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Press Enter or click with the cursor: This enters Edit mode with the text selected and the cursor at
the end. Any character or number that is typed now will erase the existing text entirely unless the
cursor is moved around with the mouse or arrow keys. This will unselect the text.
●
Double-click on the entry. This enters Edit mode the same way as pressing Enter or clicking it for the
second time.
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 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! Simply capturing the list and storing it unmodified is useless and can lead to
unforeseen problems!
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 default
routes are applied. When it is set to Block, the sentence is always blocked.
The default routes are set in the “Input
Settings” section on the “NMEA Inputs/Outputs”
page. 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 correct
Talker ID.
