Defining EFM Data Item Units

Measurement data item units are defined in EFM-enabled device template files, using the fmsMaps and gmrMaps sections of the template. Data item units are specified differently depending on the application used; in FMS (CygNet Measurement) a broad selection of units can be defined.

Defining Units for FMS

FMS supports a wide variety of units, and also contains both user- and system-defined unit sets. Once data item units are passed from the EIE to the FMS service, data value conversions can be performed in FMS, and a system-defined unit set can be used if desired.

Before mapping units, determine whether or not the EIE for your device type requires units to be defined in the device template file. Not all EIEs allow units to be set in a device template file. For EIEs that require units to be defined in the template, specify the units for all data items that require units in FMS. This allows those units to be communicated to the FMS service, where data values can then be converted to internal FMS unit sets as necessary.

In the device template file, in the fmsMaps section, associate units with each FMS data item requiring units, in the following ways.

• Include a deid attribute within an FMS data item. The deid refers to a data group element with defined units in a native data group.
• Optionally, for Modbus EFM templates only: Include both register number (regNum) and units attributes within an FMS data item. Use this technique for FMS Events and FMS Alarms data items, when the register is not retrieved in any native data group.

See FMS Data Items Units for information about units supported in CygNet Measurement.

See Configuring Unit Set Definitions for information about FMS unit sets.