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ba_aed104_8_e.doc
Stop bit:^
1
AD104 – R5
Y6 -Ub
Y5 -GND
Y12-TRG
Y10-TA
Y8 -RA
Y9 -TB
Y7 -RB
Fig. 5.3.1:
AD104-R5 for 4-wire bus mode (PCB connections)
1.
Long lcable lengths (up to 500m) can be achieved with the aid of the RS485 bus drivers.
2.
The bus mode of the AED is designed as master-slave configuration, whereby the AED implements a
slave. Thus all activities of the AED are initiated by the control computer. Each AED receives its own
communication address (00 ... 31) and can be activated through a select command Sii (ii= 00...31). A
broadcast command (S98) is implemented for certain cases of communication. This means that after such
a command, all AED execute the command of the master, but no AED answers. All commands of this
communication as well as corresponding examples are described in Chapter 7.
Figure 5.3.2 shows the connection of the bus to the RS232/RS485 Converter
(HBM Ordering-No. 1-SC232/422A).
Figure 5.3.3 shows the RS485 bus connection.
The terminating resistors of 500 ohms drawn in Figure 5.3.3 for the electrical function of the bus system are
important. These resistors protect the quiescent-signal levels for the receivers on the bus line. The master line
may be terminated with these resistors in this case only at the line ends. The master and the AED with the
address 31 should contain the terminating resistors for the local distribution of the bus connections shown in the
Figure. The AED contains these resistors already. These can be activated by the command STR1 (these
terminating resistors are switched off on factory delivery). These terminations may not be activated more than
twice in one bus.
The HBM interface converter also includes these terminators.
External trigger signal:
Quiscent-signal level:
TRG= 0V (Low)
Active measuring:
TRG= Low-High edge (0V...5V)
If the external trigger is not used, the input remains open.