Specifications

When changes are made, press Enter to confirm them or press Escape to discard any changes and

exit Edit mode.

The Technical Reference section lists all commonly used Talker IDs and Sentence Formatters. This

list can be a useful aid while setting up the sentence filter.

The following buttons are available to edit the list:

Store List Stores the list from MPX-Config into the multiplexer. This overwrites the list in the

multiplexer.

Capture Enables capture mode. The list will be filled automatically with NMEA sentences

that are received by the multiplexer.

Add Add a new rule. Type the desired sentence address into the edit box next to the

Add button and click on Add or press the enter key. This will enter a new rule

with all inputs disabled and all outputs enabled. The input is case-insensitive;

every entered sentence address will be converted into uppercase. The input must

contain 5 characters, including dashes. Numbers are also allowed.

Delete Delete a rule from the list in MPX-Config. Select the entry to be deleted by clicking

on the address in the Sentence column (‘--GLL’ in the example) and click on the

Delete button.

Default Action This determines what happens when a received sentence is not found in the

filter/routing list. It can be set to pass or block such a sentence.

Clear List This button clears the list in MPX-Config (not in the multiplexer!). To clear the list

in the multiplexer, click on the Store button after clearing the list in MPX-Config.

Filling the list

The filter rules can be entered in two ways, manually and automatically. You can add individual

sentences to the list and set the desired routing information. You can also fill the list automatically

with the Capture button. All controls will be disabled during capture and the Capture button

changes to Stop. Leave the capture mode running for approximately 10 seconds. By that time, all

connected instruments will have sent NMEA sentences. Click on Stop to end the capture mode.

It is very important to realize that using capture to fill the list overrides the default routes since

every sentence is in the filter list. It is therefore absolutely necessary to review and modify the

routing settings for each sentence to prevent massive buffer overflows! It is often best not to use

the filter at all if you don’t need sentence-specific routing. Use the filter with care!

Operation

When the multiplexer receives an NMEA sentence, it searches the filter list for a match. The order

of filter rules in the multiplexer is exactly the same as shown in MPX-Config. When a match is

found, the input on which the sentence was received is checked against the input settings in this

rule to determine whether the sentence may be passed or not. If the input matches, the sentence

is routed to the outputs that are enabled.

If no match is found, the Default Action determines what happens next: when set to Pass, the

received sentence is passed and the default routes are applied. When it is set to Block, the

sentence is blocked.

The default routes are set in the Input Settings section on the NMEA Inputs/Outputs page.

Please note that the multiplexer will not pass any sentence when the filter list is empty and the

Default Action is set to Block.

It is important to know that when a Talker ID is set for an input, it is applied to incoming NMEA

sentences before the sentence filter processes them. A filter rule must therefore contain the right

Talker ID.