HYDROMEA Luma X User manual

a fast, long-range, optical underwater communication system
Manual
Ver 1.4
3/2022

2 LUMA X 3/2022
Contents
1 Introduction ............................................................................................................................ 4
2 Operation ................................................................................................................................ 4
2.1 Initial setup guide ............................................................................................................. 4
2.1.1 Windows 10 setup .................................................................................................... 5
2.1.2 LUMA X setup ............................................................................................................ 6
2.1.3 Setting the IP address ............................................................................................... 7
2.1.4 Setting modems to Active Mode .............................................................................. 8
3 Modem configuration ............................................................................................................. 9
3.1 LUMA X web configuration menu .................................................................................... 9
3.1.1 Main page ............................................................................................................... 10
3.1.2 Parameters page ..................................................................................................... 10
3.1.3 Status page .............................................................................................................. 12
3.1.4 IP address change page........................................................................................... 13
4 Modem configuration and testing using LumaConf ............................................................. 14
4.1 LumaConf parameters .................................................................................................... 17
4.2 Firmware upgrade and factory reset ............................................................................. 18
4.3 Communication test ....................................................................................................... 19
4.4 Recording a log file ......................................................................................................... 21
4.5 Visualizing a log file ........................................................................................................ 21
5 Maintenance ......................................................................................................................... 21
6 API ......................................................................................................................................... 22
6.1 API parameters ............................................................................................................... 22
6.2 Usage examples .............................................................................................................. 24
7 Electrical and software Characteristics ................................................................................. 25
8 Mechanical Characteristics ................................................................................................... 26
9 Errata ..................................................................................................................................... 28

3 LUMA X 3/2022
WARNING:
 bright LED light source, do not look directly at emitter
 a few people may experience epileptic seizures when
viewing flashing lights

4 LUMA X 3/2022
1 Introduction
The LUMA X is an optical modem for fast, reliable wireless underwater communication. Each
LUMA X is a full transceiver and thus capable of half-duplex communication (transmission and
reception).
2 Operation
Note: while submerging the LUMA X, a small number of bubbles may come out of the
pressure compensation vent at the connector end of the modem. When LUMA X is back on
the surface a small amount of water may come out of the vent.
2.1 Initial setup guide
Note: before first operation, the LUMA X needs to be configured.
The following sections describe the initial network setup and LUMA configuration.
On factory default, LUMA X has the default IP address 192.168.102.101, and will send telemetry
to a host computer that has the IP address 192.168.102.100. The first step is thus to set the
host computer to this address for the initial configuration.
For the purpose of initial setup and testing, the default network configuration and IP addresses
are used, as shown in Figure 1. For operational use, the IP addresses of the LUMA X modem and
the computers connected to them can be configured differently to suit individual network
requirements.
Note: As the LUMA modems form a bridge, they should not be connected to the same cabled
network (i.e. do not plug both modems into the same switch). Doing so may lead to a loop in
the network, where one LUMA picks up traffic from the other LUMA and feeds it back to the
switch, flooding the network with packets. The modems should be connected to two separate
cabled networks as shown below.
Figure 1: Typical initial test setup

5 LUMA X 3/2022
2.1.1 Windows 10 setup
On Windows 10 this is set up as follows:
 go to → Settings → Network & Internet → Ethernet (in left column) → Network and
Sharing Center (in right column) → Change adapter settings (in left column) → right click
on Ethernet adapter → Properties → select Internet Protocol Version 4 (TCP/IPv4) →
Properties
 set the address as shown in Figure 2
Verifying the IP address setting:
 Open a command line: → Windows PowerShell
 Type: ipconfig /all
Figure 2: Windows 10 network settings

6 LUMA X 3/2022
 You should see the IPv4 address setting shown in Figure 3
Figure 3: IPv4 address settings for LumaConf
On the remote PC, repeat the procedure, but set the IP address to 192.168.102.103.
2.1.2 LUMA X setup
Once the host computer’s IP address is set correctly the connection to the LUMA X can be
tested.
 Connect only one LUMA X to a computer via an Ethernet connection using Hydromea’s
power/data cable.
 Connect the LUMA X to a suitable supply voltage (12 V – 36 V) using Hydromea’s
power/data cable.
 (Optional step) To test that the IP address has been set correctly, the computer should
now be able to ping the LUMA X on its default IP address 192.168.102.101 and the
modem should respond to it.
o Windows 10: Open a command line: → Windows PowerShell
o enter ping 192.168.102.101

7 LUMA X 3/2022
 Open a browser, and enter 192.168.102.101 into the address field. The LUMA X web
interface main page should appear (see Figure 4)
All LUMA X are factory-set to boot-up into config mode and their factory-set IP address is
192.168.102.101.
In order to use several LUMA X within the same network for configuration and testing, they
need to be set to differing IP addresses. Please follow the steps in the following section to
change the IP address of the second modem.
2.1.3 Setting the IP address
For the initial test, modem (1) can remain at the default IP address. The other modem (2) has to
be set to a new IP address that is unique within the subnet. For the initial example, we use
192.168.102.102.
 Plug in only modem number (2) and navigate your browser to 192.168.102.101
 Click on the menu item “IP change”
 Enter the new IP address 192.168.102.102 (for the second modem)

8 LUMA X 3/2022
 Click “Set”. The new IP address is now temporarily applied, and the page will reload
showing the new IP address:
 To store the new setting to flash memory, click “Save”. The modem is now set to the
new IP address.
2.1.4 Setting modems to Active Mode
The LUMA X has two modes of operation: config and active.
The config mode is the inactive mode and the modem will not forward data between the
ethernet cable and the optical interface.
After setting the configuration, LUMA X can be switched to active mode. It will now behave as a
bridge device, forwarding any traffic from the cable side via the optical link. This effectively
connects the networks on both sides, comparable to a cabled connection between two
switches or end devices.
For purposes of the initial test, we will leave all parameters on default values, and switch the
two modems to “active” to establish a link.
 Plug in the first modem and power it up, load the web interface (as previously)
 Click on the menu item “Parameters”
 Change “Default start state” to “Active”
 Click “Set”
 Click “Save”
 Unplug the modem, repeat all steps with the second modem.
 At the next power-up, the modems will operate in “active” mode.
The modems are now ready. Connect the first modem to the Operator PC, and connect the
second modem to a remote PC (e.g. a second laptop, or an ethernet-capable remote device).
The operator PC should be set to IP address 192.168.102.100. The remote PC should be set to
IP address 192.168.102.103 (this IP address is given as an example for the initial setup – it can
be chosen freely within the same subnet).

9 LUMA X 3/2022
Power up the modems on both sides. The boot-up takes up to 10 seconds.
On the operator PC, open a Shell, and type:
ping 192.168.102.103
If everything is configured correctly, the modems will visibly flash with blue light, and the ping
will show the response from the remote PC.
The optical link is now ready and will forward any ethernet traffic from one side to the other
side.
Note that ambient light, artificial light sources (fluorescent office lighting, LED lamps, screens,
sunlight) may interfere with the optical channel and disrupt communication. If a link cannot be
established, try to turn of lights, or cover the modems with an opaque sheet of cardboard or
cloth while ensuring line of sight between the modems. Ideally the modems should be
separated by at least 1 meter, as the receiver may saturate at very close range.
3 Modem configuration
This chapter will describe the modem configuration in detail.
There are two ways to configure LUMA X, the built-in web interface as well as LumaConf, an
external program. The web interface is the preferred way to configure LUMA X. LumaConf
offers some additional test features that provide several performance metrics for a two-modem
connection.
This chapter details the configuration of LUMA X using the web interface and chapter 4 explains
the configuration via LumaConf.
3.1 LUMA X web configuration menu

10 LUMA X 3/2022
3.1.1 Main page
Figure 4: main page of the web-based configuration-UI
This page provides information about the current revision of the hardware, firmware and API. It
also provides the firmware’s SHA and the unique processor ID.
3.1.2 Parameters page
Figure 5: parameter page of the web-based configuration-UI
This is the main configuration page for the LUMA X. Hovering over the “?” next to each
parameter provides a short description.

11 LUMA X 3/2022
Note: No change will become effective until the Set button has been pressed. After power-
cycling the modem the parameters will revert to the previous setting. Pressing the Save
button will store the new set of parameters into the LUMA X flash memory and make it the
new permanent set of parameters.
Default Start
State
Config
Active
The state which the LUMA X will boot into. This is factory-set
to config, but for normal operation this should be set to
active. The mode will be applied at the next power-up.
Optical speed 1 MHz
2 MHz
4 MHz
6 MHz
8 MHz
10 MHz
Speed of the optical link. Note that higher transmit speeds
mean less range. Both sides have to be set to the same
speed.
Number of
active LED
banks
1
2
3
4
5
Number of LED banks used for transmission. Increasing the
number of banks increases the transmission range and power
consumption.
Encoding On
Off
Enabling Encoding, improves the link quality at the cost of
throughput
LED transmit
power normal
1% - 100% Power level of LEDs during normal operation. Note: if 2 LUMA
X are very close to each other (less than 50 cm), packet loss
can be reduced by reducing LED power.
LED transmit
power
cooldown
1% - 100% Power level of LEDs during cooldown operation, when the
modem cools down from 55°C to 50°C.
Auto gain
control
On
Off
The LUMA X will adapt to the ambient light level by changing
the receiver gain. Note: this should be enabled in an
environment which experiences ambient light changes.
Gain value 0-4000 Receiver gain
If Auto gain control is on, the current gain value is displayed,
but cannot be changed.
If Auto gain control is off, it is a mutable parameter.
Number of
active receivers
1
2
3
4
The LUMA X modem has 4 receivers and any number of them
can be active.
If Auto gain control is on, this will be selected automatically
by the LUMA X during active operation, otherwise it is a
settable parameter.
If Auto gain control is off, it is a mutable parameter.
Autogain
control
0-4000 This is the target value for the auto-gain algorithm. The
factory default value is normally the best choice. In some
situations, this parameter can be adjusted based on a gain

12 LUMA X 3/2022
amplitude
adjust
tuning procedure (contact Hydromea for assistance if
required).
Keep-alive
packets
On
Off
When on, the modem will send short packets every 1-2
seconds, which helps to maintain optimal gain settings. When
off, the modem will not emit any light unless there is data
traffic, but there may be packet loss immediately after longer
pauses in data flow until the gain control can adjust.
Table 1: parameters within the web-based configuration UI
3.1.3 Status page
Figure 6: status page of the web-based configuration-UI
This page provides information about the current status of the LUMA modem and is updated
once every second. All information provided refers to the last one-second-window.
Temperature LUMA Temperature (in degree Celsius) of the optical transceiver. When it
reaches 55°C the modem will automatically reduce the power to the
transmitter LEDs until the temperature has dropped to 50°C
Throughput received
(kbps)
Average data rate for data received
Packets CRC errors Number of packets discarded in last second due to CRC error
(indicator for the stability of the link)
Packets received Number of error-free packets received within the last second
Packets lost Number of packets lost within last second between successfully
received packets.
Note: if no packet is successfully received, lost packets cannot be
tracked.
Table 2: modem and link information provided by the web-based configuration UI

13 LUMA X 3/2022
3.1.4 IP address change page
Figure 7: IP-setting page of the based configuration-UI
This page lets you modify the IP address of the web-based configuration interface (which you
are using right now). The current IP address of the of the web-based configuration interface is
displayed and can be changed. Changing the IP address and pressing Set button will
immediately change the IP address, however this change is not permanent and the change
would be reverted during a power-cycling. After pressing Set button, the webpage will try to
reconnect to the web-based configuration interface using the new IP address. After reloading
the page, the new IP address will be shown and a Save button is available. Pressing the Save will
store the new IP address in the modem’s flash memory, thus making the change permanent.

14 LUMA X 3/2022
Figure 8: saving the IP address to flash in the web-based configuration-UI
4 Modem configuration and testing using LumaConf
In addition to the web-based user interface, the LumaConf software offers some additional
features. It is available here:
https://files.hydromea.com/luma/LumaConf_lumaX.zip
Note: when starting LumaConf you will get a “Windows protected your PC”-notification, as
LumaConf is currently not yet signed. Please click on “more info” and then on “Run anyway”.
To configure LUMA X we recommend using the web-based interface (see chapter 3.1).
LumaConf offers a built-in test tool to assess the quality of a link between two modems.
LumaConf also provides an option to upgrade or reflash the modem’s firmware. These two
capabilities are only available in LumaConf.
The LUMA X has two modes of operation: config and active.
The config mode is the inactive mode and the modem will not forward data which it receives
optically onto the Ethernet cable. When using LumaConf to change LUMA X’s configuration the
modem needs to be in config mode.
To use LumaConf, ensure that the LUMA X is connected to a computer via Ethernet and that it is
powered up. After the start of LumaConf you will see the console shown in Figure 10.
The upper half of the LumaConf console provides the control elements outlined in Table 3.

15 LUMA X 3/2022
Note: If LumaConf cannot connect to the LUMA X, it will display “No LUMA connected”. Verify
that your host PC is set to the IP address 192.168.102.100 (or respectively, the address
specified as the “Host IP address” in the LUMA X parameters).
You may also need to disable the firewall for LumaConf.
In Windows 10:
 → Settings → Network & Internet → Windows Firewall (in center column) → Allow an
app through the firewall
 Check LumaConf as shown in Figure 9
 The LUMA X should immediately appear on the LumaConf user interface.
Figure 9: Windows 10 firewall exception settings for LumaConf

16 LUMA X 3/2022
Figure 10: LumaConf main console
1 Selector for the interface to communicate with LUMA X (Ethernet, serial/USB). The
serial interface can only be used to change the LUMA X’s IP address, update its
firmware and to reset it to factory settings.
2 Selector for the baud rate of the serial interface (only selectable when a serial
interface is selected in 1)
3
Selector for LUMA X. If multiple LUMA X are detected, their last IP address byte will be
displayed in this drop-down list. The LUMA X which is to be configured can then be
selected from this list.

17 LUMA X 3/2022
4 Button to refresh the list of parameters in the bottom section of LumaConf for the
LUMA X selected in 3.
5 Button that puts the LUMA X specified in 3 into config mode. This will change the
lower half of the LumaConf console so that the modem parameters can now be
changed.
Note: this will only be required if the attached modem is currently in active state and
will thus not be automatically visible in LumaConf. Clicking on Config mode will bring
up a box requiring you to enter the Configuration IP address of the attached LUMA X.
If the configuration IP address is unknown, you can factory reset the LUMA X (see
section 4.2 which will reset the Configuration IP address to 192.168.102.101 and set
the default state to config and thereby ensures that the LUMA X will show up in
LumaConf after a reboot.
6 Button that saves the parameters shown in the lower half of LumaConf into the LUMA
X’s flash memory.
7 Button that loads the parameters from the LUMA X’s flash memory, thus canceling
any unsaved changes.
8 Button that starts a communication test between two LUMA X. See section 4.3 for
details.
9 Button that will open a dialog to run a defined communication test between two
connected LUMA X. This will output a logfile for troubleshooting. For more details see
section 4.4
10 Button that starts the firmware bootloader dialog for IP address change, firmware
update or factory reset. See section 4.2 for details.
11 Button to convert a previously generated log file into a graph. For more details see
section 4.5
12
Hardware version of the LUMA X
13
Software version of the LUMA X
14
Firmware version of the LUMA X
Table 3: control section of LumaConf
Note: For normal operation, the user should set the parameter Default state to active in
LumaConf and Save, allowing the LUMA X to start into active mode at the next power-up.
Both LUMA X of a communication link need to be in active mode for normal operation.
4.1 LumaConf parameters
Successfully setting a LUMA X into config mode makes the parameters in the lower half of the
LumaConf main console changeable. Table 1 in chapter 3.1.2 provides an explanation of the
parameters.
The only additional parameter not present in the web interface is the “Host IP address”. This is
the target address where LUMA sends the telemetry to, and has to match the IP address of the
PC where LumaConf is running.

18 LUMA X 3/2022
4.2 Firmware upgrade and factory reset
In order to upgrade the firmware of LUMA X or carry out a factory-reset, LUMA X must be put
into Bootloader mode. The following steps will upgrade LUMA X firmware and/or carry out a
factory reset:
 Start LumaConf
 Ensure that the LUMA X is connected to a computer through the serial connection. This
is most easily achieved by using Hydromea’s power/data cable-box which provides a
serial connection through a USB-to-serial conversion within the power/data cable and
can be accessed via a micro-USB port.
 Ensure that the LUMA X is connected to a power supply
 In LumaConf set Interface to the correct serial port
 Click on Firmware update within LumaConf. This will open the Bootloader dialog box
(see Figure 11).
 Cycle the power for LUMA X
 The user now has a few seconds after start-up to discover the LUMA X by clicking the
Discover button. Once it appears in the Devices window, the LUMA X will stay in
bootloader mode and more options will be available to the user.
o Firmware update+factory reset: select the proper firmware file by clicking on
Select … and then start the update by clicking on Write Flash. Wait for the
progress bar to reach 100%. After a firmware update a factory reset will also be
carried out automatically.
Note: please make sure that you select the proper firmware image, the last
digits of the filename LX########## need to match the serial number
engraved on the modem.
o Factory reset only: clicking on Clear Settings will factory reset all LUMA X
settings.
 Clicking on start Application will cause the attached LUMA X to exit the bootloader and
restart. The LUMA X will restart in config mode as a firmware update will also cause a
factory reset which sets the Default state after reboot to config.
 Closing the bootloader window and selecting Ethernet in Interface will then lead to the
LUMA X showing up in LumaConf.
Note: a limited set of options is available in the Bootloader menu when one or multiple
LUMA X is/are connected via Ethernet and in config mode. In this case the Bootloader
window will list all LUMA X connected to the network with their last IP byte as an index.
The only available actions in this mode are reading the unique serial number of a LUMA X
by clicking on Get Info which then shows the serial number in Processor ID or to soft reset
the attached modem(s) by clicking on Reset.

19 LUMA X 3/2022
Figure 11: Bootloader section of LumaConf for upgrading the firmware or factory reset of LUMA X
Discover Query and display all connected LUMA X.
Reset all Reset all connected LUMA X
Get info Retrieve the processor ID of the selected LUMA X
Firmware (only in serial) selects the firmware cfi file for upgrade
Write
Flash
(only in serial): Programs the firmware to the LUMA X. It is completed once the
transfer progress bar reaches 100%. In case of transfer error, the bar will regress
to 0%
Clear
settings
(only in serial): Will factory-reset the parameters on the LUMA X, such as its IP
address and the config/active mode into config.
Start
application
(only in serial): Will start the LUMA X. Note: power cycling the LUMA X and
closing the Firmware upgrade window will not put LUMA X into bootloader
mode and it will start normally as well.
4.3 Communication test
When two LUMA X are connected via Ethernet and are in config mode, a communication test
can be carried out using a simple communication test tool built into LumaConf.

20 LUMA X 3/2022
Clicking on Comm. test with 2 LUMA X connected opens a window shown in Figure 12. Checking
one of the Send random data options (low or high throughput) will make the corresponding
modem send random data. The rate at which the data is received by the other modem will then
be displayed on the opposite side. For example, Figure 12 shows a LUMA X with the last byte of
its Configuration IP address being 102 sending random data with high throughput which is
received by LUMA X with the last byte of its Configuration IP address being 101 at 10 Mbps.
Both modems can send random data at the same time which allows you to test the half-duplex
channel between both modems. Please note that operating the modem at a high-power level
and a high data rate while not submerged in water will quickly increase the modem
temperature which is also displayed in the communication test utility.
Figure 12 LumaConf's communication test utility with two modems connected and modem 102 transmitting random data at 10
Mbps, received by modem 101