Service manual Description of the electronics
05.08.03 /Jensen / Rei 34-34-00-645 b
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If the start button is directly connected to this interrupt input, a button is obtained which is only active
when the scale is switched off. It can be fitted under the platform, for instance, so that the scale is
started by briefly stepping on it.
Programming
The DMS modules are equipped with an EEPROM which is controlled via the I²C bus protocol. On this
EEPROM all parameters are stored that can be used to influence the program sequence. For example
the way the weight is displayed or the allocation of buttons. It also stores the coefficients for
determining the weight and data for temperature compensation, e.g. the factors for the polynomial.
Furthermore, the scale can store values to be retrieved when the scale is switched on the next time,
e.g. the weight unit used last.
In order to avoid errors, the EEPROM contents are divided into blocks which are monitored by cyclic
redundancy checks. The hamming distance is 4 so that single errors can be corrected and double
errors are certainly detected. In addition, values which are recalculated when the scale is in operation
can be replaced by default values if an error is detected that cannot be remedied.
Serial bus
To allow the scale to be calibrated and additional modules, such as additional displays, to be
connected, the DMS modules are equipped with an interface to the SeSAM bus.
On this bus the stabilized and non-stabilized supply voltages are available. Via a data and a clock
pulse line all relevant data is transmitted to other modules. A special start line is provided via which the
scale can be switched on or other modules can signal that they want to send data.
Both data and start line are open collectors so that they can be switched to low by all modules.
For further details on the bus, please refer to the relevant documentation.
Fault handling
If faults occur, the SeSAM bus initiates a fault message with the relevant fault code. Furthermore, each
fault message includes the number of the module type on which the fault has occurred and a code
which indicates how long the message is to stay on display and which displays are to be suppressed.
The DMS low end module displays its own fault messages on its LCD. Module type (0 for the low-end
module) and fault number are displayed. The other DMS modules only transfer fault messages to the
bus (module type = 1).
The following fault messages are implemented:
10 20 bit counter overflow
11 Counts out off range
12 Switch-on zero setting out off range
13 Zero tracking out off range
14 Error in the kg value calculation
15 Recalibration error
bAtt Battery voltage too low
21 Error in battery voltage measurement
22 Error in temperature measurement
tEMP
Temperature range exceeded ( < 0°C or > 50°C)
30 General bus error
32 Command buffer full
33 More than 8 slaves detected
40 EEPROM error
41 Incorrect EEPROM access
50 Rom checksum error
51 Menu error
CArd
Invalid Chipcard
OFF Chipcard has scale not released
6x Error in measurement of lenght
Notice : Chipcard is saving now
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