The alarm limits are stored in the PLC. So that the PLC can react. The PLC transfers one bit of information, when the signal lefts the range of the alarm limits.
However for visualisation, the analog values of the alarm limits data must be transfered as digital values from to the HMI device.
Q-DAS "Advanced Quality Data Exchange Format (AQDEF)" - “The AQDEF (Advanced Quality Data Exchange Format) work group was founded to specify a standardized data exchange format, binding requirements for data aquisition and data transfer between measurement system manufacturers and Q-DAS software products”.
It is important that a MES software stores data with timestamps in UTC and not in local time. The problem are daylight savings applied to local time in many countries, including EU: In Spring, you have a gap of one our in your datastream, in Autumn you loose data of 1 hour ( as it is not possible for most MES systems, to store 2 datasets with the same timestamp ).
Oracle "Implementing Temporal Validity" - “Valid time temporal support in Oracle Database enables you to associate a valid time dimension with a table and to have data be visible depending on its time-based validity, as determined by the start and end dates or timestamps of the period for which a given record is considered valid. Examples of time-based validity can include the hire and termination dates of an employee in a Human Resources application, the effective date of coverage for an insurance policy, and the effective date of a change of address for a customer or client”.
SEMI Interface A Standards ( E120, E125, E132, E134 ).
EDA does not replace the SEMI SECS/GEM standards or the SEMI GEM 300 standards, since EDA does not provide any features for equipment control or configuration. Instead, equipment suppliers support EDA in addition to other required interfaces.
The Generic Equipment Model ( GEM ) defines a standard implementation of SECS-II for all semiconductor manufacturing equipment. The GEM standard defines a common set of equipment behavior and communications capabilities that provide the functionality and flexibility to support the manufacturing automation programs of semiconductor device manufacturers.
The PEER Group Inc. "SDR" - “Provides high-technology factories and their equipment suppliers with the connectivity solution required to implement the well established SEMI equipment communication standard (SECS). SDR is fully compliant with current releases of SEMI standards E4 (SECS I), E5 (SECS II) and E37 (HSMS) and is in wide use throughout the semiconductor industry and is considered the standard that other SECS implementations are measured against.”.
The PEER Group Inc. "GEM4Tools" - “SECS/GEM is the communications standard for high-technology equipment. OPC is the communications standard for PLC-based equipment. PEER Group brings SECS/GEM and OPC together to deliver fast and easy factory communications for semiconductor, solar, MEMs, LED and other high-technology manufacturing equipment”.
The PEER Group Inc. "SECS4Hosts" - “The SECS/GEM protocol is complicated compared with PLC-based factory communications. With SECS4Hosts, you can simplify the development of a host-side SECS or SECS/GEM driver. SECS4Hosts is all about speed. It's simply the fastest way to give your Windows host applications the ability to communicate with any SECS-compliant equipment”.
EN.Wikipedia "SECS-II" - “The protocol is maintained by the SEMI organization, from which copies of the SEMI E5 standard may be obtained for a fee”.
GitHub "Microsoft/CDM" - “The Common Data Model (CDM) is a standard and extensible collection of schemas (entities, attributes, relationships) that represents business concepts and activities with well-defined semantics, to facilitate data interoperability. Examples of entities include: Account, Contact, Lead, Opportunity, Product, etc.”.
IT-Zoom "Neue Details zur Open-Data-Initiative", 2019-03 - “Ziel der Initiative ist es, die Kompatibilität der Anwendungen und Plattformen der drei Partner durch ein gemeinsames Datenmodell sowie die Speicherung der Informationen in einem gemeinsamen Datenpool zu verbessern. Der einheitliche Datenspeicher ermögliche es Kunden, nahtlos zwischen verschiedenen Entwicklungstools und Applikationen zur Bereitstellung von Diensten zu wählen”.