
AD104-R2, AD104-R5
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ba_aed104_8_e.doc
7
Individual descriptions of the commands
7.1
Interface commands (asynchronous, serial)
Characteristic data of the interfaces
Start bit:
1
Word length:
8 bits
Parity:
none / even
Stop bit:
1
Software handshake
(XON / XOFF) is possible
Baud rate:
1200; 2400; 4800; 9600;19200; 38400 baud
The asynchronous interface of the AED is a serial interface, i.e. the data are transmitted bit for bit after one
another and asynchronously. Asynchronous means that the transmission works without a clock signal.
A start bit is set before each data byte. The bits of the word, a parity bit for the transmission protocol (optional)
and a stop bit then follow.
Fig. 7.1.1:
Composition of a character
Since the data are transmitted after one another, the transmission speed must agree with the reception speed.
The number of bits per second is called baud rate.
The exact baud rate of the receiver is synchronized with the start bit for each transmitted character. The data
bits which all have the same length then follow. After the stop bit is reached, the receiver goes into a ‘waiting
position’ until it is reactivated by the next start bit.
The number of characters per measured value depends upon the selected output format (
COF
command) and
can be 2 to 17 characters (see also
COF
command).
The interface must be configured to build up the communication between AED and computer. The following
commands are provided in the AED for this :
ADR; BDR; COF; TEX; S..;
Start
Parity Stop
1 Bit
Word length = 8 data bits
1 Bit
1 Bit
1 character