Peripheral Devices
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It might seem odd to write to the Cycle Data, Event and Trace queues but by writing a two-byte integer to
one of the corresponding address you can control the queues as follows:
Skips reading of the current data item in the data queue. Next read will return next data item (or the
first part of it) in the queue.
Flush the data queue. All items in the specified process data queue are deleted. However, the data
item currently being read will not be deleted. It can safely be read also after that this command has
been issued. To remove the current data item you have to issue a skip command.
Rewind the data queue to the oldest value data item available in the central SRAM storage.
Here value is interpreted as an earlier received device specific sequence number (DataNo) to which
the queue should be re-winded.
When the queue is read the next time the item that corresponds to DataNo = Value + 1 will be
returned, if it exists in the queue.
If it no longer exists in the queue then the item returned will have DataNo set to Value + 2 to indicate
this.
For Event and Trace the DataNo is always included in the item read. For Cycle data you must
include it manual using the reporter for this .
Note! If the external communication device is added to a TC that also have an API device then the PLC
data area will be shared with corresponding area used by the API, Application Programmers
Interface. If you use these simultaneously you must co-ordinate the use of the cells to avoid
unwanted collisions.
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