The APRS Telemetry Interface
The Digital Channels
The Interface has two groups of digital inputs.
The first group has 8 digital inputs, TTL-level, connected to P19, Digital/Counters. You can choose digital input or frequency counter input by reading the right channel.
You can check the digital inputs via the serial port. Type the command "RD 1" (Read Digital 1) and the interface will send the actual values of the input lines as eight bits, "0"/"1" every second. This testmode does not influence the connection between the interface and DIGI_NED. Type "q" to stop the testmode.
As default setting the digital channels are connected to DIGI_NED-address 7. You are free to change this setting by the channel matrix.
The second group has 6 input bits. Each of these input lines has a second special function.
You can check the digital inputs via the serial port. Type the command "RD 2" (Read Digital 2) and the interface will send the actual values of the five input lines and the result of the comparator as six bits, "0"/"1" every second. This testmode does not influence the connection between the interface and DIGI_NED. Type "q" to stop the testmode.
If you want to read the second group of digital channels by DIGI_NED, you have to connect this channel to a DIGI_NED channel by an "MM"-command first. Bits 7 and 8 are unused and they allways read "0" in DIGI_NED.
Configuration in DIGI_NED
Entry in "digi_ned.ini":
telemetry: 30 1 off,off,off,off,off,lpt1_8/7 DIGI_DEST
This means: Send the telemetry data every 30 minutes via port 1. The analog channels are switched off in the example. The last entry defines the DIGI_NED-address 7 for the digital channels on LPT1 in 8 bit mode.
Query to the digipeater
Send a message "tlm b" to the digipeater.
B1-B8 value 10101010
If you send the message "tlm b1" to the digipeater, you will get
the value of digital input 1.
B1 is hi
The exact format of the output is defined in the file "digi_tlm.ini".