1. PC – RCX Management Application

2. FEATURES This is an application similar to SNMP, for managing the RCX brick from a PC. PC queries/sets the status of the various objects on the brick. The RCX brick can report any failures to the PC.

3. COMPONENTS Agent – RCX. The device which is managed. MIB – Management Information Base This is a hierarchical arrangement of the various objects on the agent that can be monitored. NMS – Network Management Station (PC) This refers to the manager which sends the queries/set messages to the agent.

4. COMMUNICATION Protocol for communication is based on LLC. 2 layers involved –LLC –LLC Reliable Handler RCXPort() IR forms the physical layer for communication.

5. ARCHITECTURE NMSAgent Request Reply Trap Trap Reply MIB Trap Ack

6. MESSAGES Request Message –Sent from NMS to Agent –Get / Set Messages –Each request message is sent as a series of bytes –Message Size, Id Size, Identifier, Type of Message, Tag Value, Extra Data

7. MESSAGES(contd..) Reply Message - Get Message – Value written as a short integer in two bytes. - Set Message – No reply sent back.

8. MESSAGES ( contd..) Trap Message –Sent in emergency situations –Used to notify the NMS about its situation so that some recovery action could be taken up by the NMS. –Unique Identifier

9. MESSAGES ( contd..) Trap Reply Message - Sent from the NMS to the Agent. - Specifies the recovery action to be taken. Trap Ack Message –Sent back from the agent to the NMS once the agent has recovered. –Helps notify the NMS to start its normal querying.

10. MIB Managed objects comprise the MIB. A managed object in the RCX is a component whose status can be queried or set. Egs., of managed objects in the RCX –Sensor, Motor,Memory –Types of Sensors – Touch, Light –Instances of Sensors are S1, S2, S3 –Instances of Motors are A, B, C

11. MIB ORGANISATION RCX Sensor MotorMemory TouchLightTemperature S1S2S3 S1S2S3S1S2S3 1 0 12 0 1 2 012 012 0 12 Eg: Identifier for touch sensor S1: 1.0.0.0.

12. PARAMETERS ASSOCIATED WITH THE OBJECTS Memory –Retrieves the amount of free memory available Status of the motors –flt() –forward() –backward() –reversedirection() –setPower() –Stop() Sensors –A sensor can be activated or passivated

13. TRAP SITUATIONS A trap message could be sent in the following situations –When voltage is getting low –When the brick is low on memory

14. TRAP MESSAGES When an emergency situation arises, a trap message is sent to the NMS. The agent suspends all other activities of receiving queries from the NMS. When the NMS receives a trap it suspends its other activities and begins to process the trap message. A trap reply message will then be sent to the agent, depending on the type of trap request. On receiving the reply message the agent sends back a trap ack message.

15. FORMAL VERIFICATION UPPAAL will be used for verification Properties to be verified –Deadlock free