Interrogators shall support and tags shall provide 4 sessions (denoted S0, S1, S2, and S3). Tags shall participate in one and only one session during an inventory round. Two or more interrogators can use sessions to independently inventory a common tag population.
Tags shall maintain an independent inventoried flag for each session. Each of the four inventoried flags has two values, denoted A and B. At the beginning of each and every inventory round an interrogator chooses to inventory either A or B tags in one of the four sessions. Tags participating in an inventory round in one session shall neither use nor modify the inventoried flag for a different session. The inventoried flags are the only resource a tag provides separately and independently to a given session; all other tag resources are shared among sessions.
After singulating a tag an interrogator may issue a command that causes the tag to invert its inventoried flag for that session (i.e. A→B or B→A).
The following example illustrates how two interrogators can use sessions and inventoried flags to independently and completely inventory a common tag population, on a time-interleaved basis:
Interrogator #1 powers-on, then It initiates an inventory round during which it singulates A tags in session S2 to B, It powers off.
Interrogator #2 powers-on, then It initiates an inventory round during which it singulates B tags in session S3 to A, It powers off.
This process repeats until interrogator #1 has placed all tags in session S2 into B, after which it inventories the tags in session S2 from B back to A. Similarly, interrogator #2 places all tags in session S3 into A, after which it inventories the tags in session S3 from A back to B. By this multi-step procedure each interrogator can independently inventory all tags in its field, regardless of the initial state of their inventoried flags.
A tag shall power-up with its inventoried flags set as follows:
The S0 inventoried flag shall be set to A.
The S1 inventoried flag shall be set to either A or B, depending on its stored value, unless the flag was set longer in the past than its persistence time, in which case the tag shall power-up with its S1 inventoried flag set to A. Because the S1 inventoried flag is not automatically refreshed, it may revert from B to A even when the tag is powered.
The S2 inventoried flag shall be set to either A or B, depending on its stored value, unless the tag has lost power for a time greater than its persistence time, in which case the tag shall power-up with the S2 inventoried flag set to A.
The S3 inventoried flag shall be set to either A or B, depending on its stored value, unless the tag has lost power for a time greater than its persistence time, in which case the tag shall power-up with its S3 inventoried flag set to A.
A tag shall set any of its inventoried flags to either A or B in 2 ms or less, regardless of the initial flag value. A tag shall refresh its S2 and S3 flags while powered, meaning that every time a tag loses power its S2 and S3 inventoried flags shall have the persistence times shown in Table Amd.1-16. The value of the S1 inventoried flag shall not change as a result of a persistence timeout while a tag is participating in an inventory round. If the S1 persistence time expires during an inventory round then the tag shall change its S1 flag to A at the end of the round.
除了一些图形以及表格信息，这些就是原话了，求指点 |
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