Connecting devices using a Serial-To-Ethernet converter

This tutorial shows how to connect NMEA0183 compatible devices (GNSS receiver or echo sounders) using a Serial-To-Ethernet converter. In this example we will show how to setup a Moxa N-Port series, your network adapter and Hydromagic in order to receive data from a GNSS receiver or echo sounder. We used the Moxa N-Port 5110 Serial Device Server, but it should apply to other models, including multi-port converters.

A Moxa N-Port 5110 Serial Device Server

Connecting the Moxa N-Port to your PC

First connect your Moxa N-Port device to your PC in order to configure it. Please note that you can not connect it directly to your PC with a standard Ethernet cable. You need to use a cross cable, or connect the device to your computer via an Ethernet hub, router or switch. After connecting the device to your computer, the "Link" LED on the device should be green. If it is off, there is a problem with the connection.

When it is connected, make sure that the Ethernet adapter is properly configured to make a connection with the Moxa. Go to your Windows Start menu, and type "Ethernet Settings", and launch the "Ethernet Settings" tool. Locate the network adapter that is going to be used, click it and click the "Edit" button under the "IP settings" section.

If the Ethernet adapter is currently configured with other settings, save them in case you need them later. Please see the screenshot below for the settings needed to communicate with the Moxa device.

Configuration of your network adapter

Resetting the Moxa N-Port device to factory defaults

In case you want to setup the Moxa and your network from scratch, please reset the device to it's factory defaults. To do so, locate the micro switch next to the Ethernet connector. Press and hold this micro switch for about 5-10 seconds until the "Ready" LED starts blinking. when done, you should be able to connect the device's internal web configuration at http://192.168.127.254 which can opened using your web browser.

The default user name (not applicable for all models) is "admin", while the default password is "moxa". After entering the credentials, you should reach the main page of the Moxa's internal web server, which should look similar to the image below:

Home page of the Moxa's internal webserver

Configuring the Serial Port(s)

The next step is to configure the serial port your device is connected to. Some converters have more then one serial port. In this case, select the correct settings for each port you will connect a NMEA0183 device to. By default most NMEA0183 devices operate at 4800bps, but especially for GNSS receivers, higher speeds are more common.

To access the serial port settings, expand the "Serial Settings" item in the folder tree at the left of the screen. For each device you will be using, set the correct serial speed and flow control. When unsure how to set the flow control setting, just disable it. After modifying a setting, always click the "Submit" button to apply changes.

Select the correct speed and flow control settings

Configuring Operation Mode

The operation mode defines how the incoming serial data is forwarded over the Ethernet port. The easiest method to broadcast the NMEA0183 data over your network is by using the UDP. Other available modes include "TCP Server" and "TCP Client". First, select the "UDP Mode" setting from the "Operation mode" drop down box.

In order to send one UDP data packet per incoming NMEA0183 sentence, we have to tell the device how it can detect that a NMEA0183 sentence ends. To do so, enter "0D" or "D" as Delimiter 1 and enable detecting of this character (0x0D is the hexadecimal representation for a newline).

You can enter up to four IP addresses where the data is sent to. Make sure it includes the IP address of your own PC, which should be in the same IP address range as the Moxa device (192.168.127.1 - 192.168.127.253 in this example). When connecting the Moxa via a WiFi access point, make sure it is in the same range as well, and UDP or UDP port number 4001 isn't blocked by an internal firewall. When the operation mode has been configured, click "Submit" to apply the settings.

Set the operation mode to UDP to broadcast data

Storing Configuration

After modifying one ore more settings, the Moxa device will ask you whether to save the settings and restart the device. Since it only takes a couple of seconds to restart, we recommend you to do this each time you want to experiment with a modified setting. Just click the "Save/Restart" button when shown in the web-interface.

It is recommended to click the "Save/Restart" button after modifying one or more settings

Loading the NMEA0183 plugin

To add a NMEA0183 compatible device to the configuration, select "Preferences..." from the "Options" menu (or click the "Options" button in the toolbar) and select the "Devices" tab:

Select the "Devices" tab from the "Preferences" window.

In the devices tab, click the "Add..." button to load a NMEA0183 plugin. You can load a maximum of four (4) NMEA0183 plugins simultaneously. Next, select the first available "NMEA0183 plugin" in the "Select Device" dialog which appears after clicking the "Add..." button and click "OK" to show the plugin's configuration options.

Select one of the "Hydromagic NMEA0183" plugins from the list and click "OK".

Communication Settings

After the plugin has been loaded, a configuration dialog is displayed where you can pass the required information to the plugin. First of all, change the "Connection Type" setting from "Serial" to "TCP/IP" as we are using Ethernet or WiFi to connect. Depending on the operation mode chosen in the Moxa web interface, select either "TCP" or "UDP". In this tutorial we used UDP, so if you are strictly following this tutorial, set the "Socket Type" setting to "UDP".

The "Host IP" and "Host IP Port" settings should be visible. Depending on how we configured the Moxa, we enter the IP address of the Moxa as well as the TCP/IP port configured in the operation mode settings. In this example this is respectively "192.168.127.254" and "4001". After configuring the plugin, just click "OK" to save the settings and start listening.

Configure network settings (UDP)

Troubleshooting

When no data is coming in, or you do not know what transducer names are used by your device, you can use the 'Communications Monitor' on this plugin to check the incoming data. In cases where there is no data coming in, check the communication and network settings. Also consider temporarily disabling any virus scanners or firewalls to be sure that the data stream isn't blocked.

To start the 'Communications Monitor' for this plugin, select 'Preferences…' from the 'Options' main menu. In the window that appears, select the 'Devices' tab. Next, locate the 'Hydromagic NMEA0183 Plugin #x' item in the list, and right click to get the context menu. In the menu that appears, select 'Monitor Device...'.

Monitor the Hydromagic NMEA0183 plugin

Monitor incoming UDP packets using WireShark

When no data is coming in, and you are able to reach the web-interface of the Serial-To-Ethernet converter, UDP packets might be blocked or malformed. To investigate all incoming data on the Ethernet port connected to the Moxa device, you can use the WireShark freeware software (www.wireshark.org).

After installing and running the software, locate the "Capture" section and enter "UDP Port 4001" in the filter entry box. In case you are using TCP or another port number, you have to adjust this filter, for instance: "TCP Port 10110". Next locate the Ethernet adapter the Moxa device is connected to and double click it, in our case it is the "Ethernet" adapter. The software should now start capturing incoming UDP data.

Capture UDP packets on TCP/IP port 4001

When packets are displayed, wait for about ten seconds, and click the "Stop" button. You can now scroll through the packets to see if they contain NMEA0183 sentences. The screenshot shows a selected UDP packet which contains a complete NMEA0183 (GGA) sentence. When no packets are showed, please disable your firewall to see if this helps. When an Wireless access point or router is connected between the Moxa device and the Hydromagic PC, make sure that the AP or router is in the same IP address range as your computer and Moxa device.

Incoming UDP packets containing NMEA0183 sentences