System and method for selecting a subset of autonomous and independent slave entities

• US 6,812,852 B1
• Filed: 10/27/1998
• Issued: 11/02/2004
• Est. Priority Date: 09/09/1994
• Status: Expired due to Fees

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Cesar, Christian Lenz
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): YANG, CLARA I
• Application Number:
  US09/179,481
• Time in Patent Office: 2,198 Days
• Field of Search: 340/825.69, 340/3.51, 340/3.52, 710/110, 710/111
• US Class Current: 340/4.3
• CPC Class Codes: G05B 19/0421 Multiprocessor system
• CPC Class Codes: G05B 2219/2231 Master slave
• CPC Class Codes: G05B 2219/25277 Tristate
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 2201/20 Binding and programming of remote control devices

Abstract

A master entity is capable of broadcasting commands to a plurality of three-state-selection machine slaves. Transitions from one state to another are effected on instruction from commands in a sequence of commands broadcast from the master. Slaves move to another state when they satisfy a primitive condition specified in the command. By moving slaves among the three sets, a desired subset of slaves can be isolated in one of the sets. This desired subset of slaves then can be moved to one of the states that is unaffected by commands that cause the selection of other desirable subsets of slaves.

Claims

1. A state machine slave comprising:

three or more states, being at least a first state, a second state, and a third state, the slave being initially in the first state;

a memory with one or more stored information values;

a receiving unit for receiving one or more commands in a command sequence, each of the commands specifying a “

transfer from state”

, “

transfer to state”

, and a primitive condition; and

a processing unit that causes the slave to move to the second state being the “

transfer to state”

if the first state is the same as the “

transfer from state” and

one or more of the information values satisfies the primitive condition, the slave being moved to the third state by another command in the command sequence only if the slave is in the second state, and the slave, once moved into the third state, remaining in the third state.

2. A state machine slave, as in claim 1, wherein the first and second states reverse roles after an end of one or more subsequences in the sequence of commands.

5. A state machine slave, as in claim 1, where the second and third states reverse roles after an end of one or more subsequences in the sequence of commands.

6. A state machine slave, as in claim 5, where the second and third states reverse roles at the end of each subsequence corresponding to a term in a sum of left-nested expressions.

7. A state machine slave, as in claim 6, where the sum of left-nested expressions is a sum of products.

8. A state machine slave, as in claim 1, where states cycle roles as follows:

the first state assumes the role of second state, the second state assumes the role of the third state, and the third state assumes the role of the first state after an end of one or more subsequences in the sequence of commands.

9. A state machine slave, as in claim 8, where the first, second, and third states cycle roles at the end of each subsequence corresponding to a term in a sum of left-nested expressions.

10. A state machine slave, as in claim 9, where the sum of left-nested expressions is a sum of products.

3. A state machine slave, as in 2, where the first and second states reverse roles at the end of each subsequence corresponding to a term in a sum of left-nested expressions.

4. A state machine slave, as in claim 3, where the sum of left-nested expressions is a sum of products.

11. A system comprising:

two or more slaves, the slaves comprising;

three or more states, being at least a first state, a second state, and a third state, the slave being initially in the first state;

a memory with one or more stored information values;

a receiving unit for receiving one or more commands in a command sequence, each of the commands specifying a “

transfer from state”

, a “

transfer to state”

, and a primitive condition;

a processing unit that causes the slave to move to the second state being the “

transfer to state”

if the first state is the same as the “

transfer from state” and

one or more of the information values satisfies the primitive conditions, the slave being moved to the third state by another command in the command sequence only if the slave is in the second state, and the slave, once moved into the third state, remaining in the third state; and

one or more masters for communicating the commands to all the slaves and determining the sequence of commands in order to select a subset of the slaves that satisfy a condition.

12. A system, as in claim 11, where the master is a base station, the slaves are radio frequency tags and the base station communicates with the radio frequency tags with a radio frequency signal.

13. A system, as in claim 11, where the one of the subsequences in the sequence of commands moves one or more first sets of slaves from the first state to the second state, then moves one or more second sets of slaves from the second state to the first state, and then moves the slave remaining in the second state to the third state.

14. A system, as in claim 11, where the one of the subsequences in the sequence of commands moves one or more first sets of slaves from the first state to the second state, then moves one or more second sets of slaves from the second state to the first state, and then moves the slave remaining in the first state to the third state.

15. A system, as in claim 11, where the one of the subsequences in the sequence of commands moves one or more first sets of slaves from the first state to the second state and then moves the slaves in the second state to the third state.

16. A system, as in claim 11, where the one of the subsequences in the sequence of commands moves one or more first set of slaves from the first state to the second state and then moves the slaves in the first state to the third state.

17. A method to generate a sequence of commands that are broadcasted to one or more slaves, the method comprising the steps for:

a. communicating one or more first commands that move zero or more of the slaves from a first state to a second state, the slaves moving from the first state to the second state satisfying a first primitive condition in each respective second command;

b. communicating zero or more second commands that move one or more of the slaves from the second state to the first state, the slaves moving from the first state to the second state satisfying a second primitive condition in each respective second command;

c. repeating steps a and b one or more times;

d. communicating a third command that moves the slaves in the second state into a third state.

18. A state machine slave comprising:

three or more states, being at least a first state, a second state, and a third state, the slave being in the first state;

means for storing one or more stored information values;

means for receiving one or more commands in a command sequence, each command specifying a “

transfer from state”

, a “

transfer to state”

, and a primitive condition; and

means for causing the slave to move to the second state being the “

transfer to state”

if the first state is the same as the “

transfer from state” and

one or more of the information values satisfies the primitive condition, the slave being moved to the third state by another command in the command sequence only if the slave is in the second state, and the slave, once moved into the third state, remaining in the third state.

19. A system comprising:

two or more slaves, the slaves comprising;

three or more states, being at least a first state, a second state, and a third state, the slave being in the first state;

means for storing one or more information values;

means for receiving one or more commands in a command sequence, each command specifying a “

transfer from state”

, a “

transfer to state”

, and primitive condition;

means for causing the slave to move to the second state being the “

transfer to state”

if the first state is the same as the “

transfer from state” and

one or more of the information values satisfies the primitive condition, the slave being capable of being moved to the third state by another command in the command sequence only if the slave is in the second state, and the slave, once moved into the third state, remaining in the third state; and

one or more means for communicating each command to all the slaves and determining the sequence of commands in order to select a sub-set of the slaves that satisfy a condition.