, and the cell is removable. Many competing single use loggers seal in a smaller CR2032 that cannot be taken out. A removable cell simplifies compliance with battery waste rules in the destination market and supports the full 90 day cycle with a one year shelf life before use.
Is the M501 calibrated, and is a certificate available?
Yes. Every unit receives three point factory calibration traceable to NIST before dispatch. If your quality system requires an individual calibration certificate per serial number, raise this at the quotation stage so we can confirm the correct configuration for your order.
Can it be shipped by air?
Yes. The M501 meets IATA aviation certification standards, which is why it is commonly used on air freight lanes for pharmaceutical and perishable cargo. Confirm the specific requirements of your carrier and destination country before booking.
Can alarm limits and logging interval be preset for us?
Yes. Recording interval, high and low alarm thresholds, start delay and alarm type (single or accumulated) can all be configured at the factory before shipping, so the device arrives ready to arm with one button press. This is included with OEM and ODM orders and available on standard orders on request.
Does the M501 record humidity as well as temperature?
Yes. Humidity is recorded alongside temperature with an accuracy of ±3% RH measured at 25°C across the 20 to 90% RH band. Both curves appear in the same PDF report.
What is the minimum order quantity for the M501?
The minimum order quantity is 5 pieces, the same across our whole data logger range. That low threshold is deliberate: it lets you run a real trial on one lane, read the PDF report your own consignee receives, and confirm the device suits your process before committing to volume.
OEM and ODM orders that require custom housing, private label printing or firmware changes carry a higher minimum, since tooling and setup are involved. Contact our sales team with your quantity and destination and we will confirm pricing and lead time for your case.
Other HLY data loggers
M502-TH
USB Reusable Temperature and Humidity Data Logger
LCD display with live readings and alarm status, ±0.3°C accuracy, redeployable on closed loop routes without reconfiguration.
M371
3G Real Time Temperature and Humidity Data Logger
Pull the strip and it starts uploading to the H7 cloud platform, with SMS and email alarms while the cargo is still in transit.
M381
4G Real Time Temperature and Humidity Data Logger
Full band 4G for cross border lanes, with blind area retransmission so no reading is lost in low coverage zones.
Get M501 pricing for your lane
Send us your route, required temperature range, transit duration and monthly volume. We will confirm the recommended logging interval, alarm preset, unit price and lead time. The minimum order is only 5 pieces, so a trial run on a single lane costs very little before you commit to volume.
- Manufacturer
- HLY TECHNOLOGY CO., LIMITED
- Office
- Baoan District, Shenzhen, Guangdong, China
- Phone
- +86 1331 8318 365
- sales@hly-logger.com