BS EN 17255-2 pdf free download

BS EN 17255-2-2020 pdf free download.Stationary source emissions – Data acquisition and handling systems Part 2: Specification of requirements on data acquisition and handling systems.
6.2.2 Interfaces
6.2.2.1 General
The DAHS shall provide analogue and/or digital communication interfaces.
6.2.2.2 Analog communication
A/D converters of analogue communication interfaces shall meet the following requirements:
— resolution shall be at least 12 bit but a resolution of 16 bit is recommended;
— relative accuracy shall be better than ± 0,1 % of the range (in case of multiple ranges, it refers to every range);
— input range shall be able to handle live zero signals, e.g. analogue signals at 4 mA or 2 V.
The DAHS shall be able to receive hard-wired status signals.
6.2.2.3 Digital communication
Digital communication interfaces shall handle the transmission of input data and associated status
information to the DAHS.
Digital communication interfaces shall provide the following functionality:
— a documented communication protocol providing data integrity, e.g. Modbus, PROFIBUS, OPC; NOTE I Standard communication protocols provide measures for data integrity.
— unique addressing of input data sources, e.g. measuring system, within a system containing the DAHS; NOTE 2 Several meastirands can be related to one address.
— unique allocation of all measurands and all status signals to the address of the input data source;
— transmission of the measured signals with a resolution of the measured signals of 32 bit floating- point number according to IEEE 754;
— control of applying zero and reference materials to the AMS, if QAL3 is controlled by the DAHS;
— status information associated to the measured signals including at least identification of valid measured signal, maintenance of the measuring system and malfunction of the measuring system;
NOTE 3 The distinction between the status of the measured signal and of the measuring system allows in case of multiple-component measuring systems the use of the remaining measured components, when one measured component is disturbed.
— ability to test the digital communication between the DAHS and each input data source.
The manufacturer shall specify in a datasheet for each input data source the interface specific data and procedures to access the data.
6.2.2.4 Sampling rate
Raw data received from any input data source shall be continuously sampled at a rate fast enough to ensure no loss in information. The sampling rate shall, however, never be slower than one sample every 10 s from each individual input data source.
6.2.3 Manual data input
The DAHS shall provide the capability for manual data input for peripheral data.
Peripheral data may be manually entered with a lower frequency provided that it is proven that the value of a peripheral parameter is constant over a longer time period and subject to approval by the competent authority.
The DAHS shall provide the capability for manual data input for other data, e.g. QAL3 data, QAL3 correction factors or event-log entries.
Whenever this data are entered either by keypad or other data media, the DAHS shall record the user ID and changes made into the event log (see 7i). Manual input shall not overwrite automatically transmitted data.
6.2.4 Remote data logger unit
Remote data logger units as part of the DAHS can be used to temporarily store raw data to avoid loss of data if the DAHS processing unit is offline. Data shall be transferred between the remote data loggers and the DABS processing unit by a secure communication protocol.
6.3 Input data processing
6.3.1 Validity of input data
The validity of all input data shall be verified.
The DAHS shall be able to identify failure for analogue interfaces by loss of connection e.g. by broken circuit, or for digital interfaces by loss of digital communication. Input data obtained during these periods shall be flagged as invalid.
The DAHS shall check that the input data values are within the specified measurement range. Input data values outside the specified measurement range shall be tagged as ‘out of range’.
NOTE The AMS is considered to be ‘out of range’ for the time period in which the measured values are above the upper or below the lower limit of the measurement range of the AMS. In this case, the measured values can be used for further calculations, unless stipulated otherwise, for example by legislation.
AMS raw data shall be tagged valid if the AMS input data are valid and the AMS is in a measuring mode, e.g. not in test, service, functional test, failure or similar. Otherwise the AMS raw data shall be invalid.
6.3.2 FIrst level data (FLD)
The DAHS shall be able to form and handle FLD in accordance with the specifications of EN 17255-1.
FLD shall be stored in accordance with the requirements of 6..ñ.
If FLD are determined from scaled AMS raw data, all the scaling factors shall be retrievable.
NOTE Scaling to units includes e.g. a conversion from milliamps (mA) to milligram per cubic meter (mg/rn3), or from Volt (V) to Kelvin (K).
The parameters used for determining the plant status from input data shall be retrievable.BS EN 17255-2 pdf download.