7
User Serial Port Commands
7.1 Overview
The asynchronous serial portion the MURS RF modem is used to send and
receive data over the air, as well as to configure the RF modem. In normal
operation, the user sends data into the TxD pin of the user port, and this data
will be sent over the air. Receive data from another RF modem is output to
the user via the RxD pin of the user port. One byte in one modem, gives the
same byte out the other modem. No noise, no errors, no dribble bytes. This
is the normal operating condition of the RF modem.
There also is a configuration mode, where in the RF modem accepts certain
commands via the TxD pin. The commands can be used to change certain
internal parameters of the radio modem.
7.2 Configuration Mode
The RF modem may be put into a “config mode”, by entering a sequence of
characters (+++) or by pulling the hardware /CONFIG pin low.
To Enter the Config mode when using AT Commands -
Using serial communications software, send the 3-character command
sequence “+++” while observing times of silence before [BT (Silence Before
Sequence) Command] and after [AT (Silence After Sequence) Command] the
command character.
The default sequence for entering into AT Command Mode:
The default sequence for entering into AT Command Mode:
The default sequence for entering into AT Command Mode:
The default sequence for entering into AT Command Mode:
1. No characters sent for 1 second.
2. Input three (3) plus characters (“+++”) within one (1) second.
3. No characters sent for one (1) second.
7.3 Reading a Parameter
To read the value of a particular setting, issue the command, with no
parameter. The modem will return the value followed by an “OK”. The
modem response is:
The value in ASCII decimal format.
<CR> <LF> sequence (ASCII 0D, ASCII 0A).
An “O”, “K”, <CR>, and <LF> sequence.
For example, to read the ID of the modem that previously had its ID set to 1234,
issue at ATDT command, with no parameter. The modem will return the current
ID, in this case, 1234.
User
Modem
ATDT<CR>
1234<CR><LF> OK <CR><LF>
