FieldServer FS-8700-21 Appendix A.1. Using UNVT’s, Appendix A.2. Using NVMin, NVMax etc

FS-8700-21 LonWorks Manual Page 24 of 62

Appendix A. Useful Features

Appendix A.1. Using UNVT’s

UNVT’s are User-defined Network Variable Types and are defined in the configuration file by filling the SNVT_Type field with “UNVT”. The UNVT’s size in bytes should also be added to the UNVT_Byte_Length field and the UNVT’s type number in the UNVT_ID field. Valid UNVT_IDs are 0 and the range 146 to 255. The UNVT_ID value will be substituted with the default value of 0 if the field is left empty. Refer to the example in Section 6.2.3

Appendix A.2. Using NV_Min, NV_Max etc.

The NV_Min_Value, NV_Max_Value functionality were added to stop the propagation of ‘out of bounds’ network variables across a LonWorks network. NV values higher than assigned by the NV_Max_Value field or lower than assigned by NV_Min_Value field will not be sent out on the network or copied to their relevant Data Arrays. If one or both of these fields are not assigned values, limit checking will not be performed on that particular field. This functionality applies only to SNVT's of either Floating point or Integer formats. Refer to the examples in Sections 5.2.6 and 6.3.6.

One or both of these fields can be linked to a configuration network variable update input in order to create an interoperable configuration property. For further information refer to Appendix A.5

Appendix A.3. Throttling Mode

When the Lon_Function field specifies a Throttling Mode Client Map Descriptor the NV_Delta_Value, Min_Scan_Time and Max_Scan_Time fields all need to be assigned values.

When operating in Throttling Mode, a Network Variable’s value will be sampled at the Min_Scan_Time period. If the value differs by an amount greater than or equal to that specified by the NV_Delta_Value field from the previously transmitted value, the NV update will be transmitted. Otherwise an NV update will be only sent if the time since the last update is greater than or equal to the Max_Scan_Time field value. Refer to the examples in Sections 5.2.6 and 6.3.6.

This functionality applies only to SNVT’s of either Floating point or Integer formats.

Appendix A.4. XIF Generation

After start-up the FieldServer creates a XIF (version 4.0) according to the configuration loaded. This file is called fServer.xif and can be uploaded from the FieldServer using the RuiNet utility.

The FieldServer’s XIF file is internally generated by the LonWorks driver using the information contained in the FieldServer’s configuration file (CONFIG.CSV). It is not possible to download an externally created XIF file using NodeUtil or LonMaker. It is also not possible to download any type of externally created network variables default values file. The FieldServer’s configuration can be changed by uploading and editing the CONFIG.CSV file, and therefore the XIF file must be obtained by uploading it from the FieldServer. Remember that this XIF file will change whenever the configuration file has been changed, downloaded and the FieldServer restarted.

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