NMEA4WIFI AP NETWORK You can operate the NMEA4WIFI multiplexer in two modes: AP or Client Station. In AP (Access Point) mode, NMEA4WIFI creates a wifi network and smartphones, tablets or computers connect to this wifi network to receive/send data from/to NMEA4WIFI. In Client Station mode, NMEA4WIFI joins an existing external wifi network and transmits/receives wifi data on that network. NMEA4WIFI always creates its own AP network, even when you set NMEA4WIFI to join an existing network. In this panel, you specify the name and the password of the wifi network that smartphones, tablets and computers should use to join this network. When working as an Access Point, NMEA4WIFI uses IP address and supports DHCP. A maximum of 5 clients can join the network and are assigned consecutive IP addresses (eg ...). Security is WPA2-PSK. Ssid and Password can have a maximum of 15 characters and a minimum of 4 and 8 characters, respectively. When you need to change any setting of NMEA4WIFI you should connect to this network and then write in the navigation bar of a browser to get the page that you are reading now.

If you have already a working wifi network and want NMEA4WIFI to join that network as a Client Station, you should enter here the authentication parameters that NEMA2WIFI should use to join this existing network. Ssid and Password can have a maximum and a minimum size of characters as before. The IP address of the multiplexer on this external network can assigned by DHCP or it can be a static one. In order for the multiplexer to obtain an automatic IP from the network/router you enter 0 in the IP Address text box (this is the default). In order to force a static IP you need to specify it, exactly, on the IP Address text box. Make sure that you enter an unused IP belonging to the DHCP pool of the existing network or router. When the connection to an existing network succeeds, the IP address will be shown here: (X.X.X.X).

NMEA4WIFI has four input serial ports named as P#1, P#2, P#3 and P#4 and one serial output port, named as P#5. The baud rate of serial ports P#1 and P#2 is adjustable between 4800, 9600, 19200 or 38400. The baud rate of P#3 and P#4 can be 4800 or 9600 baud. The baud rate of port P#5 can be 4800, 9600, 19200, 38400, 57600 or 115200. It is important to note that if the baud rate of the output port is inferior to those of the input ports, data may be lost. Also, all data output by P#5 is also output by the USB port of the processor module of the multiplexer. Ports P#1 and P#4 have special modes of operation. If you set USB on the baud rate of port P#1, data from that port is not input from the PCB connector but, instead, it is read from the USB port of the processor module. In that case data is read at the baud rate specified on P#5. The special mode of P#4 is called SeaTalk. If you choose that mode data is assumed to be in the SeaTalk format and it is immediately translated to the Nmea 0183 format. The wide text boxes for each serial ports refer to NMEA0183 sentence filtering. If you do not need sentence filtering, you enter 0 (zero) in these boxes. See below for an explanation about sentence filtering. Data received on the input ports P#1, P#2, P#3 and P#4 can be transmitted by output port P#5 or by wifi either using the UDP port, the TCP port or both.

The NMEA4WIFI multiplexer can send and receive wifi data in a "client/server configuration" where the multiplexer is the server and the connecting devices are the clients. You can can use either the UDP, the TCP or both internet protocols to send and receive wifi data. You turn one protocol inactive by setting its port number equal to zero. Non zero port numbers, either UDP or TCP, should be in range from 1024 up to 65535. By default, NMEA4WIFI uses UDP broadcasting on port number 2000 (compatible with Navionics Sonar Chart Live). UDP broadcasting assures that all the clients connected to the wifi network listening to the specified UDP port number will receive the packets by the multiplexer. You should also set the same protocol (UDP or TCP) and the corresponding port numbers on the connection device(s) that receive/send data from/to the NMEA4WIFI multiplexer. When you use the TPC protocol, you need to specify the IP address of the multiplexer. This address, in the case of AP ONLY mode, is If the multiplexer is connected to an external network you specify the IP address that is assigned by the external network. It is important to note that only one connection with the multiplexer can be active through the TCP protocol but, at the same time, you can have multiple UDP connections. The wide text boxes for each wifi ports refer to NMEA0183 sentence filtering. If you do not need sentence filtering, you enter 0 (zero) in these boxes. See below for an explanation about sentence filtering. Finally you can set what to do with the received wifi data. It can be be transmitted through the serial output port P#5 or through the other internet port.

The 4 input serial ports, the serial output port and the 2 input wifi ports can be set to pass or to block certain NMEA0183 sentences. This is governed by a filtering string of up to 43 characters that you can enter in the wide text boxes for each of the referred to ports. The first character is a number, between 0 and 9. When this number is 0 no filtering takes place. When the number is 9 the input is completed ignored (not even read by the multiplexer). When the number is between 1 and 8, it specifies the number of sequences that are periodically dropped independently of the rest of the filtering string. For example, if that number is 3, it means that on 4 sucessive sequences, one is taken and three are dropped. The second character should be a separator. The characters "-", ".", "~" and others could be used as separators but we will use "-". The third character can only be "A" or "R". "A" means that only the sentences that are referred to in the rest of the filtering string are ACCEPTED by (pass through) the ports. "R" means that only the sentences that are referred to in the rest of the filtering string are REJECTED (blocked) by the ports. Each NMEA0183 sequence is specified by 3 characters inserted between separators. For example, the string "2-A-RMC-GGA-GLL-GRS-GSA" means that only 1 in 3 successive sentences is considered and the considered sequence only passes if it is 1 of the 5 that are specified. It is interesting to note that the shown sequence has a length of 23 characters and specifies 5 sentences. For each additional sentence you need 4 more characters (the separator and the 3 characters). Therefore, in order to specify 10 sentences we need 43 characters which is maximum length of the filtering string. An important note is to understand that the filtering strings for the UDP and TCP ports refer to data input. No filtering takes place when data is transmitted by UDP or TCP.

In addition to the above parameters, you have 2 radio buttons to choose between: (i) working in AP mode only or (ii) also connect as a Client Station. You press the SET button for NMEA4WIFI to accept the parameters in this page. If there are no errors in the parameters, NMEA4WIFI changes its operation to the mode and settings selected. IMPORTANT NOTE: you can use a Windows Programme (or tool) to configure the multiplexer as described in this page. The tool is also very useful to set NMEA 0183 sentence filtering, to update new firmware if available, to test the multiplexer or to record received NMEA 0183 data. Please check www.vela-navega.com/forum to get this programme or to obtain support for the multiplexer.

Pressing the Set Factory Defaults button is the same as an hardware reset of the system. The factory setting uses the following parameters: Mode: Access Point; Ssid: NMEA4WIFI; Password: 12345678; IP Address:; Wifi Protocol: UDP; UDP Port Number: 2000; Serial Port P#1, P#3 and P#4 Baud Rates: 4800; Serial Ports P#2 and P#5 Baud Rates: 38400; Serial Output on P#5: none; UDP Output: P#1 and P#2.

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