SeaLogHeinrichs Weikamp
How to import dives from a Heinrichs Weikamp OSTC 2
The Heinrichs Weikamp OSTC 2 exists in both a wired and a Bluetooth LE generation. Try the wireless download first, and if your unit never appears, the cable route further down brings the same dives across.
Download dives from the Heinrichs Weikamp OSTC 2
- Wake the computer and put it in transfer mode
Charge or wake the Heinrichs Weikamp OSTC 2 and open its Bluetooth or PC/upload mode. Most models only advertise for a minute or two, so do this last, right before you pair.
Most units only hold this mode for a minute or two, so do it last, right before you connect. - Open the import hub in SeaLog
In SeaLog, tap the plus button, then Import dives, then Dive computer. Allow Bluetooth when iOS asks. SeaLog never asks for a manufacturer account.
- Pick your model and pair
Choose Heinrichs Weikamp OSTC 2 from the list. If iOS shows a pairing prompt, accept it. Keep the computer in transfer mode until the download finishes.
The unit only advertises for a short window. If it never appears, put it back into transfer mode and try again straight away. - Download the dives
SeaLog pulls every dive still in the computer's memory, with depth profile, water temperature, gas and surface interval, and skips the ones you already have.
- Check and keep
New dives land in your logbook ready to name, place on a site and tag with the species you saw. Nothing was retyped.
If it never shows up: the cable route
The wired generation of the OSTC 2 has no radio at all, so there is nothing to pair with. It goes through a computer once, and after that you can log straight into SeaLog on the boat.
- Install the driver for the cable
The serial cable is a USB-to-serial adapter, and its chipset needs a driver before any software can see the Heinrichs Weikamp OSTC 2. Install the FTDI (legacy USB generation: OSTC 1, OSTC Mk.2, OSTC 2N, OSTC 2C). The Bluetooth generation needs no driver at all: pairing creates a virtual COM / SPP serial port that software talks to directly. driver, then reboot. Skip this and the desktop app will report no device on a cable that is working perfectly.
These cables are USB-to-serial. Without the FTDI driver the port never appears, and the software reports no device. - Connect the Heinrichs Weikamp OSTC 2 to a Mac or PC
Use the serial cable made for the Heinrichs Weikamp OSTC 2, not a generic charging cable: the data pins differ. Check the o-ring is seated, line the connector up with the notch on the case, and turn it to lock. An iPhone or iPad cannot open this kind of connection at all, so this step has to happen on a computer.
The o-ring must be in place, the nub lines up with the notch, then the head turns a quarter turn to lock. This cable is FTDI (legacy USB generation: OSTC 1, OSTC Mk.2, OSTC 2N, OSTC 2C). The Bluetooth generation needs no driver at all: pairing creates a virtual COM / SPP serial port that software talks to directly.. - Put the computer into PC mode
Switch the Heinrichs Weikamp OSTC 2 into its PC or upload mode before you launch the software, not after. Most desktop apps only look for the unit at startup, so a computer that wakes up late is a computer the software never finds.
Most units only hold this mode for a minute or two, so do it last, right before you connect. - Download the dives with desktop software
Read the computer with OSTC Companion and Subsurface or Subsurface. Subsurface is free, open source, runs on macOS, Windows and Linux, and supports this model.
- Export the dives as UDDF
Export the whole logbook to a UDDF file. UDDF is the open dive-log exchange format and keeps the full depth profile, not just the summary numbers.
Export the whole logbook, not the visible page. UDDF keeps the sample-by-sample depth profile, which a summary CSV does not. - Import the file into SeaLog
Get the file to your phone. AirDrop, iCloud Drive or email all work, anything that lands it in the iOS Files app. Then in SeaLog tap the plus button, Import dives, UDDF file, and pick it. Every dive arrives with its profile, and duplicates are skipped.
A dive log app for the OSTC 2
Once the dives are in, SeaLog treats them like its own: a scrubbable depth profile, the site pinned on a map, water temperature, gas and tank, buddies, and the photos from your camera roll matched to the minutes you were underwater. Tag the animals you saw and they go into your species life list. It works offline on the boat and syncs when you are back, and your whole logbook exports to UDDF, CSV or PDF whenever you ask, so nothing is locked in here either.
Heinrichs Weikamp’s own software and drivers
Alive and actively maintained (the company rebranded to "hw diving", heinrichsweikamp.com now redirects to hwdiving.com, and the OSTC Companion installers were rebuilt in October 2025), but it has never shipped a logbook program of its own, so the actual dive-to-file step always happens in third-party software, above all Subsurface, which the OSTC manuals name explicitly.
- Desktop softwareOSTC Companion 3.2.1 (Windows) and 3.0.8 (macOS)One 48 MB archive holding both Windows .exe installers and the macOS .pkg; handles firmware, clock and custom text, but does not read the dive log.Win + Mac
- Desktop softwareSubsurface (the logbook Heinrichs Weikamp's own manuals point you to)Third-party and free, but the OSTC manuals name it as the way to read out dives and even push firmware; it is also the practical route to a UDDF or CSV export file.Win + Mac
- Official guideOSTConf project pageDeveloper's own page describing which OSTC models the iOS app supports and what it can read or change over Bluetooth LE.iOS
- Mobile appHWOS Config for AndroidCommunity app recommended in the official manuals for phone-side firmware updates and custom text; it configures the computer rather than importing dives.Android
- Mobile appOSTConf for iPhone and iPadThe iOS counterpart named in the manuals; talks to the Bluetooth LE models for settings, gases and firmware, with iCloud backup of the configuration.iOS
- FirmwarehwOS Sport firmware v10.98Recreational branch of hwOS; worth applying before troubleshooting Bluetooth download problems.
- FirmwarehwOS Tech firmware v3.37Technical branch of hwOS, covering trimix and rebreather use on the same hardware.
- FirmwareFirmware v3.16 for the legacy USB modelsFinal firmware line for the cable generation, separate from hwOS entirely.
Every link goes to Heinrichs Weikamp’s own site and was checked before publishing. If one has rotted since, tell us and we will fix it.
Heinrichs Weikamp OSTC 2: common questions
Does the Heinrichs Weikamp OSTC 2 have Bluetooth?
It depends on the generation. This model line was sold in both a wired version and a later Bluetooth LE version, and they look almost identical. The quickest way to find out which one is on your wrist is to try the Bluetooth download first: if the computer never shows up while it is in transfer mode with a fresh battery, yours is the wired one and the cable route below is the way in.
Why will my Heinrichs Weikamp OSTC 2 not connect over Bluetooth?
Nine times out of ten the computer has dropped out of transfer mode: it only advertises for a short window, so put it back into Bluetooth or upload mode and try again immediately. After that, check that the battery is not low, that no other app or desktop is already holding the connection, and that Bluetooth permission is granted to SeaLog in iOS Settings. Toggling iOS Bluetooth off and on clears a stale pairing more often than it should.
Which cable and drivers do I need on a Mac?
Use the Heinrichs Weikamp interface cable made for this model, not a generic charging cable: the data pins differ. Most of these cables are USB-to-serial and need the driver for their chipset on macOS, usually Silicon Labs CP210x or FTDI. Install the driver, reboot, and the port appears to the desktop software.
Does the depth profile come across, or just the numbers?
The full profile. SeaLog stores the sample-by-sample depth, temperature and ascent data, draws it as a graph you can scrub, and can export the whole thing back out to UDDF at any time.