25
Data Communication
Transmission format:
Baud rate
9600
Process asynchronous
Star bit
1
Data bits
8
Parity
none
Stop bit
1
Handshake no
Parameters are programmed and can not be changed!
Time behaviour (timing)
The software protocols shall have to be structured in such a way that very simple
timing rules can be applied:
The data flow within a command should not be interrupted. Pauses of more than 100
ms between the characters of a command will cause the receiver to abort the command
in the process of reception. The protocols have been set up in such a way that an
„echo“ can always be received. If the echo has been received, the next command can
be transmitted immediately.
The typical response time is below 300 ms.
If no echo is used, it is recommended to wait for 1 s between two commands.
The LAI command group
A number of bus-compatible commands are available under the protocol designation of
LAI. The „General guidelines“ of the software protocols are applicable.
In addition, there are the following special features:
LAI command structure
A LAI command is structured as follows:
„[mssilld...dpp\r„.
with:
[
start character 5Bh
1 byte
m
transmitter identifier M (4Dh) for master
or S (53h) for slave
1 byte
ss
slave address 01
2 bytes
i
identifier of the data group
1 byte
ll
length of the data field
2 bytes
d...d
data group
0…50 bytes
pp
check sum
2 bytes
\r
rogue indicator CR (0Dh)
1 byte
The transmitter identifier indicates the direction of the data traffic. All characters in
front of the check sum are referred to as
data field.
The
data group
are the characters
after the seventh byte up to the check sum. The actual data are contained in the data
group. The significance of the data is determined by the identifier and the transmitter
identifier. Below the commands will be referred to according to the identifier of the data
group.