Technical Manual

41
The Radio Interface Task
Note: The values of RSSI have no units, they are arbitrary; however, a value of 85 corresponds more
or less to the maximum value in addVANTAGE, i.e. 8 µV.
4.4.1.2. Querying the Actual Configuration Parameters
You can query an addIT to find out its actual configuration parameters. Typing OWN-
ID, for instance will return the actual ID an addIT answers to (it should be the same
as the one on its label). In addition to OWNID, PMP, SLOT, BL, FREQ and RSSI, the com-
mand VER will return the current software version of the device.
The RSSI commands returns two values: the actual measured value of the RSSI and
the value set as threshold. As noted elsewhere, the threshold must be approximately
30% higher than the actual measured value. The actual RSSI is unstable due to the
channel’s random noise, receiver’s internal noise, and/or to transmissions just tak-
ing place. If the actual RSSI value is consistently higher than the programmed value,
something must be wrong, or the channel is very noisy (however, before re-adjusting
the RSSI threshold, check this with a handheld radio receiver or a scanner).
Other commands available in terminal mode are:
• DUMP addr – displays 256 bytes of the internal EEPROM memory, starting
with the address addr (specified as hex values). Valid addresses for the model
A720 are B600 to B9FF. The last 16 slots of data (for 15 minutes slots, that
makes 4 hours of data) are stored at B900 to B9FF. The remainder are used for
internal configuration parameters or reserved for future use.
• RX – switches the device to receive mode until a key is pressed. This command
is used for trimming or checking purposes.
• XMIT param – switches the device to transmit mode until a key is pressed;
param may be 0 – a 2 kHz tone will be modulated on the transmitted carrier, 1
– a 1 kHz tone will be modulated on the transmitted carrier, T – a mixture of
1 and 2 kHz test tones, or missing – an unmodulated carrier will be transmit-
ted. This command is used for trimming or checking purposes.
• B – sends a broadcast frame and displays all the answers, with the RF levels
recorded for each received station.
4.5. The Radio Interface Task
The A720 is intended only as an end device in a radio network. Following frames are
recognized and serviced by an A720:
• PING – used to check if a device is alive; returns a PONG frame;
• REQUEST – returns a reduced data frame (DATA);
• RSETIO – switches the digital outputs and returns the digital inputs value;
• RDUMP – returns a dump of a block of memory;