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ARF868 Radio Modems- Guide utilisateur / User guide version V2.2.3
This function enables sweeping of all channels available on the product in a few seconds. It is activated by the ATT02 command.
The ARF868 modem scans all the channels available and returns the RSSI levels on each of the channels to the UART link in the following form: :
Cxxx=-090dBm<cr><lf>
; with xxx = channel no
Cyyy=-101dBm<cr><lf>
; with yyy = No of the following channel
......
The polling time of a channel is defined as 25ms. The result of this polling may show that some channels are more usable than others in a given
environment.
As a second stage and for a more reliable assessment, we can use the ATT03 command which enables the channel to be listened to over a
longer period:
ATT03<c (channel)><t (polling time)>
With : <c> = Channel no
With: <t> = Polling time in seconds
E.g.: ATT03 529 60 -> Scan of channel 529 for 1 minute. The result returned has the following form:
C529=-087/-096/-101dBm<cr><lf>; i.e. in order: RSSI min. RSSI mean/RSSI max. measured over this period.
4.5. Transmission/reception test
This function enables a communication to be put into operation quickly in the field to check the range limit between two modems with the
defined choices of frequency, data rate, power, etc.
The ATT00 and ATT01 commands enable communication to be established between two modems with a minimum of material constraints.
Sending ATT01 to the receiving modem activates reception and continuous monitoring of the frame transmitted (*). The LED indicator lamp on
the front panel of the modem indicates reception by a short flash for each frame received (every second):
•
Green if the frame is OK
•
Red if the frame is corrupted
Sending ATT00 onto the transmitting modem activates the sending of a predefined 64 octet frame every second, continuously (*).
(*): Caution, in these modes the modem is no longer capable of interpreting AT commands. For this it is necessary to exit the ATT00 or ATT01
test modes by sending the ESC character (value 0x1B). The modem then returns: "O" <cr><lf> if the request is correctly interpreted and repo-
sitions itself on listening for an AT command.
4.6. Repeater mode
The repeater mode allows to extend the coverage of modems ARF868 & ARF169 over long distances or use on smaller distances on sites with
one or more natural obstacles (eg presence of hill or others).
For the implementation of the repeater mode, thank you refer to the application note repeater available on our website.
5. Product Configuration - Command Mode
The command mode is an embedded tool, accessible by the serial link via a terminal (*), enabling the programming of the modem parameters
using a set of instructions called: "AT command set". AT commands are used to read and write the modem configuration registers (see § 5.3
Description of registers)
In the command mode, the radio is deactivated (in reception and transmission), except for the radio test commands (commands ATT00 &
ATT01).
(*): Hercules types
5.1. Command mode input/output
Entry into the command mode is obtained by transmission of a sequence of 3 ASCII characters on the serial link.
By default, the sequence is: « +++ », however the user can choose his own ASCII character by reprogramming on register S214 (see § 5.3
Description of registers).
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