Apparatus and methods for communicating with a downhole tool

1. An apparatus for communicating with a downhole tool to alter the tool's power status, the apparatus comprising:

a sensor body comprising at least two electrodes electrically insulated from the sensor body and one another; and

an external control device having contact areas configured to physically engage and establish electrical contact with the two electrodes, wherein the external control device is configured to have a predetermined electrical status; and

sensor body electronics comprising:

detection circuitry connected to the two electrodes and configured to monitor an electrical status across the external control device; and

power management circuitry configured to generate a command for controlling a power status of the downhole tool,

wherein the detection circuitry periodically monitors the electrical status across the external control device in a programmed pattern at regular periodic time intervals, and upon detecting a change from the predetermined electrical status of the external control device, the detection circuitry communicates a command to the power management circuitry to alter a power status of the downhole tool.

2. The apparatus of claim 1 , wherein the external control device is configured as a metal wire.

3. The apparatus of claim 1 , wherein the two electrodes are electrically insulated by non-conducting material comprising one of ceramic, fiberglass, epoxy or PEEK.

4. The apparatus of claim 1 , wherein at least one of the electrodes comprises a coil configured to detect a time-varying electromagnetic field.

5. The apparatus of claim 1 , wherein the detection and power management circuitry are part of a sensor electronics package embedded in the sensor body.

6. The apparatus of claim 1 , wherein the electrical status comprises an electrical resistance level across the two electrodes.

7. The apparatus of claim 1 , wherein the electrical status comprises an electrical capacitance level across the two electrodes.

8. The apparatus of claim 1 , wherein the electrical status comprises an electrical inductance level across the two electrodes.

9. The apparatus of claim 1 , wherein the electrical status comprises an electrical voltage level across the two electrodes.

10. The apparatus of claim 1 , wherein two segments of the sensor body comprise the two electrodes.

11. The downhole tool of claim 1 , wherein the electrical status is selected from the group consisting of electrical resistance, capacitance, inductance, and voltage, across the two electrodes.

12. The apparatus of claim 1 , wherein the external control device is configured to be clamped to the sensor body.

13. The apparatus of claim 12 , further comprising a locking bolt configured to secure the external control device to the sensor body.

14. A method of communicating with a downhole tool to alter the tool's power status using an apparatus comprising a sensor body having at least two electrodes electrically insulated from one another and an external control device configured to engage the two electrodes, the method comprising:

periodically monitoring in a preprogrammed pattern at regular periodic time intervals, with detection circuitry, through the external control device physically engaged with the two electrodes, a predetermined electrical status across the two electrodes;

detecting a change in the electrical status from the predetermined electrical status of the external control device; and

transmitting a command to power management circuitry to alter a power status of the downhole tool.

15. The method of claim 14 , further comprising monitoring an electrical resistance level across the two electrodes.

16. The method of claim 14 , further comprising monitoring an electrical capacitance level across the two electrodes.

17. The method of claim 14 , further comprising monitoring an electrical inductance level across the two electrodes.

18. The method of claim 14 , further comprising monitoring an electrical voltage level across the two electrodes.

19. The method of claim 14 , further comprising detecting the electrical status through the external control device at regular periodic intervals.

20. A downhole tool, comprising:

an apparatus for communicating with the downhole tool to alter a power status of the downhole tool, the apparatus comprising:

a sensor body comprising at least two electrodes electrically insulated from one another;

an external control device configured to physically engage and establish electrical contact with the two electrodes, wherein the external control device is configured to have a predetermined electrical status;

detection circuitry embedded in the apparatus configured to monitor an electrical status across the two electrodes, through the external control device; and

power management circuitry configured to alter a power status of the downhole tool upon receiving a command from the detection circuitry,

wherein the detection circuitry periodically monitors the electrical status across the external control device in a programmed pattern at regular periodic time intervals, and upon the detection circuitry detecting a change in the predetermined electrical status from the predetermined electrical status, the power management circuitry is commanded by the detection circuitry to alter a power status of the downhole tool.