Driver attributes
Each driver is enabled by a feature line (element) in the license file. Most of the drivers use the same attributes within that feature.
The most common driver attributes are:
<feature name="driverName" expiration="expirationDate"
device.limit="none" history.limit="none" point.limit="none"
schedule.limit="none">The various limit attribute values
can be either "none" or a numerical (limit) value,
for example device.limit=32. A limit value of none means unlimited, whereas a limit value of 0 means none allowed.
For many drivers, only the point.limit and device.limit attributes are applicable; yet
most drivers include all .limit attributes. For example,
due to the simplicity of the Modbus protocol, none of the Modbus-related
drivers have any history or schedule import/export capability. Thus, history.limit and schedule.limit values
have no significance in the feature for a Modbus driver.
In Niagara 4, and depending on the license, limit attributes in individual drivers may be superseded by global capacity limits using a licensing model that sets limits, which span across multiple drivers. This allows more flexibility to allocate the number of devices, points, and so on—without requiring ongoing license changes.
| Attribute | Description |
|---|---|
| name | Defines the name of the driver, often the same as the actual module (.jar file) name, for example: bacnet, lonworks, etc. |
| expiration | Defines the date when the driver expires. This is, typically, the same as the expiration property of the license feature. In some cases, such as beta testing agreements, individual drivers may be set to expire even though the main license file is non-expiring. |
| device.limit | Designates a license limit on the number of devices that may
be added to this specific driver network in the station database.
Above this limit, any added device component (and all its child components)
are in fault. This limit has no impact on the actual physical limitation of a field bus. For example just because the lonworks feature is set to device.limit="none" does not mean that you can exceed the normal limit of 64 devices per segment. |
| history.limit | Limits the number of histories that can be imported from remote histories (logs or trends) into the station's history space, and/or exported from station histories to appear as histories in remote devices. Above this limit, any added history import descriptor (or history export descriptor) is in fault, and the associated import/export is not successful. |
| point.limit | Eesignates the maximum number of proxy points that may be added to the station database for a particular driver. Above this limit, any added proxy point are in fault. |
| schedule.limit | Limits the maximum number of schedules that can be imported from remote schedules into the station’s database, and/or exported from station schedules to appear as schedules in remote devices. Above this limit, any added schedule import descriptor (or schedule export descriptor) is in fault, and the associated import/export is not successful. |
| parts | This is an alphanumeric part code is automatically assigned when generating the license file and is for internal use. |