Seca 334, 335, 336 NEC1 Service Manual

The mobile baby scale with special damping system.

The easy-to transport seca 334 weighs only 6.2 lbs and requires surprisingly little space. The weighing tray has a generous and comfortable design for babies and toddlers. With the large, clear LCD figures and the practical carrying handle which can be used to hang the scale, makes daily weighing very easy. The Breast-Milk-Intake-Function shows the exact amount of milk the baby has consumed.

The seca 334 is available as a standard variety or optional with the seca 400.

Introduction Seca 334, 335, 336 NEC1

The DMS modules are used to determine weights using a load cell with strain gauges. The DMS low end module also accommodates the display and the operating unit. To allow the modules to be adapted to different scales, an EEPROM is integrated which is used to configure the module. A connection to the SeSAM bus (Seca’s Serial Autoconfiguring Multicontroller bus) is provided via which the scale can be calibrated and additional modules can be connecte

Weight measurement Seca 334, 335, 336 NEC1

The DMS modules use load cells with strain gauges in a double bridge circuit as sensors. The entire analog part runs on its own supply voltage. This voltage can be switched by the μC to 3V, 5V or 10V. This voltage is also supplied to the load cells. At full load, they deliver a bridge output voltage of 2mV/V. This voltage is measured by a dual slope a/d converter. The DMS ext module can evaluate up to four load cells which are multiplexed accordingly. Only one load cell can be connected to the other types of DMS modules.

The conversion time is selected so that a new measured value is available every 0.1 s. The resolution of the a/d converter is 0.05 μV/V. If several load cells are connected, keep in mind that the resolution relates to the mean output signal of all the load cells connected. When these measured values are within the expected range, they are converted into a weight value using a third order polynomial. In order to increase accuracy, eight measured values are used to calculate the weight to be displayed. The first value obtained after switch-on is used as the zero point. If the values obtained later on do not deviate strongly from this value, the zero point is corrected in order to compensate for possible drifts. (Please also refer to temperature measurement.)

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