Abstract: A method and system for controlling a blasting network (16) for use where spurious command signals may be passed through a blasting controller (12) to the blasting network, for example when the controller is connected to the Internet or Intranet (10). The system includes a firewall (14) whereby the communication link (20) between the controller and the blasting network can be placed in a control mode by a switch (19). In the control mode, any previously designated unsafe message such as a fire command is prevented from reaching the blasting network by, for example, disregarding the unsafe message or scrambling it so that it is no longer unsafe. In an operational mode of the communication link, any scrambled unsafe message may be unscrambled and any unsafe message may be transmitted to the blasting network.

Abstract: An electronic explosives initiating device which includes a firing element which has a designed no-fire voltage and an operating circuit which operates at any voltage in a range of voltages which straddles the designed no-fire voltage.