Brother DS-940DW portable duplex document scanner

Brother DS-940DW
100% human

The Brother DS-940DW is a portable, single-pass, duplex scanner – something very few $299 products do, let alone portable ones with Wi-Fi, USB 3.0 and a battery.

The Brother DS-940DW is almost unique (and its nearest competitor is the Epson ES-60W, and I have used it too) but before you rush out and buy, we want to issue some caveats that apply equally to both.

  • Meant for casual/mobile users – a few sheets at a time
  • The design – small feed and receive rollers – means documents can skew
  • It is a sheet feed – not a hand scanner
  • It works best with 60-80gsm bond paper.
  • Take care with light stock (use a carrier sheet)
  • If heavier stock does not feed don’t force it
  • It does not have user-replaceable rollers, or parts – when it stops feeding or charging that is it

In other words, don’t use the Brother DS-940DW – a 4-cylinder to tow a caravan. In all other respects, it is a great little scanner that adds flexibility to a mobile warrior’s arsenal.

If you need more, then look at a multi-function printer or our favourite desktop scanner – the $499 ADS-1700W duplex scanner.

Brother DS-940DW portable duplex document scanner

  • Australian Website here
  • Manual here (pdf check downloads)
  • Price: $299 but you may find this online for about 10% less
  • Warranty: 1-year

It is part of the DS-640 and 740D family that may suit your needs at a lower price point.

In the box

  • Scanner (512MB)
  • USB-A 3.0 to micro-B cable 1.2m
  • Calibration sheet (use occasionally to reset the scan area)

As it charges via USB micro B there is no plug pack – see battery later

Portable – EXCEED

Yes, it is at 319 x 63.1 x 45.4mm x 699g. In comparison, a sheet of A4 paper is 210mm wide. It is durable in so far as we don’t recommend dropping it, but it will withstand the rigours of a briefcase.

Technology – EXCEED

The key to this scanner’s portability is the use of dual CIS (Contact Imaging Sensors) that eliminate the need for bulky optic lenses, mirrors, RGB filters, separate light sources and CCD (Charged Coupled Device) or CMOS.

To put this in perspective, the paper needs to be pulled by the front roller over the sensors at a consistent rate before being pulled by a rear roller and exiting the rear slot or the U-shaped paper receiver. In other words, it has no flatbed or hand scanner capability.

Brother DS-940DW
Note the small diameter front and rear friction rollers

Paper stock – PASS but take care

We mentioned the best is straight bond paper, but specifications are for up to 270gsm which covers photos and 1mm thick ID cards.

It fed flawlessly with bond but was really pushing to feed glossy ID cards and heavier photos. It did not feed glossy stock.

And this is where the caveat comes in. A single, small feed roller has limitations you need to be aware of. It is also important not to feed paper that might damage or soil the roller. For example, a crayon drawing or OHP transparency is out. No staples, perforations, punched holes etc. Be kind to the roller, and it will be kind to you.

Setup – EXCEED

It works with Windows, macOS, Android, iOS and Linux using standard OS drivers. There is Brother iPrint and Scan app for all OS as well as an embedded web server page to change settings.

But it offers four modes

  • Wi-Fi N 2.4Ghz via a home network router – WPS setup
  • Wi-Fi Direct to your computing device – connect to its SSID
  • USB cable to a PC or Mac
  • Standalone via a microSD card to 32GB

Test – PASS

We tested over Wi-Fi on Windows 10 machine and had a few issues. First is has a relatively small 512MB of memory.

To see if it could achieve 15 pages-per-minute scans, we set the resolution to 600DPI and used a mix of double-sized images and text. It quickly filled the onboard memory buffer and slowed scanning effectively, locking the Windows app until the buffer was clear.

And here is where the caveat appears again – if you need to do 15ppm then get a scanner with a few GB of memory.

The issue was not so evident when using the USB-C cable or microSD card as waiting on buffer clear is less of a problem.

Standalone mode to microSD tends to explain all. You see there is no app controlling it in this mode, so you need to set (using buttons) Colour/mono, PDF/JPEG and 1 or 2 sided.

Bundled apps – EXCEED

Brother has bunded industry-leading document management software, Kofax Power PDF and Nuance PaperPort SE 14. Users have document editing and management capabilities straight out of the box, and at no added cost.

Speed versus resolution – PASS

Regrettably, we did not have a 1.8m long page to test speeds. So, while it may theoretically achieve 15ppm – try manually feeding 15 pages in a minute into a slot – it is not going to happen.

And resolution plays a part too. For text (even colour) 100DPI is fine. For photos 300DPI is fine. You can scan natively at 600DPI and also push it to 1200DPI if you want to reduce speeds to around one page a minute.

Output – EXCEED

Depending on your app, you can select TIFF (BW only), JPEG (Greyscale/Colour), PDF, Secured PDF, Signed PDF, PDF/A-1b, or Searchable PDF. Then you can select scan direct to Dropbox, Google Drive, iCloud, OneDrive (desktop iPS only). The iOS version does not support workflows.

Battery – EXCEED

It has a 3.8V, 1200mA, 4.56W rechargeable battery. In theory, that means it needs a 5V/1A (5W) charger at a minimum as it consumes 4.4W on Wi-Fi and 3.6W on USB 3.0.

The typical laptop port is either 5V/.5A (2.5W) or 5V/1A (5W) so be a little careful. While it works on modern USB 3.0 ports (Blue insert) older USB 2.0 ports don’t have the wattage.

Brother recommends that the battery be charged ‘sufficiently’ before running off USB-A

We tested with a 5V/2A USB-A, 5V/3A USB-C PD charger and a Lenovo Yoga 930 2019 laptop, and it was great. That means it works off USB-C and Thunderbolt 3 desktop docks and dongles as well.

We were unable to test the claim of 200 sheets (Wi-Fi) or 320 sheets (microSD), but it seems reasonable in theory. In practice, I suspect its about 33% of that.

Sound – PASS

It is silent in idle and up to 53dB during scanning.

GadgetGuy Take – Brother DS-940DW portable duplex document scanner is perfect if your needs match it

Use it in the car, office, client, café, boat, plane … but don’t try to use it for more than it is practically cable of.

Duplex convenience and different file outputs/destinations are great. The standalone microSD may lose an apps sophistication, but a scanner is to make a copy and I suspect that is how most mobile warriors will use it.

We will rate it as a portable scanner with commensurate duty cycle – a few pages when you need it – not the theoretical 2,000 pages per month.

If it does not meet your need for speed, then the Brother ADS-1700W duplex portable scanners will.

Value for money
Ease of Use
Reader Rating0 Votes
Small, well designed and built
Duplex scanning can be so handy
Don't expect more than it can practically deliver
Three comms methods and different options for each
Easy to overflow the buffer on Wi-Fi