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Protocol

Modem-M16 Protocol

You can configure the modem by issuing commands over the serial link. Five user-configurable parameters are available:

  1. Communication Channel
  2. Operation Mode
  3. Report Request
  4. Power Level
  5. Parrot mode

Each configuration command requires sending specific characters with a 1-second pause between them, followed by a character that selects the new value. Refer to the relevant section below.

Communication Channel Command

The modem can operate on 12 channels (1 to 12). Two modems must share the same channel to communicate.

Procedure:

  1. Send "c" (0x63).
  2. Wait 1 second.
  3. Send another "c" (0x63).
  4. Within 2 seconds, send one character ("1"–"c") to set the desired channel.
Channel Character HEX-Value
1 "1" 0x31
2 "2" 0x32
3 "3" 0x33
4 "4" 0x34
5 "5" 0x35
6 "6" 0x36
7 "7" 0x37
8 "8" 0x38
9 "9" 0x39
10 "a" 0x61
11 "b" 0x62
12 "c" 0x63

Example (Channel 11): 1. Send "c"
2. Wait 1 second
3. Send "c" again
4. Within 2 seconds, send "b" (0x62)

Setting Operational Mode

To toggle between diagnostic mode and transparent serial mode:

  1. Send "m" (0x6D).
  2. Wait 1 second.
  3. Send "m" again.

The modem will switch modes (e.g., if you were in transparent mode, it will switch to diagnostic).

Setting Power Level

To adjust the modem’s power level (1–4):

  1. Send "l" (0x6C).
  2. Wait 1 second.
  3. Send "l" again.
  4. Within 2 seconds, send one character ("1", "2", "3", or "4").
Power Level Character HEX-Value Avg. TX Power (mW) Typical Max Range (m)
1 "1" 0x31 390 300
2 "2" 0x32 555 600
3 "3" 0x33 790 900
4 (Default) "4" 0x34 1105 1000

Note

Maximum range is highly dependent on environmental factors, including noise levels and line-of-sight conditions between modems.

Example (Set Power Level 3): 1. Send "l" (0x6C).
2. Wait 1 second.
3. Send "l" (0x6C) again.
4. Within 2 seconds, send "3" (0x33).

Request Report Command

In both diagnostic and transparent modes, you can request a report at any time:

  1. Send "r" (0x72).
  2. Wait 1 second.
  3. Send "r" (0x72) again.

The modem will immediately generate a diagnostic report.

Set parrot mode

In parrot mode the modem immediately return the message it just got. This feature can be useful mainly for testing of the modem.

To set parrot mode:

  1. Send "P" (0x72).
  2. Wait 1 second.
  3. Send "P" (0x72) again.

To reset parrot mode:

  1. Send "p" (0x72).
  2. Wait 1 second.
  3. Send "p" (0x72) again.