Devices, systems, and methods for initializing a PLC module

1. A system comprising:

a first module of a first chain of modules, each adjacent pair of said first chain of modules communicatively coupled in series to a programmable logic controller (PLC), said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B/10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said first chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.

2. The system of claim 1 , further comprising:

a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series to said PLC.

3. The system of claim 1 , further comprising:

a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series to said PLC, wherein said second chain of modules comprise communication modules.

4. The system of claim 1 , further comprising:

said PLC.

5. The system of claim 1 , wherein said first switch is adapted to close subsequent to said assignment of said module address to said first module.

6. The system of claim 1 , wherein said second switch is dynamically controlled to allow transmission from the first module toward the PLC when the first module has information to send, or selects the second repeater to allow any message presented from the direction of the second module to be repeated toward the PLC.

7. The system of claim 1 , wherein first chain of modules comprises only Input/Output modules.

8. The system of claim 1 , wherein said first module is implemented via an ASIC controlled by machine instructions.

9. The system of claim 1 , wherein said PLC is implemented via an ASIC controlled by machine instructions.

10. The system of claim 1 , wherein said first module is implemented via software.

11. The system of claim 1 , wherein said first module is implemented via firmware.

12. The system of claim 1 , wherein said PLC is implemented via firmware.

13. The system of claim 1 , wherein said first module is implemented via an FPGA controlled by machine instructions.

14. The system of claim 1 , wherein said PLC is implemented via an FPGA controlled by machine instructions.

15. A method comprising:

transmitting a message from a programmable logic controller (PLC) that is communicatively coupled to a first module of a first chain of modules, each adjacent pair of said first chain of modules communicatively coupled in series, each of said first chain of modules Input/Output modules adapted to communicate with said PLC in hard real-time, said PLC communicatively coupled to a second chain of modules, each adjacent pair of said second chain of modules communicatively coupled in series, each of said second chain of modules a communications module, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B/10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said first chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module, each of said 8B/10B encoded frames comprising message type field of a size that corresponds to eight bits, a value stored in said message type field indicative of content of a data field of said frame, said message type field following a first ordered sequence of fields comprised by said frame, said first ordered sequence of fields, a preamble field, a start-of-frame field, a destination address field of a size that corresponds to eight bits, a length field, and a source address field of a size that corresponds to eight bits, said message type field followed by a second ordered sequence of fields comprised by said frame, said second ordered sequence comprising a data field, a cyclic redundancy check field of a size that corresponds to 32 bits, and an end of frame field.

16. A machine-readable medium comprising machine instructions for activities comprising:

communicatively coupling a programmable logic controller (PLC) to a first module of a chain of modules, each adjacent pair of said chain of modules communicatively coupled in series, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B/10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.

17. A system comprising:

a circuit adapted to communicatively couple a programmable logic controller (PLC) to a first module of a chain of modules, each adjacent pair of said chain of modules communicatively coupled in series, said first module comprising a transmitting circuit, a receiving circuit, and repeater circuits, said first module adapted to communicate with said PLC via 8B/10B encoded frames, said first module comprising a first repeater which repeats transmissions from the direction of the PLC to a second module of said chain of modules, said first repeater comprising a first switch, said first switch adapted to default to an open position prior to an assignment of a module address to said first module by said PLC, said first switch adapted to remain in said open position until said module address is assigned to said first module, said first module further comprising a second repeater which repeats transmissions from the direction of the second module to the direction of the PLC, said second repeater comprising a second switch selecting whether communication toward the PLC is from the first module transmission circuit or repeated from the second module.