Historians: What are the features and capabilities of historians?

PreLC

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Hello everyone!

How do historians really work? I have not really attended any vendor training *cough* advertisements *cough*.

What options of historians exist? What is the data replay like? Is it only a textual log, or can this also replay ladder logic/ functional blocks?


Is it worth it really? Our plant already has an MES system for basic error proofing, but not to record all I/O.


Thanks!
-PreLC.
 
I could type it out but... google found this for me (I'm not associated with the linked site)

http://www.automatedresults.com/PI/data-historian-overview.aspx

cliff note version: a process historian that is configured correctly would record meaningful data for analysis and troubleshooting. No, it wouldn't replay logic sequences unless you add a lot of logic to support that, of course.
 
Hello everyone!

How do historians really work? I have not really attended any vendor training *cough* advertisements *cough*.

What options of historians exist? What is the data replay like? Is it only a textual log, or can this also replay ladder logic/ functional blocks?


Is it worth it really? Our plant already has an MES system for basic error proofing, but not to record all I/O.


Thanks!
-PreLC.


I think data replay is a feature of SOME historians, but it far from a standard feature. It would require a lot of bandwidth to record ALL IO in a system.


Also, if the advertisements come with lunch, or at least donuts, it isn't so bad. If you vendor wants you to pay for training before you make purchasing decisions, you might want to look elsewhere, but this sounds like a great opportunity to have a couple different sales guys come in, drop off keychains/pens/coasters/whatever, and get your team free lunch all week!
 
The purpose of a historian is not to record all I/O in a system but rather important I/O, Parameters and other data critical to the process.

For example cycle times, Oven temp setpoints and actual values. An example of an I/O point may be a counting sensor or a start button that starts a cycle or a stopped timer that keeps track of downtime, etc. When the zone six temp setpoint was changed what time was it changes and what operator login changed it?

An MES system will provide and track data about a product or batch from the start to the end of the process and is more for quality, Traceability, Material Management, etc.

You may see a Historian and MES in the same environment but normally the Historian is more of a granular window into the process where the MES is more high level and a large part of the overall ERP system.
 
Typically the historian will display the data you set up to track in a basic time/value trend, many also have report funcions and use Excel to make advanced reports on data pulled in.

I track thousands of meaningful tags in our historian from multiple processing lines. All kinds of stuff, speed settings, auto/manual status, motor/valve logic status, temperatures, flow rates, PID Loops PV,SP,CV. Recipe settings, you name it, I track it.

It has taken some time to get there, learning what exactly to track in the historian. We also have a large fault memory on our HMIs for at least a few days worth of alarm history.

It comes in handy many times trying to figure out what happened hours earlier. For example, Boss says: can you tell me why we ruined a batch of XXX product on 3rd shift? Well the cook process was put in manual and the batch did not get to the correct temperature.
 
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There's no point storing data if you're not going to look at it.

Most historians require someone to define what is to be recorded in them. Because of price, not everything is recorded by default and only the really important parameters.
The thing I noticed before and changed where I currently work with almost immediate benefits was making the historian data accessible to everyone on site via the web interface on PRoficy Historian (this is not an advert, I hate GE's offering in the SCADA world, but have to live with it).
When people wouldn't be bothered to look into the production processes, they now have an interest and several inefficiencies or problem were picked up from it.

I did work for a company in a very high stakes industry that created a blackbox for their control systems that records everything that is communicated across their network and can analyse (typical historian trends with calculation functionality) and playback (basically displays what the operator was seeing in his screens when he was operating the equipment). It was both the most incredible product they sold and the most hated one by the operators.
 
So what is the difference between a Historian and a SCADA system? Is a Historian just part of a SCADA system? Is Historian a fancy word for a datalogger(probably conceived by the marketing department)?
 
SCADA system is what let's you see and control your process. This has evolved over time and it now reaches from the manufacturing planning all the way to the operator screens.



Historian can be much more than a datalogger as it can store not only analog data, but also alarm data. However, its function is to log data.
 
A true historian is generally something that handles data from all over the plant, not just one line.


It also allows for historical tags to be added, scan times modified, and deleted without interrupting the actual historian (no stopping and starting).


A true historian also handles much more data typically then a datalogger built into an HMI/SCADA platform, and in a unified manner.


Also, expect to have a decent, dedicated database server.
 
Typically, to be called a process historian, it has to have ability to compress and filter data. A data logger on the other hand, record data on a time poll and records everything.

The dominate player in the process historian world is OSI PI. They have all their training video on Youtube if you want to learn more. Rockwell's FactoryTalk Historian SE is rebranded OSI PI.
 

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