MVME297-128模块控制器
该操作由DriveWindow线程使用非活动项完成。7.1.4在线所有在线值（驱动器状态刷新、项目集窗格中的在线项目等）的处理方式相同，但有几个组，因此有几个DriveOPC线程处理它们。驱动器状态刷新、驱动器面板工具栏、监视器以及项目集窗格中当前可见的项目集都有活动组。当前可见项目集以外的组未处于活动状态。高级信息DriveWindow 2 10-23这些值由DriveOPC线程读取，该线程还调用DriveWindow中的建议接收器。在advice接收器中，缓存值，并将消息发布到DriveWindow线程，然后由该线程绘制值。在线项目在活动组中处于活动状态。7.1.5运行监视器在其他方面，运行监视器的处理方式与所有其他在线项目相同，但DriveWindow中有一个额外的测量缓冲区。高级信息10-24 DriveWindow 2 7.1.6暂停监视器当监视器暂停时，数据仍会收集到测量缓冲区中，但在监视器继续运行之前，DriveWindow中的缓存不会更新。7.1.7写入值始终写入设备。写入的值也被缓存，但质量被标记为不确定。DriveWindow会立即从设备中读取值（如果可以读取），因此很少看到不确定的质量。然而，DriveOPC可能知道项目之间的某些连接（例如，控制和状态项目），其中写入一个项目也会更改另一个项目的值。DriveOPC在其缓存中进行内部更改，这也会导致其他项目的质量不确定，但DriveWindow不会立即对其进行读取。下文中未显示回读，但其执行方式与更新中的相同。7.1.8控制。本地项目控制。本地在DriveOPC中有特殊处理。请注意，并非所有驱动器都有此项。高级信息DriveWindow 2 10-25项目的目的是通过DriveWindow获取和释放控制。当值ON写入项目时，将采取控制。但是，许多驱动器都有一个看门狗，它要求在10秒内刷新ON值，否则驱动器会出现故障，面板丢失。除了正常向项目写入值外，DriveOPC在读取项目时也会在内部写入ON值，逻辑如下：•从设备读取项目（并缓存）。•如果读取值为ON，并且自上次写入ON值后已过0.5秒，则重新写入值ON（并以不确定的质量缓存）。由于DriveOPC在内部读取活动组中的周期性活动项目，因此只要在DriveWindow的项目集窗格中锁定并使项目联机，看门狗就可以保持活动状态。但是，如果您要使用驱动器面板工具栏，当控制被获取时，它也会执行同样的操作，我们不建议将项目也放到项目集窗格中。
The operation is done by a DriveWindow thread using inactive items. 7.1.4 On-line All on-line values (drive status refresh, on-line items in the item sets pane, etc.) are handled the same way, but there are several groups and thus several DriveOPC threads handling them. There are active groups for the drive status refresh, the drive panel toolbar, the monitor, and for the item set currenlty visible in the item sets pane. Groups for other than the currently visible item set are not active. Advanced Information DriveWindow 2 10-23 The values are read by the DriveOPC thread, which also calls back the advise sink in DriveWindow. Within the advise sink, the values are cached, and a message is posted to a DriveWindow thread, which then draws the values. The on-line items are active in an active group. 7.1.5 Running Monitor A running monitor is otherwise handled the same way as all other on-line items, but there is an additional measuring buffer within DriveWindow. Advanced Information 10-24 DriveWindow 2 7.1.6 Paused Monitor While a monitor is paused, the data is still collected into the measuring buffer, but the cache within DriveWindow is not updated until the monitor is continued. 7.1.7 Writing Values are always written to the device. The written value is also cached, but quality is marked uncertain. DriveWindow reads immediately the value back (if it is readable) from the device, so the uncertain quality is rarely seen. However, DriveOPC may know some connections between items (control and status items, for example), in which writing an item also changes the value of another item. DriveOPC does the change internally in its cache, which causes the quality of the other item to be uncertain, too, but the immediate read-back by DriveWindow is not done for it. The read-back is not shown in the following, but it is done the same way as in update. 7.1.8 Control.Local The item Control.Local has a special handling within DriveOPC. Note that not all drives have this item. Advanced Information DriveWindow 2 10-25 Purpose of the item is to take and release control by DriveWindow. When the value ON is written to the item, control is taken. However, many drives have a watchdog, which requires the ON value to be refreshed within 10 seconds, otherwise the drive faults with panel loss. In addition to writing values normally to the item, DriveOPC internally also writes the ON value, when the item is read, with the following logic: • The item is read from the device (and cached). • If the read value is ON, and 0.5 seconds has elapsed since the ON value was written last time, value ON is re-written (and cached with quality uncertain). Because DriveOPC internally reads cyclically active items in an active group, a watchdog can be kept alive just by locking and putting the item on-line in the item sets pane in DriveWindow. However, if you are going to use the drive panel toolbar, which does the same thing when control is taken, we do not recommend putting the item on-line in the item sets pane, too.
