Controlling devices using cascaded control units
Power supplies, supplied with an input voltage to produce output voltages, are controlled in a desired sequence, and their output voltages are monitored, by respective state machines of two or more control units which are coupled in cascade by a bidirectional signal path on which commands and acknowledgements are coupled serially in frames. Within each control unit, each state machine communicates with all of the other state machines, so that the power supplies controlled by a single control unit can include divergent and convergent as well as linear sequence paths. The sequence is linear between adjacent control units, with logical combinations of received and locally-produced commands and acknowledgements. An input state machine in the first control unit in the cascade monitors the input voltage to initiate a power-up sequence.
1. A method of controlling a plurality of controlled devices in a predetermined sequence, comprising the steps of:
providing a plurality of control units each comprising a plurality of state machines each for controlling a respective controlled device;
allocating the plurality of controlled devices to respective state machines in said plurality of control units whereby the control units are cascaded in accordance with the predetermined sequence, with a single linear path of the predetermined sequence between adjacent cascaded control units;
within each of the control units, coupling signals of each state machine to each other state machine for controlling the respective controlled devices, controlled by said state machines, in accordance with the predetermined sequence; and
between adjacent ones of the cascaded control units, coupling signals relating to the state machines of the control units in both directions between the cascaded units for control of the controlled devices in accordance with the predetermined sequence.
2. A method as claimed in claim 1 wherein the signals relating to the state machines of the control units are coupled serially in signal frames between the adjacent cascaded units.
3. A method as claimed in claim 1 and including the step of, in at least one control unit, logically combining signals relating to the state machines of the control units received from a preceding control unit in a respective signal direction with signals relating to the state machines of said one control unit to produce the signals relating to the state machines of the control units for a subsequent control unit in the respective signal direction.
4. A method as claimed in claim 1 wherein the controlled devices comprise power supplies.
5. A method of controlling a plurality of power supplies, comprising the steps of:
providing a plurality of power supply controller units (PSCUs) in cascade, each PSCU comprising an input state machine for monitoring an input voltage for the power supplies and a plurality of further state machines each for enabling and monitoring an output of a respective power supply;
in a first PSCU in the cascade, determining for each of said further state machines a dependence upon the input voltage or the output of a power supply as monitored by at least one other state machine of this first PSCU, for enabling the respective power supply;
in each subsequent PSCU in the cascade, determining for one of the further state machines of this subsequent PSCU a dependence upon the output of a power supply as monitored by a state machine of the respective preceding PSCU, and determining for each other of the further state machines of this subsequent PSCU a dependence upon the output of a power supply as monitored by at least one other state machine of this subsequent PSCU, for enabling the respective power supply; and
coupling signals relating to the state machines of the PSCUs in both directions between adjacent PSCUs in the cascade;
whereby the power supplies are enabled in a predetermined sequence in dependence upon the input voltage.
6. A method as claimed in claim 5 wherein the signals coupled between adjacent PSCUs comprise commands for enabling or disabling the controlled power supplies and acknowledgements of said commands.
7. A method as claimed in claim 5 wherein the signals relating to the state machines of the PSCUs are coupled between the adjacent PSCUs in the cascade serially in signal frames.
8. A method as claimed in claim 7 wherein the signals coupled between the adjacent PSCUs comprise commands for enabling or disabling the controlled power supplies and acknowledgements of said commands.
9. A method as claimed in claim 5 wherein there are at least three PSCUs, the method including the step of, in at least one PSCU, logically combining signals relating to the state machines of the PSCUs received from a preceding PSCU in a respective signal direction with signals relating to the state machines of said one PSCU to produce the signals relating to the state machines of the PSCUs for a subsequent PSCU in the respective signal direction.
10. A method as claimed in claim 5 wherein a dependence upon the input voltage is determined for at least two of said further state machines in the first PSCU in the cascade for enabling the respective power supplies.
11. A method as claimed in claim 5 wherein, in at least one of the PSCUs, a dependence upon the output of the same power supply, as monitored by at least one other state machine, is determined for each of at least two of said further state machines of the PSCU.
12. A method as claimed in claim 5 wherein, in at least one of the PSCUs, a dependence upon the outputs of a plurality of power supplies, as monitored by a corresponding plurality of other state machines, is determined for at least one of said further state machines of the PSCU.
13. A power supply control arrangement comprising:
a plurality of power supply controller units (PSCUs) each comprising an input state machine for monitoring an input voltage for a plurality of controlled power supplies and a plurality of further state machines each for enabling and monitoring an output of a respective power supply, the PSCUs being coupled in cascade for signal coupling therebetween, and the state machines being arranged, for carrying out the method of claim 5 ; and
a plurality of power supplies arranged to receive said input voltage and controlled by respective ones of said further state machines.
14. A power supply control arrangement as claimed in claim 13 wherein the PSCUs comprise programmable devices identical to one another.
15. A power supply control arrangement as claimed in claim 14 wherein each PSCU includes a non-volatile memory for storing information relating to the predetermined sequence for the power supplies controlled by the PSCU.