16
AR100 Operation Manual
5.1.2
Answer
An
‘
answer
’
is a data burst that can be transmitted by a
‘slave’
during the
course of the session.
All messages with an ‘answer’
burst contain 1 in the most significant digit.
The data in a message is
transferred in nibbles (aka:”tetrads”)
. When a
byte is transmitted, the lower tetrad goes first, and then follows the higher
tetrad. When multi-byte values are transferred, the transmission begins
with lower byte.
When ‘answer’ is transmitted, the message contains:
•
SB-bit, characterizes the updating of the result. If SB is equal to "1"
this means that the sensor has updated the measurement result in the
buffer, if SB is equal to "0" - then non-updated result has been
transmitted (subject to sampling period). SB=0 when parameters
transmit;
•
Two additional bits of cyclic binary batch counter (CNT). Bit values in
the batch counter are identical for all transmissions of one batch. The
value of batch counter is incremented by the sending of each burst and
is used for formation (assembly) of batches or bursts as well as for
control of batch losses in receiving data streams.
The following is the format of two ‘response’
data bursts for transmission
of a byte:
Byte
Bits
Description
7 6 5 4 3 2 1 0
0
1 SB CNT
MSG[0] lo Lower tetrad of the 0
th
byte
1
1 SB CNT
MSG[0] hi Higher tetrad of the 0
th
byte
2
1 SB CNT
MSG[1] lo Lower tetrad of the 1
st
byte
3
1 SB CNT
MSG[1] hi Higher tetrad of the 1
st
byte
…
…
…
…
…
All values are given in binary form. The Base distance and range are given
in millimeters. The value of the result transmitted by a sensor (D) is so
normalized that 4000h (16384) corresponds to a full range of the sensor
(S in mm), therefore, the result in millimeters is obtained by the following
formula:
X=D*S/16384 (mm) (1).
On special request (
05h
), the current result can be latched in the output
buffer where it will be stored unchanged up to the moment of arrival of
request for data transfer. This request can be sent simultaneously to all
sensors in the net in the broadcast mode in order to synchronize data
pickup from all sensors.
To issue requests with sizes greater than one byte, set the high byte
‘session’ then send the low byte request ‘session’.
Refer to Section 10 for a list of all requests and parameters.
