Bus−Scan - HBM WE2108 Serie Referenzhandbuch

Scale electronic unit (NSW)
B. All WE2108 are connected to the bus :
9.4
With the aid of the Bus−Scan described below, the address allocation of the bus can be
determined. This is recommended if the address allocation is not known or problems occur
because of addresses allocated double.
Bus−Scan with the same, known baud rate of all units:
A WE2108 with the output address answers with '?CRLF', since it does not know the com-
mand "X;". If no answer comes after a time of approx. 100ms, then there is no WE2108 at
this address. The output of the semicolon before Sxx; clears the reception buffer of the
WE2108, to create a defined starting condition. If the master receives characters other than
? or reports a framing / parity error, there can be a bus fault or multiple allocation of the
address. The addresses should then be reallocated.
If only a few WE2108 with known addresses are connected, the unallocated addresses can
be left out.
The timeout setting for the interface driver of the master is decisive for the speed of the Bus−
Scan. The command string (; Sxx; X;) requires max. 100ms for processing (with 9600 Bd).
WE2108
Read manufacturing No. of the WE2108 (InFo menu):
1.WE2108: xxxxx, 2.WE2108: yyyyy, ...
Initialize interface of the master (9600 Bd, 8, e,1)
;S98; Output broadcast command
ADR01, xxxxx; Set address for unit 1 (example: 01)
ADR02, yyyyy; Set address for unit 2 (example: 02)
Bus−Scan
1. Initialize master interface with the same baud rate as the WE2108.
2. Check first address with the command string:
;
S00;
X;
3. Evaluation of the answer (see below.)
4. Check second address with the command string:
S01;
X;
5. Evaluation of the answer (see below.)
6. Repetition of the command string with the addresses 02...31:
(Select address)
(Output of an invalid command)
(Select address)
(Output of an invalid command)
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HBM