Technical Manual

46
Wireless Sensor Interface A720 (addIT™)
} request;
DESCRIPTION
The Request frame is used by a master to request data frames from a remote station.
A remote will answer with a data frame (there are currently two types of data frames:
normal and reduced – the A720 answers with the reduced type – see also “Data” on
page 49).
• init_time represents the actual type to be used by the remote to re-initialize
its local RTC; if its value is time_t NULL (default), then no re-initalization will
be performed;
• req_time is the time for requested data. A remote will search its internal data
buffer for data which has a time stamp that is strictly newer than req_time.
Therefore, if a master will request data with exactly the time stamp previously
supplied by the remote, the later must deliver a newer data slot. If the request-
ed data is too old, the remote will send its oldest data, while if the requested
data is too new, the remote will answer with the newest data it has.
4.5.5.2. Broadcast Answer
ID 2
FORMAT struct {
unsigned char RF_levelOut;
} broadcast_answer;
DESCRIPTION
This is the answer to a broadcast request frame; the RF_levelOut is the level recorded
by the device when receiving the broadcast request frame. An A720 will never send
such frames, but will receive and interpret them depending on the mode it was when
it issued the broadcast request frame (see also “Broadcast Request” on page 47). In
terminal mode, all the broadcast answers will be displayed with their RF levels,
while in connectivity check mode, the LED tool will be activated. This frame is not
routable.
4.5.5.3. Set I/O Request
ID 3
FORMAT struct {
unsigned char DDR;
unsigned char PORT;
} setio_request;
DESCRIPTION
This frame is issued by a master and instructs a remote device to switch its ports to
a certain state, as follows:
• DDR specifies if a port will be set as input or as output; if the corresponding bit
is a one, that port will be set as output;
• PORT is evaluated only for the bits set as outputs; it will set or reset the respec-
tive port according to its value in PORT.
The device will answer with the Read I/O frame.