Re: Telemetry EQNS oddity


James Ewen
 

On Sat, Apr 10, 2021 at 12:27 PM Arnold Harding - KQ6DI <kq6di@...> wrote:
 
That site only sends telemetry parameters once a day at 09:03, IF the RF makes it out of this RF hole.  It's also 3 hours each way for me to change parameters, so I won't make a special trip for this.
 

Arnold,

Have you read the information on page 74 of the KPC-3 user manual? You might be able to save a bunch of hours driving, and fuel costs as well.

Remote Access to Your TNC 

You can connect to your TNC from a remote station and change values of your TNC’s parameters. This allows you to add or delete stations from the LLIST, change the size of the PBBS, change the MYCALL and so on, all remotely. Extreme caution must be used when you are accessing your TNC from a remote location. There is no built-in safeguard, and as such it is possible for you to change parameters such that the remote TNC will no longer communicate with you.

In order to change parameters in a remote TNC, the RTEXT in the remote TNC must be set to a text string that will be used as the password string. For instance, you might set your RTEXT to:

RTEXT Code 

The remote TNC must also have its MYREMOTE set to a unique callsign (i.e. WØABC4, or XYZREM). If these two parameters are not set, remote access to the command set of this TNC is not possible. When these parameters are set, you can connect to the MYREMOTE callsign of the remote TNC. 

When the connection is made, the remote TNC will send three lines of numbers. The numbers may look like:

1 1 1 3 4 3 
3 1 4 3 1 3
2 1 1 2 1 3 

You must then pick ONE of these lines and decode the password string. Let’s say you choose to decode line 3 (2 1 1 2 1 3). Rewriting your RTEXT string to make this easier you would have:

Character #: 1 2 3 4
Letter:      C o d e 

Therefore, to gain remote access, you must send the following string:

oCCoCd 

(since small letter o is at position 2, capital C is at position 1, and so on) 

Note that case is significant and spaces are considered valid characters.  

If you fail to properly decode the password, the TNC will send three new lines of numbers. You will be given a maximum of three attempts to properly decode the password string. If you fail in three attempts, the TNC will disconnect you and disable connects to the MYREMOTE for 15 minutes. Also, if you connect to the MYREMOTE and start the password sequence but then disconnect, the penalty timer is in effect for 15 minutes. 

Be careful when using the remote access feature. You can change ANY command in the TNC without restriction, but this can lead to problems. For instance, if you change the INTFACE command to KISS and then send a RESET command, the remote TNC will be placed into the KISS mode and will completely quit talking to the radio! Also, if you connect to the MYREMOTE of a TNC and then issue a command like CONNECT W1ABC, the remote TNC will indeed connect to the station, but there will be no data sent to you from that connection. The connected data would be sent to the serial port of that remote TNC. We urge EXTREME caution when using the remote access! Note also that any command that causes a reset (i.e. NUMNODES, PBBS, MAXUSERS) will disconnect all current users (PBBS, NODE, and YOU). 

One other minor limitation applies to receiving data from the remote TNC. When you give any command, the response is limited to 300 characters so some commands will not fully display their response. If you give the command DISPLAY, the full list will begin, but you will not receive the entire list because of the limitation on this buffer.  


You can read more about the remote access by looking at the RTEXT and MYREMOTE command descriptions.

A searchable PDF copy of the TNC manual can be found here:


Remote access is perfect for a situation like this where there is a minor issue to be corrected, and the time and effort to get to the remote site is significant.

Now, you do have the issue where your remote site does not have reliable RF network connectivity. I can't do much about that, but it is possible to send remote commands in the blind if you can get logged into the unit. You don't have to see the results of your commands as long as you can get the command to the unit.

Building robust reliable networks really helps in situations like this. A network with unreliable connectivity due to intermittent paths between nodes, or overloaded RF network traffic levels can make any type of use of the network poor at best.

James
VE6SRV


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