Abstract:
A blasting system with automated detonator logging eliminates on-the-field manual logging of each detonator. Detonators are connected in sequence in an auto-logging circuit, and the blast machine initiates a logging operation in which each detonator receives and confirms an assigned sequence number along with assigned delay data. Elimination of manual logging by individuals increases safety in the blast zone and facilitates the blasting operation. The operation is simplified, likelihood of human error is reduced, and the cost of a separate logger device is eliminated. An auto-logging protocol may be incorporated into the control module of the electronic detonator. Alternately, an auto-logging module may be connected externally to each detonator similar to the conventional surface plus down-the-hole delay systems. The inventive system may include an IDC connector that facilitates the serial connection of the detonators for the logging circuit while allowing parallel connections of the blast control circuit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application No. 62/294,567 entitled “Auto Logging Detonator,” filed Feb. 12, 2016, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates generally to electronic detonators and more particularly, but without limitation, to devices and methods for logging electronic detonators. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic illustration of an electronic detonator constructed in accordance with a first preferred embodiment of the present invention. In this embodiment, the auto-logging module is integrated into the detonator&#39;s control circuit. 
           [0004]      FIG. 2  is field connection diagram for a blast system comprising a plurality of electronic detonators each with an internal auto-logging module as illustrated in  FIG. 1 . 
           [0005]      FIG. 3  is a schematic illustration of an insulation displacement connector (“IDC”) customized for use in the blast system of the present invention. 
           [0006]      FIG. 4  is a schematic illustration of the IDC shown in  FIG. 3  with the blast wires, logging wires, blast lines, and logging line all connected. 
           [0007]      FIG. 5  shows a functioning block diagram showing the basic operation of a blasting system comprising a plurality of detonators each with an internal auto-logging module as illustrated in  FIG. 1 . 
           [0008]      FIG. 6  is a functional flow diagram illustrating the auto-logging logic carried out by the control module of auto-logging detonator show in  FIG. 1 . 
           [0009]      FIG. 7  is a functional flow diagram illustrating the auto-logging logic carried out by the blast machine in a blasting system employing the auto-logging detonator show in  FIG. 1 . 
           [0010]      FIG. 8  is a schematic illustration of an electronic detonator assembly constructed in accordance with a second preferred embodiment of the present invention. The electronic detonator assembly comprises a conventional electronic detonator electrically coupled to an external detonator logging unit. 
           [0011]      FIG. 8A  is an enlarged schematic illustration of the detonator logging unit  400  shown in  FIG. 8 . 
           [0012]      FIG. 9  is field connection diagram for a blast system comprising a plurality of electronic detonator and logging unit assemblies illustrated in  FIG. 8 . 
           [0013]      FIG. 10  shows a functioning block diagram showing the basic operation of a blasting system comprising a plurality of electronic detonator and logging unit assemblies as illustrated in  FIG. 9 . 
           [0014]      FIG. 11  is field connection diagram for a blast system comprising multiple rows of electronic detonator assemblies shown in  FIG. 8  and further comprising row-to-row row logging units. 
           [0015]      FIG. 12  shows a functioning block diagram showing the basic operation of a blasting system comprising a plurality of electronic detonator assemblies and row logging units as illustrated in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Electronic delay detonators are excellent initiation systems for controlled blasting especially in mining operations. Advantages of electronic detonators are precise timing resulting in reduced vibrations, improved protection from stray electrical currents and radio frequencies and, to an extent, reduction in misfires through precise circuit testing. Many types of electronic detonators are commercially available. Each manufacturer has different modes of operation for each model, which result in the similar functioning on the field. 
         [0017]    Irrespective of the various designs and modes of operations of the electronic detonators in the market today, certain procedures usually are carried out while executing a blast operation. Individual detonators are tested, and the boreholes are charged. All the detonators are logged, and the identity of each detonator and its position in the blast pattern is recorded. The blast machine uses this identity to communicate with individual detonators to test, transfer delay data, and to fire the detonators. 
         [0018]    The typical blast procedure also includes setting the delay time of each individual detonator according to the blast design. The delay time is transferred or programmed into the detonator either during the logging operation or by the blast machine during the blast procedure. 
         [0019]    All the detonators are connected to the main line, and the line testing is conducted to confirm that all detonators are detected in the circuit. This is done by addressing each individual detonator using its specific identity. 
         [0020]    In all cases, logging of the detonators on the field is mandatory to record the identity of each of the detonators with the blast hole. This is carried out either by physically connecting the detonator to the logging machine or by scanning the printed code on the detonator using an optical scanner. 
         [0021]    The logging is done on the charged holes while the operator stands on it. This is a safety hazard, especially when the logging is done using a physical connection of the detonator; this is because the detonator is powered, even though a safe voltage is being used for logging. In the case of the optical scanning system, a connected logging will be required if the label on the detonator is damaged. Regardless of the method of identification that is employed, all current systems require an operator to physically visit each blast hole and perform some operation in order to carry out the procedure. This process is time consuming and inconvenient and often requires additional personnel in the field. 
         [0022]    The present invention is directed to an electronic detonator with an auto-logging component that is either integrated in the circuitry of the detonator or in an external unit that is coupled to the detonator. The remote and automated logging process of this invention is carried out by communications between the blast machine and the detonators and eliminates the manual logging operation on the field. 
         [0023]    The present invention includes detonator-to-detonator or “D2D” communication in addition to the conventional blast machine-to-detonator communications. The D2D communication is carried out on a logging line or cable that interconnects the detonators in sequence or series all in a logging circuit with the blast machine. Whether the blast system utilizes electronic detonators with internal auto-logging circuits or an external auto-logging unit, the basic operation is similar. As used herein, “logging circuit” refers to the interconnected components that are involved in the auto-logging operation and includes the blast machine, the detonators, and the logging line by which the blast machine communicates with the detonators. In the context of the present invention, where external auto-logging modules are utilized, the detonator logging units and the row logging units form a part of the logging circuit. While the auto-logging circuit and the blast control circuit have common components, the communication lines may be separate and independent. 
         [0024]    The logging line that interconnects the detonators in series is in addition to the conventional two-wire blast lines, also called a bus line, that interconnect the detonators with the blast machine in a blast control circuit for execution of the blast program. As used herein, “blast control circuit” refers to the interconnected components of the blast operation and includes the blast machine, the detonators, and the data and communications lines by which the blast machine communicates with the detonators. In the context of the present invention, where external auto-logging modules are utilized, the auto-logging modules form a part of the blast control circuit. 
         [0025]    The present invention also provides a specially designed insulation displacement connector (“IDC”) for use when coupling the detonators to the three-wire bus line. The specialized IDC simplifies the serial or sequential connection of the electronic detonators in the logging circuit while also assuring secure connection to the blast lines as well. Essentially, this connector performs a serialized connection while appearing similar to connectors that perform a parallel connection. 
         [0026]    The present invention provides a blasting system in which automated remote electronic logging replaces the on-the-field logging of the detonators. This increases the safety of the on-field personnel also reduces the time required for the overall set up process. These and other features and advantages will become apparent from the following description with reference to the accompanying drawings. 
         [0027]    Turning now to the drawings in general and to  FIG. 1  in particular, there is shown therein an electronic detonator made in accordance with a first embodiment of the present invention and designated generally by the reference number  10 . The exemplary detonator  10  comprises a hollow tubular shell  12  with a blind or closed end  14  and an opposite open end  16 . An explosive charge is contained in the blind end  14  of the shell  12 . The explosive charge may include a base charge  20  and a primary explosive  22 . 
         [0028]    The detonator  10  includes a control module  26 . The control module  26  may be a microcontroller or programmable logic device and more preferably comprises an application-specific integrated circuit chip (ASIC). The control module  26  is programmed to communicate with the blast machine and carry out a plurality of operations including a firing operation in a known manner. In accordance with the present invention, the control module  26  further includes an auto-logging function or module that may be integrated into the control module. The control module  26  is operatively connected to an igniter of any suitable type to initiate the detonation of the explosive charge. In the exemplary detonator shown in  FIG. 1 , the igniter is a fuse head  28 . 
         [0029]    First and second leg wires  32   a ,  32   b  have internal ends  34   a ,  34   b  connected to the control module  26  and external ends  36   a ,  36   b  outside of the shell  12  for connection to the blast control circuit, described hereafter. Logging wires  38   a ,  38   b  having internal ends  40   a ,  40   b  operatively connected to the control module  26  and external ends  42   a ,  42   b  outside of the shell  12  for connecting the control module to the logging circuit also described below. An end plug or sealing plug  44  may be crimped in the open end  16  of the shell  12 . 
         [0030]    Referring now to  FIG. 2 , therein is shown an illustrative blast system  50  using a plurality of electronic detonators like the detonator  10  interconnected with a blast machine  52  by a three-wire bus line  54 . The bus line  54  comprises first and second blast lines  56   a  and  56   b  and a single logging line  60 . While four detonators  10   a ,  10   b ,  10   c , and  10   d  are shown, the blast system  50  may include a larger or smaller number of detonators. The detonators  10   a ,  10   b ,  10   c , and  10   d  are connected to the first and second blast lines  56   a ,  56   b  by the leg wires  32   a ,  32   b  to form the blast control circuit  62 . The logging wires  38   a ,  38   b  of the detonators  10   a ,  10   b ,  10   c , and  10   d  also are connected to the logging line  60  to form the logging circuit  66 . 
         [0031]    Notably, as illustrated in the exemplary blasting system  50 , the detonators  10   a ,  10   b ,  10   c , and  10   d  are connected in a series in the logging circuit  66 , as indicated by the numbers 1, 2, 3, and 4, while the detonators are connected in parallel pattern in the blast control circuit  62 . The parallel arrangement of the detonators in the blast control circuit  62  is exemplary only; various other patterns (serial, parallel, etc.) and combinations of such patterns may be employed, as is commonly understood by those skilled in the art. 
         [0032]    The leg wires  32   a ,  32   b  and the logging wires  38   a ,  38   b  of the detonators  10   a ,  10   b ,  10   c , and  10   d  may be connected to the blast lines  56   a ,  56   b , and the logging line  60  of the bus line  54  in any known manner. However, the present invention comprises a specially configured insulation displacement connector (IDC)  68   a ,  68   b ,  68   c ,  68   d , one for each detonator  10   a ,  10   b ,  10   c , and  10   d.    
         [0033]    A preferred embodiment of the inventive IDC will be described with reference to  FIGS. 3 and 4 . As the IDC&#39;s may be identically formed, only the IDC  68   a  will be described in detail. The IDC  68   a  comprises an enclosure or casing  70 . Though not shown in detail, the casing  70  preferably will be formed of non-conductive material and most preferably will be waterproof. The casing  70  may include a cover, not shown, that is openable to access the connection structures inside. 
         [0034]    The IDC  68   a  includes conductive elements configured to pierce the protective sheath on the various wires in order to establish an electrically conductive connection between the wires. To that end, the IDC  68   a  includes a first barb set  72  in the casing  70  for electrically connecting the first blast line  56   a  of the blast control circuit  62  ( FIG. 2 ) with the first leg wire  32   a  of the detonator  10 . A second barb set  74  is structured to electrically connect the second blast line  56   b  with the second leg wire  32   b  of the detonator  10 . The first and second barb sets  72  and  74  are designed to connect the leg wires without severing the blast lines. 
         [0035]    Referring still to  FIGS. 3 and 4 , the IDC  68   a  includes a third barb set  76  in the casing  70  for electrically connecting the logging line  60  of the logging circuit  66  ( FIG. 2 ) to the first logging wire  38   a  of the detonator  10  and a fourth a barb set  78  for electrically connecting the logging line to the second logging wire  38   b . As indicated above, in the preferred practice of the invention, the detonators are connected in series in the logging circuit  66 . To sever the logging line  60 , the IDC  68   a  includes a line cutter  82  positioned between the third and fourth barb sets  76  and  78  for electrically severing the logging line  60 . The line cutter preferably comprises a pair of blades  82   a  and  82   b.    
         [0036]    To facilitate the correct placement of the electrical conduits in the IDC  68   a , the casing  70  may include a channel for each conductor. As used here, “channel” denotes any structure that services to position the conductor in the casing. Thus, “channel” includes a groove, recess, snap ring, cradle, or other such structure, and the channel may be a continuous or discontinuous structure. For that reason, the channels are shown only in broken lines and only in  FIG. 3 . 
         [0037]    A indicated in  FIG. 3 , a first bus wire channel  86  is provided in the casing for receiving a section of the first blast line  56   a  of the blast control circuit  62 . Also included is second bus wire channel  88  for receiving a section of the second blast line  56   b , and a third bus wire channel  90  for receiving a section of the logging line  60  of the logging circuit  66 . A fourth channel  94  is formed in the casing for receiving a section of the first logging wire  38   a  of the detonator, and a fifth channel  96  is included for receiving a section of the second logging wire  38   b . Still further, a sixth channel  98  is configured for receiving a section of the first leg wire  32   a , and a seventh channel  100  is configured for receiving a section of the second leg wire  32   b.    
         [0038]    In this way, the interconnection of the leg wires and logging wires on each detonator can be quickly and correctly spliced with the three-line bus wire by placing the respective conductors in the appropriate channel. More importantly, the inventive IDC accomplishes this multi-wire connection while ensuring that the blast lines of the blast control circuit are not interrupted and that that the logging line of the logging circuit is effectively severed. It will be appreciated that the inventive IDC devices may be sold separately or as part of a detonator and connector assembly, as in most instances a connector will be needed for each detonator. 
         [0039]    Once the blast system  50  is fully assembled in the field, the detonators  10   a ,  10   b ,  10   c , and  10   d  are logged. As indicated, the blast machine  52  ( FIG. 2 ) and the control module  26  in each detonator are programmed to carry out an automated detonator logging operation that eliminates the need for personnel in the field. In accordance with the invention, the detonator logging operation includes the blast machine transmitting a unique detonator sequence number to each detonator. Each detonator accepts an assigned detonator sequence number from the blast machine in response to logging status from an immediately preceding detonator in the series. Then, the detonator posts a “logged” status flag for output to the immediately succeeding detonator in the series. 
         [0040]    The detonator logging operation is summarized in the flow diagram of  FIG. 5 . The detonator logging operation commences with the blast machine  52  powering up all the detonators  10   a ,  10   b ,  10   c , and  10   d , as indicated at block  102 . Next, at block  104 , the blast machine  52  begins the initialization process by transmitting an initialization command on the logging line  60  ( FIG. 2 ). Initially, only the first detonator  10   a  will respond to the “initialize” command, and the other detonators  10   b ,  10   c , and  10   d  will reject the command since they are not enabled. 
         [0041]    By means of the D2D communication on the logging circuit, as indicated at block  106 , the blast machine  52  will assign the first detonator  10   a  detonator sequence number 1, and the first detonator will confirm acceptance of the detonator sequence number assigned to it. The logged detonator  10   a  will then post its status as “logged” for signalling to the next detonator  10   b . The blast machine  52  then repeats the initialization command and sends the detonator sequence number 2 to the second detonator  10   b . Upon confirming the “logged” status of the immediately preceding detonator (in this case detonator  10   a ), the second detonator  10   b  accepts the sequence number “2” posts its status now as “logged,” which will then enable the next detonator for initialization. 
         [0042]    This process repeats until all detonators in the series have responded. When no further “initialized” signals are received from the logging circuit, the blast machine ends the detonator logging operation. At this point, the blast machine has associated a specific sequence number with each detonator allowing detonator-specific communication to execute other commands as necessary to complete the blast operation. 
         [0043]    Turning now to  FIG. 6 , the functional logic of the detonator logging operation performed by the control module  26  in the detonator  10  will be explained in more detail. At START  200 , the detonator gets power from the blast machine  52 . All initializing routines are run, and the detonator is ready to receive commands from the blast machine. The detonator sequence number and delay time data stored in the module&#39;s memory are reset to zero. 
         [0044]    At  202 , the detonator receives data from the blast machine  52 . This data includes the command signal to do specific processes, an assigned detonator sequence number, and the delay time data. At  204 , the detonator verifies whether the command is to commence the detonator logging operation. If the command is for logging, then at  206  the program determines if the assigned sequence number (“detonator #”) in its memory is zero or greater than zero. If the Detonator # is greater than zero or “no,” the detonator is already logged, and the program returns to  202  and for new command. 
         [0045]    If, at block  206 , the Detonator # in memory is zero or “yes,” then the program proceeds to block  208  and checks the data flag from the previous detonator, if any, at  216 . If the flag of the preceding detonator is not set, or the response to the query at  208  is “no,” the log command is not for this detonator, and the logic returns to  202  for the next command. If the flag at  216  is set, or the response to the query at  208  is “yes,” then the logging operation proceeds to block  210 , and the detonator stores the received sequence number in its memory along with the updated delay time data. 
         [0046]    Next, at block  212 , the detonator will set the data flag output connected to the next detonator in series. This “logged” status will be detected by the next detonator in series when it conducts its logging operation. Finally, after posting its “logged” status data flag, at  214  the detonator replies to the blast machine that the logging process is completed. 
         [0047]    At block  204 , if the initial response is “no,” that is, if the command is not for logging, the program proceeds to  218  and checks if the command is to commence the firing operation. If “no,” then the command is for another function, and the program proceeds to perform such other functions  220  as commanded and returns to the “receive data” station at  202 . If at  218 , the command is for firing or “yes,” the program proceeds to block  222 , and again queries the memory for the stored detonator sequence number. If the stored sequence number is zero, the detonator is not logged and the program returns to step  202  for further commands. If the stored sequence number is greater than zero, then the “logged” status is verified, and the program proceeds to execute the fire command at block  224  whereupon the operation is ended at  226 . 
         [0048]    With reference now to  FIG. 7 , the logic employed by the blast machine  52  in relation to the automatic detonator logging operation will be described. Commencing at START  300 , the blast machine  52  ( FIG. 2 ) is initialized and is ready to function. The blast machine assumes that that all the detonators  10   a ,  10   b ,  10   c , and  10   d  are connected in the logging circuit  66  in series. For example, if the blast pattern has multiple rows, as in subsequent embodiments described below, the machine assumes that the last detonator in the first row is connected to the first detonator in the second row, and so forth. 
         [0049]    At  302 , the blast machine receives input from the operator for the blasting operation. This data includes blast pattern, including how many rows of detonators, and how many detonators in each row (“holes per row”). This data also includes delay times for each detonator, including row-to-row delay time values and hole-to-hole delay time values. In particular, the data includes to total number of detonators in the blast pattern designated as “N T .” 
         [0050]    At  304 , in response to a LOG Command from the operator, the blast machine switches on the detonator power, and all the connected detonators are powered. The blast machines sends out a LOG command to each detonator in sequence along with the delay time data for that specific detonator. Additionally, before initiating the logging operation, the detonator&#39;s assigned sequence number “N S ” and the number of detonators logged “N L ” are reset to zero at block  306 . At block  308 , as the logging operation progresses, the blast machine incrementally increases the detonator sequence number N S  as each detonator is logged. 
         [0051]    As indicated, N S  is the sequence number of the detonator connected in the field. From the blast operation data input at step  302 , the blast machine computes the position of the detonator (row# and hole#) with this sequence number N S . The delay time for that detonator is computed using the delay time data from step  302 . For example, the following formula may be employed: 
         [0000]      Delay Time=((row#−1)×row delay)+((hole#−1)×hole delay)
 
         [0000]    where the row# and hole# start from 1. 
         [0052]    At step  312 , the blast machine sends the data to the detonators connected on the field. This data includes the command to log the detonator, the detonator number, and the respective delay time value. At step  314 , this data is received by the respective detonator on the field, and the detonator replies to the blast machine. The blasting machine will not proceed without a reply from the detonator at step  314 . If the response at block  314  is “yes,” the logic returns at  316  to step  308 , whereupon the detonator number N S  is ticked up and the operation proceeds to log the next detonator in the sequence. If no reply is received from the detonator at  314  after a predetermined interval of time, this indicates that all detonators have been logged, and the logic moves to step  318 . 
         [0053]    At  318 , after receiving no further replies from detonators in the field, the logic then compares the total number of detonators logged “N L ,” with the pre-programmed number of total detonators in the blast operation, N T , which was input at  302 . If N L  equals N T , the logic proceeds to step  320  and completes the rest of the blasting program. If N L  does not equal N T , the logic displays an error at  322  and returns to START  300  of the operation. 
         [0054]    At the completion of the logging operation, all the detonator in the blast operation are logged, each detonator has received and accepted its own unique detonator-specific sequence number. This number can be used by the blast machine to communicate with individual detonators to perform operations like diagnostics or modification of programmed delay time data etc. The remainder of the blast operation is carried out according to conventional procedures. 
         [0055]    In the previous embodiment, the control module  26  of the detonator  10  was programmed to include the detonator logging module, as previously described. In some instances, it may be desirable to provide an external or separate detonator logging unit. One preferred embodiment of an external detonator logging unit is shown in  FIGS. 8 and 8A , to which we now turn. In  FIG. 8 , the detonator logging unit  400  is shown electrically coupled to a conventional electronic detonator  402  forming a detonator-logging assembly  404  comprising an electronic detonator and the detonator logging unit. The exemplary detonator  402  comprises a hollow tubular shell  406  with a blind or closed end  408  and an opposite open end  410 . An explosive charge is contained in the blind end  408 . The explosive charge may include a base charge  412  and a primary explosive  414 . 
         [0056]    The detonator  402  includes a control module  416 . The control module  416  may be a microcontroller or programmable logic device and more preferably comprises an application-specific integrated circuit chip (ASIC). The control module  416  is programmed to communicate with the detonator logging unit  400 . The detonator logging unit  400  is equipped with terminals  418   a ,  418   b  ( FIG. 8A )) to electrically connect to the leg wires  420   a  and  420   b . The detonator  402  communicates with the blast machine (not shown in this figure) through the detonator logging unit  400 . The control module  416  is operatively connected to an igniter of any suitable type, such as the fuse head  418 , to initiate the detonation of the explosive charge. 
         [0057]    Although separate and self-contained, the detonator logging unit  400  is similar in its functions and programming to the logging operation of the electronic detonator  10  in the previous embodiment. To that end, the detonator logging unit  400  may comprise a logging module  424  contained in a suitable housing  426 . As indicated, the housing  426  includes terminals  418   a ,  418   b  by which the logging module  424  is operatively connectable to the leg wires  420   a  and  420   b  of the electronic detonator  402 . 
         [0058]    The detonator logging unit  400  may form part of a blast system  428  depicted in  FIG. 9  in a manner similar to the previous embodiment. The blast system  428  comprises a blast machine  430  that is connected with a plurality of detonator-logging units  400   a ,  400   b ,  400   c , and  400   d  by a three-wire bus line  432 . The bus line  432  comprises first and second blast lines  434   a  and  434   b  and a logging line  436 . The blast lines  434   a  and  434   b  connect the detonator-logging units  400   a ,  400   b ,  400   c , and  400   d  in a blast control circuit  440 , and the logging line  436  connects the detonator-logging units  400   a ,  400   b ,  400   c , and  400   d  in a logging circuit  442 . 
         [0059]    As best seen in  FIG. 8A , the detonator logging unit  400  comprises first and second logging wires  442   a  and  442   b  and first and second blast wires  444   a  and  444   b . As seen in  FIG. 8A , the first and second logging wires  442   a  and  442   b  have internal ends  446   a ,  446   b  operatively connected to the logging module  424 . The external ends  448   a  and  448   b  of the first and second logging wires  442   a  and  442   b  are outside of the housing  426  for connecting the logging module  424  to the logging module of the detonator logging unit associated with the immediately preceding electronic detonator in the logging circuit  442  ( FIG. 9 ) and the logging module of the of the detonator logging unit associated with the immediately succeeding electronic detonator in the logging circuit, as shown in  FIG. 9 . 
         [0060]    Referring still to  FIG. 8A , the first and second blast wires  444   a  and  444   b  have internal ends  450   a  and  450   b  operatively connected to the logging module  424  and external ends  452   a  and  452   b  outside of the housing  426  for connecting the detonator logging unit to the blast control circuit  440  ( FIG. 9 ). Thus, the detonator logging unit  400  is interposed between the leg wires  420   a  and  420   b  of the electronic detonator  402  and the blast circuit  440  ( FIG. 9 ). 
         [0061]    As indicated, the logging module  424  of the external detonator logging unit  400  is programmed to carry out the same logging operation as previously described in relation to the detonator  10 . However, now it will be appreciated that the external logging unit  400  conveniently may also function as a conventional surface connector. For example, positioned outside the shell as a programmable surface connector the unit  400  may operate as a “Hole to Hole delay” and “Row to Row delay,” as is done in conventional blast design using “Surface delay+DTH” combination. Still further, although not depicted in  FIGS. 8 and 9 , the logging units  400   a ,  400   b ,  400   c , and  400   d  may be connected to the bus wire  432  by using the IDC connectors, as previously described. 
         [0062]    The detonator logging operation for the blast system  428  ( FIG. 9 ) is summarized in the flow diagram of  FIG. 10 . The detonator logging operation commences with the blast machine  430  powering up all the detonator logging units  400   a ,  400   b ,  400   c , and  400   d , and associated detonators  402   a ,  402   b ,  402   c , and  402   d , as indicated at block  460 . Next, at block  462 , the blast machine  430  begins in the initialization process by transmitting an initialization command on the logging line  436  ( FIG. 9 ). Initially, only the first detonator logging units  400   a  will respond to the “initialize” command, and the other detonator logging units  400   b ,  400   c , and  400   d  will reject the command since they are not enabled. 
         [0063]    By means of the D2D communication on the logging circuit  442 , indicated at block  464 , the blast machine  430  will assign the first detonator-logging unit  400   a  detonator sequence number 1, and the first detonator logging unit  400   a  will confirm acceptance of the detonator sequence number and assign it to the detonator  402   a  connected to it. The logged detonator logging unit  400   a  will then post its status as “logged” and will set the data flag output connected to the next detonator-logging unit  400   b . The blast machine  430  then repeats the initialization command and sends the detonator sequence number 2 that will be accepted only by the detonator-logging unit  400   b . The second detonator-logging unit  400   b  accepts the sequence number “2” posts its status now as “logged,” which will then enable the next detonator-logging unit for initialization. 
         [0064]    This process repeats until all the detonator-logging units  400   a ,  400   b ,  400   c , and  400   d  in the series have responded after initiating the connected detonators  402   a ,  402   b ,  402   c , and  402   d , respectively. When no further “initialized” signals are received from the logging circuit, the blast machine ends the detonator logging operation. At this point, the blast machine has associated a specific sequence number with each detonator in the system allowing detonator-specific communications to execute other commands as necessary to complete the blast operation. 
         [0065]    The previously described blast systems  50  and  428  illustrate examples of blast patterns that comprise a single row of electronic detonators. However, many blast systems comprise detonators arranged in a plurality of rows. An example of such a blast pattern is illustrated in  FIG. 11 , to which attention now is directed. 
         [0066]    The multi-row blast system, designated generally at  500 , comprises three (3) rows R 1 , R 2 , and R 3  of four (4) detonators each. Each of the detonators is shown as part of a detonator-logging unit comprising a detonator and an external or surface detonator logging unit, as described above in connection with  FIGS. 8-10 . It will be understood that a multi-row blast system alternately could employ the detonators with the built-in logging module. The blast system  500  comprises a blast machine  502  interconnected in a blast control circuit  504  by first and second blast lines  506  and  508  and also interconnected in a logging circuit  510  by a logging line  512 . The blast lines  506  and  508  and logging line  512  form a three-wire bus line  516 , as in the previous embodiments. 
         [0067]    In accordance with the present invention, the multi-row blast system  500  further comprises a plurality of row logging units  520   a ,  520   b , and  520   c , including a row logging unit operatively associated with a different one of each of the plurality of rows R 1 , R 2 , and R 3 . As with the detonator logging units previously described, the row logging units  520   a ,  520   b , and  520   c , are interposed in the logging circuit  510  in series by the logging line  512 . The customized IDC connectors previously described may also be used to connect the row logging units  520   a ,  520   b , and  520   c  to the bus line  516 . The row logging units  520   a ,  520   b , and  520   c  provide row-to-row (“R2R”) communication similar to the detonator-to-detonator or D2D communication provided by the detonator logging units. 
         [0068]    Each of the row logging units  520   a ,  520   b , and  520   c  may comprise a housing and a row logging module in the housing. As these units are similar to the units  400  of the previous embodiment, they are not shown or described in detail. Each of the row logging units  520   a ,  520   b , and  520   c  is configured to execute a plurality of operations including a row logging operation. The blast machine  502  and the row logging units  520   a ,  520   b , and  520   c  carry out a row logging operation that corresponds to the detonator logging operation previously explained. 
         [0069]    The row logging operation includes accepting an assigned row sequence number (Row 1.0, Row 2.0, Row 3.0, etc.) from the blast machine  502  in response to row logging status from an immediately preceding row logging unit in the series of row logging units and posting row logging status for output to an immediately succeeding row logging unit in the series. Each of the row logging units  520   a ,  520   b , and  520   c  is configure to receive and store in its memory row logging data from the blast machine  502 . The row logging data from the blast machine  502  comprises an assigned row number that is zero or a number greater than zero. The row logging operation includes completing the row logging operation if the assigned row number in the memory is zero and ending the row logging operation if the assigned row number is greater than zero. 
         [0070]    The row logging operation includes checking for row logging status posted by the immediately preceding row logging unit in the logging circuit and ending the row logging operation if no logging status is detected for the immediately preceding row logging unit. If a “logged” status is detected for the immediately preceding row logging unit, the row logging operation is completed by accepting the assigned row number received from the blast machine, posting a “logged” status for output to an immediately succeeding row logging unit in the logging circuit, and signalling to the blast machine that the row logging operation is completed. Preferably, the blast machine is configured to complete the row logging operation prior to starting the detonator logging operation. 
         [0071]    The detonator logging operation for the blast system  500  ( FIG. 11 ) is summarized in the flow diagram of  FIG. 12 . The detonator logging operation commences at block  530  with the blast machine  502  powering up all the detonator logging units and associated detonators of the detonator-logging assemblies. Next, at step  532 , the blast machine  502  initializes the row logging or R2R units. Then, at block  534 , the blast machine  502  initializes the detonators, one row at a time, using the D2D detonator logging units. Thus, the blast machine  502  in this embodiment is configured to complete the row logging operation prior to starting the detonator logging operation. 
         [0072]    Once all detonator logging units and row logging units have been successfully logged, the blast machine is able to use the unique identifier for unit to communicate with individual logging units and detonators to perform the blasting operation or other functions. It should be noted that the identifier assigned to each detonator indicates which row the detonator is in and what number the detonator is the row. That is, the assigned identifier should contain the row and the hole numbers. For example, the second detonator in the third row will be identified as number 3.2 
         [0073]    Now it will be appreciated that the present invention provides a system and method by which the process of logging detonators in a blast operation is made more safe and more efficient. In addition to the conventional blast control circuit, the system includes a logging circuit. Regardless of the blast pattern of the detonators, the logging circuit connects the detonators in a series. 
         [0074]    The first detonator in the series, that is, the detonator connected directly to the blast machine, will identify itself as the first detonator in the circuit and then activate the next detonator in the series. The second detonator, then, turn will tag itself as detonator number two and activate the next in the circuit in a relay-like protocol. In this way, each detonator becomes associated with a unique identifier, which is its sequence number in the blast pattern. The blast machine can then use the unique identifiers to communicate with individual detonators. 
         [0075]    The embodiments shown and described above are exemplary. Many details are often found in the art and, therefore, many such details are neither shown nor described herein. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present invention have been shown in the drawings and described in the accompanying text, the description and drawings are illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of the parts, within the principles of the inventions to the full extent indicated by the broad meaning of the terms of the attached claims. The description and drawings of the specific embodiments herein do not point out what an infringement of this patent would be, but instead provide an example of how to use and make the invention. Likewise, the abstract is neither intended to define the invention, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. Rather, the limits of the invention and the bounds of the patent protection are measured by and defined in the following claims.