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PostedThursday, September 2, 2021 at 1:32 AM
Industrial Internet of Things (IIoT) applications’ data accuracy and reliability are highly dependent on the uptime of several factors. Many solutions work perfectly well under normal circumstances, but only those systems designed to anticipate and respond to failure are appropriate for industrial applications.
Deploying Open Automation Software as an Edge solution can help to avoid data loss and downtime due to communication breakdown, database failures, network loss, and application errors. First, let’s take a look at a typical end-to-end industrial application and all of the possible points of failure. In this example, the system consists of a data source, PLC, data server, database, and finally an application or HMI reading data from the data server. Each component and connection is a potential source of failures.
(1) Data Source
Industrial equipment generating data or being controlled
a logic controller collecting and tracking data from the source
(5) Data Server
Software used to monitor, log, and expose data to external applications
the location of historical data logged by the Data Server
(10) Application or HMI
An interface intended to present the data to end-users for monitoring and control
All communications channels between system components
Now, let’s explore all of the possible ways a system can fail and how using the OAS Platform as your Data Server can mitigate these failures. In most cases, OAS can even prevent data loss and increase availability of data to end-users.
Equipment can be down due to scheduled maintenance or components of the physical systems can fail causing production to be stopped.
In the case of instrumentation failure the sensor data will be in error...
In the case of instrumentation failure the sensor data will be in error and will be collected with bad quality flags, indicating the data is not reliable and should not be used.
PLCs and controllers can lose power without a backup power supply in place, or can be set in offline mode to update control programs.
A failure in network communications to the controller or OPC server can cause a loss of data during production.
Open Automation Software (OAS) can disable and enable communications based on data quality or from other independent signals using the property Enable Communications from Tag.
To account for equipment or sensor failure redundant equipment should be in place as alternate data source.
OAS has the ability to automatically switch or override a data source with the property Source When Bad to one of the 4 following options.
OAS has built into each driver interface the ability to define a failover IP address or url to account for failures in communications with Modbus devices, Siemens S-7 controllers, Allen Bradley PLCs, MQTT Brokers, AWS IoT Gateways, MTConnect data streams, OPC DA Servers, and OPC UA Servers. Read more about Driver Interface Failover and how to easily setup automated communication backup.
The OAS data historian has built in handshaking support to obtain buffered data within the controller and pass back confirmation for data synchronization with the controller. Read how to Log Buffered Data from a PLC or Controller which is also applicable for OPC DA and OPC UA Servers as well.
A server hardware or network failure can cause a data server to become unreachable.
Some IIoT gateways do not permit online changes, possibly due to a custom application that needs to be compiled, or long delays can be caused during software updates.
OAS can be deployed in parallel for as many redundant servers as desired, each having the same configurations with the ability to automatically enable or disable communications, archiving, and notification based on which server is the master. Read more about OAS Redundancy.
OAS permits changes to all configuration attributes while a system is operational eliminating the need to take a system down. OAS supports manual, CSV import, and programmatic updates via .NET or REST API. OAS also has built Automated Update feature to upgrade OAS platform reducing downtime for a complete update.
Uptime is critical in data archiving to build accurate data models, maintain faultless production data, and validate operations performance. Logging data remotely can cause a loss in data if the data historian does not have data buffering to account for temporary loss in communications to the database engine.
Valid IIoT data collection systems work on a first-in-first-logged order or processing, but can get behind when there is a burst of data to log, often leading to a loss in data.
Database Store and Forward
OAS data logging and alarm logging have Store and Forward built into the buffer data to a local disk for as long as the database engine is not reachable. See OAS Store and Forward in action in the 10 Things Your Data Historian Should Do video.
OAS implements the most efficient methods to insert records to a database providing database engines to run remotely being able to insert over 1,000,000 records per call. See Data Historian Performance Benchmarks comparing SQL Server, Oracle, mySQL, MariaDB, PostgreSQL, MongoDB, and SQLite, MSSQL providing the best performance with OAS logging over 2,000,000 values per second. OAS also support more than 10,000 logging groups per server each logging to a separate table.
During network failure between the client application and the server can leave operators and supporting applications operating without the information needed to make informed decisions.
Client application failures can leave operations personnel and production managers void of the data needed to operate safely and reliably.
All OAS .NET assemblies for programmatic interface and visualization support Client Application Failover to automatically switch from primary server to backup server on network failure or signal failure.
OAS is deployed in Distributed Network Architecture to support unlimited client applications per server.