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4.4.4.Map Descriptor Example #1 – CALR Report.
To be useful to the upstream device the driver reports gas concentration values and gas names from the QLA report. In reporting the gas names it is most useful when a driver stores an index value which is used to imply the gas names. The reason this is most useful is that it is typically easier for automation devices to work with numbers and not text.
When the driver reads the Calibration report, it does two things.
1)It stores a string of gas names vs. index values in the Data Array. This string can be viewed using the Ruinet Utility and may be of help in interpreting the gas name index values stored by the QLA report.
2)The data is stored internally by the driver and when a QLA report is parsed the driver looks the gas names up in the CALR report data and uses the lookup to determine what gas name index value to store.
//Client Side Map Descriptors
| Map Descriptors |
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| Map_Descriptor_Name, | Data_Array_Name, | Data_Array_Offset, | Function, | Node_Name, | Address | Length, | Scan_Interval, | TGM_Funtion |
| RD_CALR, | DA_CALR, | 0, | RDBC, | Node_A, | 0, | 100, | 600s, | CALR |
Although | not | Data | storage | |
starts | at | this | ||
mandatory | it is | location | in | the |
recommended | Data Array. |
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that each MD is |
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given a unique name.
A list of gas names vs. index values is stored in the Data Array specified here.
In this particular example, the list is stored as an ASCII string and hence it makes most sense to ensure that the Data Array’s format is BYTE so that it can be viewed as a string when using Ruinet.
Tells the driver to repeat this | Reserve | enough | Tells | the | driver | ||
read task continuously. The | space | in | the | Data | to | read | the |
polling interval is set by the | Array | to | store | the | Calibration |
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Scan_Interval parameter. | gas/index string. |
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For the CALR report is may |
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also make sense to use the |
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‘ARS’ function which gets the |
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| No | need | to |
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driver to read this data once |
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| read | this report |
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each time the driver restarts. |
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The node name connects the Map Descriptor to a Node definition which in turn is connected to a port. That is how the driver knows which port to use to poll for this data.
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