Self-programmable battery load/bias for memory expansion module

• US 6,459,173 B1
• Filed: 10/30/2000
• Issued: 10/01/2002
• Est. Priority Date: 10/30/2000
• Status: Expired due to Term

• Current Assignee: Rockwell Technologies, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Gunsaulus, Richard Scott, Floro, William E.
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): DeBeradinis, Robert L
• Application Number:
  US09/699,802
• Time in Patent Office: 701 Days
• Field of Search: 307/66, 307/64, 307/85, 307/23, 307/18
• US Class Current: 307/66
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

A system and method is provided for selecting a test load and/or bias resistor utilized in an expandable load system employing a backup power source. The test load and/or bias resistor is selected based on the actual load present in the expandable system. The backup power source is periodically tested during normal operation of the expandable load system utilizing the test load. A test load is provided that is sized for the actual load of a local load under worse case conditions. If an expansion load is connected to the local load the test load is adjusted, so that the test load is based on the actual load of the local load and the expansion load. Additionally, a bias resistance can be provided for driving a switch that allows power to be provided to the local load during power loss mode. If an expansion load is connected to the local load, the bias resistance is adjusted to correspond to a bias resistance necessary to provide the current for the actual load of the local load and the expansion load.

Claims

1. An expandable load system employing a backup power source, the system comprising:

a test load component coupled to the backup power source, the test load component being operable to provide a test load based on an actual load of the system in a worse case condition for periodic testing of the backup power source during normal operation;

a switch component coupled to the backup power source, the switch component having a first state coupling the backup power source to the local load during a power loss mode and a second state decoupling the backup power source to the local load during normal operation; and

a bias resistance component coupled to the switch component, the bias resistance component being operable to provide a bias resistance necessary to provide a current through the switch component from the backup power source based on the actual load of the system in a worse case condition in the power loss mode.

2. The system of claim 1, the actual load comprising a local load and an optional expansion load coupled to the local load.

3. The system of claim 1, the test load component comprising a first test load resistor sized to provide adequate determination of the backup power source to provide current to the actual load in a worse case condition.

4. The system of claim 3, the test load component further comprising a second test load resistor residing on an optional expansion load, the second test load resistor being coupleable to be in parallel with the first test load to provide a test load sized to provide adequate determination of the backup power source to provide current to the local load and the optional expansion load in a worse case condition.

5. The system of claim 1, the bias resistance component comprising a first bias resistor sized to provide a bias resistance adequate for providing a current through the switch component from the backup power source to a local load for a worse case condition.

6. The system of claim 5, the bias resistance component further comprising a second bias resistor residing on an optional expansion load, the second bias resistor being coupleable to be in parallel with the first bias resistor to provide a bias resistance adequate for providing a current through the switch component from the backup power source for the local load and an optional expansion load in a worse case condition.

7. The system of claim 1, the switch component being a PNP transistor.

8. The system of claim 1, the test load component being further operable to provide a low power signal if the voltage of the backup power source falls below a predetermined level during test loading.

9. The system of claim 1, the backup power source being a rechargeable battery.

10. The system of claim 1, further comprising an optional expansion load coupled to the local load wherein the test load component is selectable to provide a test load adequate for determining the ability of the backup power source to provide current to the local load and the expansion load in a worse case condition.

11. The system of claim 10, further comprising a logic component operable to request and receive an optional expansion load ID and set the test load component based on the local load and the optional expansion load ID.

12. The system of claim 1, further comprising an optional expansion load coupled to a local load wherein the bias resistance component is selectable to provide a bias resistance adequate to provide the current necessary through the switch component from the backup power source to the local load and the expansion load in a worse case condition.

13. The system of claim 12, further comprising a logic component operable to request and receive an optional expansion load ID and set the bias resistance component based on the local load and the optional expansion load ID.

14. A method for selecting a test load for an expandable load system employing a backup power source and for selecting a bias resistance for driving a switch coupling the backup power source to an actual load, the method comprising the steps of:

determining an actual load present;

setting a test load based on the actual load present; and

setting a bias resistance according to the actual load present.

15. The method of claim 14, the actual load present comprising a local load and an expansion load.

16. The method of claim 14, the local load comprising a local memory and the expansion load comprising an expansion memory.

17. The method of claim 14, further comprising a step of reading an optional load ID prior to the step of determining the actual load present.

18. The method of claim 14, further comprising the step of determining if a change in load has occurred and repeating the step determining of the actual load present if a change in load has occurred.

19. A system having a local memory and a backup battery wherein the system is adapted to receive optional expansion memory, the system comprising:

a main module comprising a test load resistor coupled to a backup battery, the test load resistor being operable to provide a test load adequate for determining the ability of the backup battery to provide current to the actual load in a worse case condition for periodic testing of the backup battery during normal operation.

20. The system of claim 19, further comprising a second test load resistor residing on an optional expansion memory module coupleable to the main module, the second test load resistor being coupleable to be in parallel with the first test load resistor to provide a test load adequate for determining the ability of the backup battery to provide current to the local memory and an optional expansion memory in a worse case condition.

21. The system of claim 19, further comprising a PNP transistor switch coupled to the backup battery, the PNP transistor switch having an on state coupling the backup battery to the local memory during a power loss mode and an off state decoupling the backup battery to the local memory during normal operation.

22. The system of claim 21, further comprising a bias resistor coupled to the PNP transistor switch, the bias resistor being sized to provide a bias resistance adequate for providing a current through the PNP transistor switch from the backup power source for the actual load for the local memory of the system in a worse case condition in the power loss mode.

23. The system of claim 22, further comprising a second bias resistor residing on an optional expansion memory module coupleable to the main module, the second bias resistor being coupleable to be in parallel with the first bias resistor to provide a bias resistance adequate for providing a current through the PNP transistor switch from the backup battery for the local memory and an optional expansion memory in a worse case condition.

24. The system of claim 19, the backup battery being a non-rechargeable battery.

25. The system of claim 19, the main module being an industrial control module.

26. A system for selecting a test load for an expandable load system employing a backup power source and for selecting a bias resistance for driving a switch coupling the backup power source to an actual load, the system comprising:

means for determining an actual load present;

means for setting a test load based on the actual load present; and

means for setting a bias resistance according to an actual load present.

27. The system of claim 26, the actual load present comprising a local load and an expansion load.

28. The system of claim 26, the local load comprising a local memory and the expansion load comprising an expansion memory.