A control device having a dedicated hierarchy level configured to obtain DC current from a power source on the control network , the control device is characterized in that the control device comprises: - a communication subsystem configured to - send a first query (QRY) over the control network to the power source regarding an amount of available current of the power source ; - receive a reply (RLY) over the control network from the power source about the amount of available current; - a controller configured to determine if the amount of available current of the power source is sufficient as compared to a required supply current of the control device ; and wherein the communication subsystem is further configured to: - send a command (CMD) over the control network to a second control device having a dedicated hierarchy level lower than the control device , instructing the second control device to send a release request to the power source to release supply current allocated to the second control device , when the amount of available current of the power source is determined insufficient; and - send a current request (C_RST) over the control network to the power source for the required supply current, when the amount of available current of the power source is determined sufficient or after confirming the command is executed by the second control device . the control device comprises: - a communication subsystem configured to - send a first query (QRY) over the control network to the power source regarding an amount of available current of the power source ; - receive a reply (RLY) over the control network from the power source about the amount of available current; - a controller configured to determine if the amount of available current of the power source is sufficient as compared to a required supply current of the control device ; and - a communication subsystem configured to - send a first query (QRY) over the control network to the power source regarding an amount of available current of the power source ; - receive a reply (RLY) over the control network from the power source about the amount of available current; - a controller configured to determine if the amount of available current of the power source is sufficient as compared to a required supply current of the control device ; and wherein the communication subsystem is further configured to: - send a command (CMD) over the control network to a second control device having a dedicated hierarchy level lower than the control device , instructing the second control device to send a release request to the power source to release supply current allocated to the second control device , when the amount of available current of the power source is determined insufficient; and - send a current request (C_RST) over the control network to the power source for the required supply current, when the amount of available current of the power source is determined sufficient or after confirming the command is executed by the second control device . - send a command (CMD) over the control network to a second control device having a dedicated hierarchy level lower than the control device , instructing the second control device to send a release request to the power source to release supply current allocated to the second control device , when the amount of available current of the power source is determined insufficient; and - send a current request (C_RST) over the control network to the power source for the required supply current, when the amount of available current of the power source is determined sufficient or after confirming the command is executed by the second control device . <EOS>