
AD104-R2, AD104-R5
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ba_aed104_8_e.doc
Changing the baud rate:
The AED can work with different baud rates. The setting can be changed only through the serial interface with
the aid of the command BDR.
Naturally the baud rate of all connected subscribers should be the same in the bus mode. The following
procedure can be helpful to always certainly set the AEDs in a bus to the wanted baud rate on initialization
(switching on) of the system:
1. Set the baud rate of the master interface to 2400 Bd, 8 data bits,
1 parity bit even, 1 stop bit
2. Output of the command string:
;
(clears the input buffer of the AED)
S98;
(selects all AED on the bus)
BDR9600;
(output of the wanted baud rate)
(wait approx. 150ms)
3. Set the baud rate of the master interface to 4800 Bd, 8 data bits,
1 parity bit even, 1 stop bit
4. Output of the command string:
;
(clears the input buffer of the AED)
S98;
(selects all AED on the bus)
BDR9600;
(output of the wanted baud rate)
(wait approx. 150ms)
5. Set the baud rate of the master interface to 19200 Bd, 8 data bits,
1 parity bit even, 1 stop bit
6. Output of the command string:
;
(clears the input buffer of the AED)
S98;
(selects all AED on the bus)
BDR9600;
(output of the wanted baud rate)
(wait approx. 150ms)
7. Set the baud rate of the master interface to 38400 Bd, 8 data bits,
1 parity bit even, 1 stop bit
8. Output of the command string:
;
(clears the input buffer of the AED)
S98;
(selects all AED on the bus)
BDR9600;
(output of the wanted baud rate)
9. Set the baud rate of the master interface to 9600 Bd, 8 data bits,
1 parity bit even, 1 stop bit
10. Output of the empty command:
;
(clears the input buffer of the AED)
11. Command TDD1; if this setting should be stored nonvolatile.
The output of the semicolon before the S98; command is absolutely necessary, since there can be undefined
characters in the input buffer of the AED which, however, are rejected by the reception of the semicolon, due to
driving the AED with different baud rates.
Important Note
With S98; no AED answers but executes the command.
With the example listed above, all AED on this bus are set to the baud rate of 9600, independent of their
previous setting.
Naturally another baud rate can also be set. Then the wanted baud rates must be provided in the command
BDR and the initialization of the master interface must be changed accordingly.
The baud rate is the transmission speed of the interface. This has no effect on the number of measured values
which the AED determines per second.
A high baud rate simply enables a larger number of AED to be inquired per time unit in the bus mode.