Figure 6 shows the property sheet for an example OpcDaClient.
As shown in the figure above, OpcDaClient properties can be categorized into three groups:
An OpcDaClient has typical device-level status properties (see “Device status properties” in the Drivers Guide). The following notes apply:
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Status
Status of OpcNetwork communications to this OpcDaClient. Possible status flags include:
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ok - Normal communications, no other status flags.
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disabled - Enabled property is set to false, either directly or in OpcNetwork. While status is disabled, all child Opc points have disabled status; OpcDaClient polling is suspended.
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fault - Typically a licensing issue, if seen.
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down - Error communicating to the OPC server. If status was previously ok (without changing OpcDaClient configuration), this may mean the server host is now unreachable, or the server program is not running.
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Enabled
Either true (default) or false. Can be set directly or in parent OpcNetwork. See Status disabled description above.
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Health
Contains properties including timestamps of last “ok” time and last “fail” time, plus a string property describing last fail cause.
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Fault Cause
If status has fault, describes the cause.
As in other driver networks, the OpcDaClient has an available “Alarm Source Info” container slot you can use to differentiate
OpcDaClient alarms from other component alarms in the station. See “Device Alarm Source Info” in the Drivers Guide for more details.
In addition to common status properties, each OpcDaClient has the following unique configuration properties:
These properties are included when you or an OpcDaClient from the Opc Device Manager (see Figure 4), in addition to being on its property sheet view (Figure 6).
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Address
This is the IP address or hostname of the OPC server.
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Class Id
This is the Windows class ID, or CLSID, of the OPC server instance. It is set automatically when the server is discovered, and is only needed for remote servers.
If the OPC server does not support discovery, you must manually enter its CLSID here.
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Description
(Informational only) On a learned OPC server, this is typically populated with descriptive text.
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Local
Set to True if the OPC server is on the local Niagara platform, or False if on a remote host.
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Use Version Independent Program Id
This is for local servers. Set to True to use the versions independent Program ID. It might be desired to connect to an older version of the server, in which this case, set this to False.
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Program Id
Either this or the Version Independent Program Id are needed to connect to local servers.
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Version Independent Program Id
Either this or the Program Id are needed to connect to local servers.
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Poll Scheduler
See OpcPollScheduler.
In addition to device-level Config properties, each OpcDaClient has the following unique (read-only) status properties about the OPC server and its Niagara client connection. These are visible from the property sheet of the OpcDaClient (Figure 6).
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State
The current client state, as either: Attached, Attaching, Detached, or Detaching.
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Server State
From the Monitor (ping) result, provides the current server status as one of the following:
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Running — Server is running normally.
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Failed — A vendor-specific fatal error occurred within the server.
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No Configuration — Server is running, but has no configuration information loaded. Thus, it cannot function normally.
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Suspended — Server has been temporarily suspended, and is not receiving or sending data.
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Test — Server is in test mode. Outputs are disconnected from the real hardware; but the server otherwise behaves normally.
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Communications Failure — Server is running properly, but is having problems accessing data from its sources. Expect data items affected by this to have individual fault status.
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Server Current Time
Ping result, as the current time of the server.
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Server Last Update Time
Ping result, the time the server thinks it sent the last data value update to this client.
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Server Start Time
Ping result, as time the server instance started.
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Server Group Count
Ping result, as total number of groups being managed by the server instance.
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Server Band Width
Ping result, the behavior of this field is server-specific. The suggested use is the approximate percent of bandwidth currently in use by the server. Any value over 100% indicates the update rate is too high. The server may also return a value of “0xFFFFFFFF” or 4294967295, if this value is unknown.
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Last Connect Time
The last time the client successfully connected to the server.
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Last Shutdown Request
The last time the server sent a shutdown request to the (Niagara) client.