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.

Description:
TECHNICAL FIELD 
   This invention relates generally to a blasting system and is particularly concerned with a method of and system for controlling the operation of a blasting network. 
   BACKGROUND OF THE INVENTION 
   For safety reasons a blast controlling system used for remotely controlling a blasting network has traditionally been isolated from other networks at a blasting site eg. at a mine. The data on the blasting system can however be used to monitor productivity, implement stock control and improve mining methods by making blast information available to those who need such information. It is also possible to schedule and initiate blasts from a central control facility through a suitable blast controlling system. 
   Another possibility which arises particularly due to the fact that computers are being used as top level system controllers for distributed networks of blasters is to make use of a computer network using Internet or Intranet capabilities. There are however inherent risks associated with Internet connections. Chief of these is the risk that a hacker or unauthorised user may penetrate the system and deliberately or inadvertently generate an unsafe or dangerous command which can arm and fire the blasting system. This type of action can have catastrophic results. 
   SUMMARY OF THE INVENTION 
   The invention provides a method of controlling a blasting network which includes the steps of designating at least one unsafe message, placing a communication link between a control unit and the network in a control mode in which the communication link is monitored for the unsafe message, in said control mode preventing the unsafe message, when detected, from reaching the blasting network, and placing the communication link in an operational mode in which any previously designated unsafe message is allowed to reach the blasting network, and wherein in both the control mode and the operational mode any message which has not been designated as unsafe is permitted to be transmitted via the communication link. 
   The invention also provides a system for controlling a blasting network which includes a control unit and a communication link for the network, the communication link being capable of being placed in a control mode and in an operational mode, and a monitoring device for monitoring the communication link for at least one previously designated unsafe message, wherein the communication link in its control mode prevents any detected unsafe message from being transmitted to the blasting network and in its operational mode permits any previously designated unsafe message to be transmitted to the blasting network, and wherein in both its control mode and its operational mode the communication link permits any message which has not designated as unsafe to be transmitted via the communication link. 
   Further according to the present invention there is provided a blasting system including a control system as described in the immediately preceding paragraph connected to a blasting network. 
   “Unsafe message”, as used herein, is used to designate a message or command which, if received by the blasting network, could result in unwanted or adverse conditions or consequences. For example arm and fire commands, if received by the blasting network at an unwanted time, could cause a blast to be initiated in the presence of personnel and thereby result in death or injury. 
   Preferably therefore the method of the invention includes the step of designating at least two unsafe messages of which two are respectively equated with arm and fire commands. 
   In the control mode of the communication link, the or each unsafe message may be prevented from reaching the blasting network simply by ignoring the message and not allowing its onward transmission. Alternatively the or each unsafe message may be scrambled so that it is no longer in an unsafe form. 
   In the operational mode of the communication link, in which unsafe messages are allowed to be transmitted to the blasting network, any previously scrambled unsafe message may be detected and unscrambled prior to transmitting the unscrambled unsafe message to the blasting network. 
   The control unit may be capable of generating legal unsafe messages, for example legitimate arm and fire commands, which are transmitted via the communication link in its operational mode. However, unsafe messages may be categorised as legal or illegal. The latter group of messages includes those which are illegally generated, for example those messages which arise from any source other than the control unit connected to the communication link. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of a control method and system according to the invention will now be described by way of example only with reference to the accompanying drawings in which: 
       FIG. 1  is a block diagram of an electronic blasting system including one embodiment of a control system according to the invention; 
       FIG. 2  is a block diagram of a communication fire wall for use in the control system of  FIG. 1 ; 
       FIG. 3  is a logical flowchart of the operation of a filter, used in the control system of  FIG. 1 , according to a first form of the control system; and 
       FIG. 4  is a flowchart similar to that shown in  FIG. 3  for a variation of the control system. 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
   When a blasting system is connected to an Intranet or Internet facility, access is provided to information stored in a data base associated with the blasting system. This information is useful inter alia to managers, personnel involved in stores and production, seismic monitoring installations, logistical control units, etc. 
   A perceived risk with a connection of the aforementioned kind is that unauthorised users may hack through the network security to tamper with the blasting system which is a safety critical system. An unanticipated system fault may result in the safety of the system being compromised and this may lead to the blasting system being fired prematurely which can cause injury or fatalities. 
   Modern networks provide high levels of user security but due to the complexities of such systems it is not always possible to carry out a complete exhaustive safety analysis of the control software, operating systems and associated fire walls. 
     FIG. 1  of the accompanying drawings illustrates in block diagram form a system which allows an Internet or Intranet connection to be made to a blasting network with improved safety. 
   The system includes an Internet or Intranet facility or connection arrangement  10 , a blasting controller or control computer  12  which is used to control and activate blasts remotely, a communication fire wall  14 , a blasting network  16 , and a variety of interrogating terminals  18 . 
   The blasting controller  12  is used in a known manner and includes a standard device employed to control the network  16  and to activate the initiation thereof, remotely. These aspects are known in the art and hence are not further described herein. Similarly the blasting network  16  consists of an assembly of detonators and communication devices installed in a known manner at a blasting site, making use of known technology. 
   The communication fire wall includes a locking device  19  for placing a communication link  20 , which may be an electrical conductor, to the blasting network in a control mode, or in an operational mode, according to requirement. As used herein the expression “locking device” includes any switchable component or mechanism which allows the fire wall to be made operational, or to be rendered inoperational, according to requirement. The locking device may be operated using a key, by means of an electronic keypad requiring a password, or it may be a remotely activated switch on a private connection. Thus, in a general sense, the locking device may be mechanically or electronically operated. 
   The remote terminals  18  may vary according to requirement. The terminals may for example provide access, via an Internet connection, to the blasting network for managers  18 A, stock controllers  18 B, or a seismic monitoring unit  18 C. These examples are merely illustrative and are not limiting. 
     FIG. 2  illustrates further detail of the communication fire wall  14 . The communication firewall includes communication interfaces  22  and  24  which allow communication to take place with the communication link  20 , an electronic filter  26  and, in this example, a locking device  19  which consists of a mechanical or electronic switch  28  which is activated by means of a mechanical or electronic key  30 . 
   The operation of the electronic filter  26  is described hereinafter with reference to  FIG. 3  and a variation of such operation is described with reference to  FIG. 4 . 
   As indicated, by connecting the blasting system  16  to the Internet  10  a potential safety risk is introduced due to the possibility being created that hackers can penetrate the system. This risk is eliminated, or at least substantially reduced, by making use of the communication fire wall  14  to selectively filter out unsafe or dangerous commands like “arm”, which results in the blasting network being armed, and “fire” which causes the blasting network to be initiated. 
   It is to be noted that the communication medium and protocols used to communicate between the blast controlling system and the blasting network may be of any appropriate type capable of achieving reliable communication. 
   The communication interfaces allow the communication to interface with the electronic components incorporated in the filter  26 . These electronic components may include a micro controller, programmable logic devices or discrete components. The choice of the electronic components is determined inter alia by the complexity of the communication protocol which is used. 
   Referring to  FIG. 3 , data on the link  20  (block  32 ) is received from the communication interface  22  and is input to the filter  26 . The filter waits for communication ( 34 ) and reads each message on the line ( 36 ). If a message is unsuccessfully read then the system returns to the mode at which it awaits communication. 
   Once a message is successfully read (block  38 ) a test is carried out to see if the filter  26  has been deactivated (step  40 ) to place the communication link  20  in its operational mode. As noted, the filter is deactivated by means of the mechanical key  30 . When the filter is deactivated the communication link  20  is capable of transmitting designated unsafe or dangerous messages, such as arm and fire commands, which have been legally generated by means of the blasting computer  12 , to the blasting network  16 . Thus if the filter has been deactivated (step  42 ) any message received, regardless of its origin, is collected (block  44 ) and transmitted via the communication interface  24  as output data ( 46 ). The system then reverts to its waiting mode at which further messages are awaited. 
   On the other hand if the filter  26  is activated so that the communication link is in its control mode, any message received is tested to see whether it is safe or unsafe (step  48 ). Safe messages are collected and transmitted on the communication link (steps  44  and  46 ) to the communication interface  24 . If a designated unsafe message is detected, it is collected but simply ignored (step  50 ). The system then reverts to the mode at which it waits for further communication. 
   If an unsafe or dangerous message is detected with the filter  26  activated then an alarm signal, visual or audible, is generated. A count is also kept of the number of unsafe messages detected. 
   With the control steps shown in  FIG. 3  the logic is such that unsafe messages which are detected when the filter is activated are assumed to be illegally generated and are ignored. Other messages are transmitted to the required destination via the communication interface  24 . The system thus possesses the facility for allowing data associated with the blast network to be accessed from the remote points  18 . The data may be located at the blasting controller  12  or at the blasting network  16 . It is however not possible to transmit a designated unsafe message to the network  16  unless the communication link  20  has been placed in its operational mode, ie. unless the filter  26  has been deactivated. 
   In the logical sequence shown in  FIG. 4  many of the steps are similar or identical to corresponding steps in the sequence shown in  FIG. 3  and consequently bear the same reference numerals. The flowchart shown in  FIG. 4  is however intended for use with a blasting controller  12  which scrambles designated unsafe messages. Thus, legally generated arm and fire commands, produced by the controller  12 , may be transmitted to the blasting network  16  in a scrambled state when the filter  26  is activated, but these scrambled messages will be ignored since they will not be understood by the blasting network as arm and fire commands. 
   In the step  40  a test is carried out to see if the filter  26  is deactivated (ie the communication link  20  is in its operational mode) or activated (ie the communication link  20  is in its control mode). In the latter case a test is then carried out on the received message to see whether it contains a designated unsafe or dangerous command such as “fire” or “arm” (step  52 ). If the message is unsafe then, in step  54 , the command is scrambled whereafter the scrambled command is collected and transmitted (steps  44  and  46 ). By scrambling an unsafe message, the unsafe message is converted into a safe message. 
   On the other hand if the received message is safe then no scrambling takes place and the message is transmitted in an unscrambled form to its destination. 
   If the filter has not been activated, so that the communication link is in its operational mode, a test is carried out in step  56  to determine whether the received message is a scrambled unsafe message such as a scrambled fire or arm command. A scrambled message is unscrambled (step  58 ) and is then transmitted to its destination via the communication interface  24 . If the message is not a scrambled unsafe message then, in step  52 , a test is carried out to see if the message is an unsafe message in unscrambled form. If the test result is affirmative then it is assumed that the message has been illegally generated and, as before, the message is scrambled (step  54 ) before being transmitted. If the test result is negative then the message is transmitted in the received form to its destination via the communication interface  24 . 
   It follows that the locking device  19  is used to bypass the filter  26  when it is safe to blast. The bypass is achieved by hard wiring the communication around the filter or by the filter sensing the status of the switch and then, based on the status, filtering the dangerous commands out or unscrambling them. 
   If the filter has sufficient intelligence then it can send the arm and fire commands. It would therefore not be possible for an unauthorised user to initiate a blast. This could only be achieved by deactivating the fire wall via the mechanical or locking device  19 . 
   The control computer  12  may communicate directly with the filter  26 . If there is no response from the filter then the control computer will not attempt communication with the blasting network. The filter can thus act as a software dongle. If, as is the case with the  FIG. 4  embodiment, dangerous legal messages are scrambled then the filter must be activated for the system to operate. 
   It is to be noted that normal commands to query the blasting network and to determine the status of components at the blasting site are unaffected. Once the blast area is clear the mechanical or electrical key is used to disable the filtering action and unblock the commands. The arm and fire commands may now be sent through the filter via the blast network to the blasting equipment. The control computer will scramble the dangerous commands. The filter, when unblocked, will correct the scrambled commands. If the filter is deactivated the scrambled dangerous commands will be sent to the blasting network. The blasting network will disregard these commands. 
   In the  FIG. 4  embodiment, an illegally generated unsafe message, that is an unsafe message not generated by the blasting controller  12 , would have to have the same scrambled format as a legally generated scrambled unsafe message to initiate blasting once it has been unscrambled. 
   In the embodiments of the invention described with reference to  FIGS. 3 and 4 , the filter  26  is activated to place it in the safe or control mode in which unsafe messages can not be transmitted to the blasting network  16  and deactivated to place it in the unsafe or operational mode in which unsafe messages are transmitted. However, it is to be understood that the filter  26  may be one in which the safe or control mode is achieved by deactivating or otherwise switching the filter and the unsafe or operational mode is achieved by activating or otherwise switching the filter. In other words, what is important in this respect is merely that the filter can be switched between control and operational modes. 
   Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within its spirit and scope.