Determining the order of devices in a downhole string

An apparatus comprising:

• a string of subs comprising:
• a controller sub, comprising:
• a first end;
• a second end;
• a controller;
• a first controller bus coupled to the controller of the controller sub, the first controller bus exiting at the first end of the controller sub;
• and
• a second controller bus coupled to the controller of the controller sub, the second controller bus being separate from the first controller bus, the second controller bus exiting at the second end of the controller sub;
• a first measuring sub;
• and
• a second measuring sub;
• a computer, said computer programmed to perform a process, wherein the process comprising:
• discover that the first measuring sub is connected to the first controller bus;
• discover that the second measuring sub is connected to the first controller bus;
• determine that the first measuring sub is physically closer to the controller sub than the second measuring sub;
• and
• use the determination that the first measuring sub is physically closer to the controller sub than the second measuring sub in controlling an operation of the string of subs,
• wherein said to determine that the first measuring sub is physically closer to the controller sub than the second measuring sub comprises:
• imposing a voltage on the first controller bus by the controller sub while leaving the first controller bus in an open loop configuration,
• measuring a first voltage across the first controller bus at the first measuring sub,
• measuring a second voltage across the first controller bus at the second measuring sub;
• and
• determining that the first voltage is greater than the second voltage by directly comparing the first voltage to the second voltage.

An apparatus comprising:

• a string of subs comprising:
• a controller sub, comprising:
• a first end;
• a second end;
• a controller;
• a first controller bus coupled to the controller of the controller sub, the first controller bus exiting at the first end of the controller sub;
• and
• a second controller bus coupled to the controller of the controller sub, the second controller bus being separate from the first controller bus, the second controller bus exiting at the second end of the controller sub;
• a first measuring sub;
• a second measuring sub;
• a first reamer sub comprising a first weight-on-bit measuring device;
• and
• a second reamer sub comprising a second weight-on-bit measuring device;
• the controller of the controller sub programmed to perform a process, wherein the process comprising to:
• discover that the first reamer sub is connected to the first controller bus;
• discover that the second reamer sub is connected to the first controller bus;
• determine that the first reamer sub is physically closer to the controller sub than the second reamer sub;
• determine the first measuring sub is physically closer to the controller sub than the second measuring sub;
• and
• use the determination that the first measuring sub is physically closer to the controller sub than the second measuring sub in controlling drilling operations using the string of subs,
• wherein said to determine the first measuring sub is physically closer to the controller sub than the second measuring sub comprising:
• imposing a voltage on the first controller bus by the controller sub while leaving the first controller bus in an open loop configuration,
• measuring a first voltage across the first controller bus at the first measuring sub, and
• measuring a second voltage across the first controller bus at the second measuring sub;
• determining that the first voltage is greater than the second voltage by directly comparing the first voltage to the second voltage.

A computer program, stored in a non-transitory computer-readable tangible medium, the computer program comprising executable instructions that cause a computer to:

• discover that a first measuring sub, which is part of a string of subs including a controller sub and a second measuring sub, is connected to a first controller bus originating in the controller sub;
• discover that the second measuring sub is connected to the first controller bus;
• determine that the first measuring sub is physically closer to the controller sub than the second measuring sub;
• and
• use the determination that the first measuring sub is physically closer to the controller sub than the second measuring sub in controlling an operation of the string of subs,
• wherein said to determine that the first measuring sub is physically closer to the controller sub than the second measuring sub comprises:
• imposing a voltage on the first controller bus by the controller sub while leaving the first controller bus in an open loop configuration,
• measuring a first voltage across the first controller bus at the first measuring sub,
• measuring a second voltage across the first controller bus at the second measuring sub, and
• determining that the first voltage is greater than the second voltage by directly comparing the first voltage to the second voltage.