The terms 'Raw Data Channel' and 'Calculated' or 'Virtual Data Channel' are commonly-used terms in FlowWorks.
Note: Please familiarize yourself with the inherent differences between the two - they both have very specific purposes!
Raw Data Channel
- A stream of data points whose source is an instrument in the field or an imported data file. Essentially, Data Channels are considered 'raw' when they contain unmodified data, that enters FlowWorks' system.
Put simply, a Channel is a source for data. That data could be the rate of flow, it could be the inches of rain, or it could be the voltage coming from a battery. This data is collected and the value along with the date & time stamp is forwarded to FlowWorks. When you report or graph (as seen in the image below), the data, is associated with the Site or origin and made available for reporting and analysis.
The type of data contained in a Raw Channel is totally dependent on the sensor or meter in the field. The units displayed are those defined to FlowWorks when the Channel is configured.
The Channel name displayed in FlowWorks may be limited by the communications methodology used to forward this data to FlowWorks. A portion of the system security tests require that the data arrive bearing the configured Channel Name. Thus, if you are conveying your data by FTP, the displayed Channel Name is going to be the same as that contained within the data packet. If your data comes from a Telog logger, there is some ability to map the Telog Channel Name to a FlowWorks Channel Name providing the ability to display in FlowWorks a name more recognizable by your users. Other instrument manufacturers and even differences within the models of a manufacturer may enhance or limit your ability to create unique Channel Names. For the most part, users have traditionally chosen to use the names commonly generated by the field equipment.
There is a common workaround, that enables you to have a desired Channel name: it entails using FACE to configure a Virtual Channel with the Channel name you want, and then copying in data from the original Raw Channel. Any new data is automatically logged in both the original Channel and in the Virtual Channel, so you only need to perform setup once. This method does not modify the raw data in any way - it simply allows you to reference the data in a Channel that has a recognizable name. To learn how this is achieved, see topic titled, "Example: Making a Copy of a Channel".
Calculated Data Channel (Aka Virtual Channel)
- A virtual stream of data points whose source is a Raw Data Channel to which F.A.C.E. math, F.A.C.E. conditional statements, and/or F.A.C.E. functions have been applied to adjust data originating from a Raw Channel; or to create information which was not directly available from the field instrument (such as flow when the instrument only supplies depth and velocity).
It is important that FlowWorks does not support modifications to data originating from Raw Channels, for the necessity of maintain a working backup of raw data that can be easily referenced. Thus, using FACE, users create a new Calculated Channel that consistently copies-in data from the original Channel and applies a desired conversion function or formula. The resultant data in the Calculated Channel can be used in any for any form of analysis in lieu of the original Channel, thus leaving the original Channel untouched in case a back-up is ever needed. Just as with Raw Channels, Calculated Channels can be used in all FlowWorks tools, including Graphing, Reporting, Monitoring & Alarming.
To find out how to create a new Calculated Channel, see topic, "Creating a Calculated Channel".