AUTOMATIC POS LOOP SWITCHING

Abstract: A POS loop switching apparatus includes a switching circuit (l5) for selectively connecting first and second transmission lines, to which at least one Point Of Sales (POS) terminal (l8A, l8B) is connected, and first and second file control means (llA, llB) for periodically supplying a control signal, so as to constitute at least one closed loop, and switch control means (l6A, l6B, l7) for supplying a first switching signal to a switching circuit (l5), in response to control signals from the first and second file control means (llA, llB), to cause the switching circuit (l5) to connect the first and second file control means (llA, llB) respectively to the first and second transmission lines, thereby to consti­ tute first and second closed loops, and when one of the first and second file control means (llA, llB) does not generate a control signal over a predetermined period of time, for supplying a second switching signal to the switching circuit (l5), to cause the switching circuit (l5) to connect one of first and second transmission lines connected to the file control means (llA or llB) which does not generate the control signal, to the other file control means (llB or llA), so as to constitute a new closed loop by the transmission line, the other file control means (llB or llA), and the other transmission line which was connected to the other file control means (llA or llB).

Description: The present invention relates to an automatic POS loop switching apparatus including a plurality of file control sections to which a plurality of Point Of Sales (POS) loops are connected, by means of a switching circuit. Some POS systems used by the distribution industry have two file control sections, lA and lB, and POS loops, 4A and 4B, obtained by connecting a plurality of POS terminals 2A and 2B respectively to sections lA and lB via transmission lines 3A and 3B, so as to form closed loops, as shown in Fig. l. When, in a POS system of this type, an article code of an item on sale is input to, for example, terminal 2A and loop 4A, by means of, say, a keying operation, the article code together with an inherent address are supplied, as an inquiry signal, to section lA. Section lA specifies the POS terminal in accordance with the inherent address thereof, and supplied article data such as the name of the item and its unit price, corresponding to the received article code, to terminal 2A. Terminal 2A executes sales registration processing in accordance with the article data received, and supplies sales data such the as the number of solid items and sales amount to section lA. Section lA totals the received sales data in a totaling file, in units of, for example, article codes. In addition, each data is generally transmitted between sections 1A and 1B and terminals 2A and 2B, in synchronism with a polling signal (control signal) supplied at a constant period from sections 1A and 1B. However, the POS system having the above arrangement has the following problem: When one of sections 1A and 1B malfunctions, terminal 2A or 2B which constitutes loop 4A or 4B, connected to the malfunctioning one of sections 1A and 1B, cannot then inquire about article data to the affected section 1A or 1B. In short, therefore, terminal 2A or 2B corresponding to the malfunctioning section 1A or 1B cannot perform sales registration processing. From EP 0082225 a business system with terminals is known, each of which is attached to two structures supported by two controllers, respectively. Selected terminals can be switched from one loop to another to couple two loops together and to alter the loop controller allegiance. This requires redundant transmission lines since the terminals are physically connected to two loops by means of their communication controllers. USP 4,169,288 discloses a redundant memory for POS system which is not directed to provision of two processing units each used for the other in case of malfunction of one of them. Consequently the document does not disclose switching circuit means for handling of this case. It is an object of the present invention, as claimed, to provide an automatic POS loop switching apparatus which can automatically switch a POS loop connected to a malfunctioning file control section to one which is operating normally, so that all the POS terminals can continue to be used in spite of the malfunctioning of one of the file control sections, thereby improving the reliability of the entire system. The above object can be achieved by an automatic POS loop control apparatus comprising: a plurality of transmission lines, to each of which at least one POS terminal is connected; a plurality of file control sections for periodically supplying a control signal; a switching circuit for selectively connecting the transmission lines and the file control sections so as to constitute at least one closed loop; and a switch control circuit for supplying a first switching signal to the switching circuit, in response to output signals from the file control sections, so that the switching circuit connects the file control sections to the corresponding transmission lines, thereby to constitute a plurality of closed loops, and when one of the file control sections does not generate a control signal over a predetermined period of time, for supplying a second switching signal to the switching circuit, so that the switching circuit connects one of the transmission lines connected to the file control section which has not generated a control signal to another file control section, in order to cause the transmission line, the other file control section, and the other transmission line connected thereto to constitute a new closed loop. According to the present invention, even when a file control section malfunctions, a transmission line connected thereto can be disconnected therefrom and inserted into a closed loop constituted by another, fully functioning, file control section and its corresponding transmission line. As a result, an article code from a POS terminal connected to the inserted transmission line can then be processed by the properly functioning file control section. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. l is a schematic view of a POS system including a plurality of POS loops; Fig. 2 is a schematic view of a POS system including a POS loop switching apparatus according to an embodiment of the present invention; Fig. 3 is a circuit diagram showing in detail a switching circuit of the POS loop switching apparatus shown in Fig. 2; Fig. 4 is a circuit diagram of a malfunction detector of the POS loop switching apparatus shown in Fig. 2; Fig. 5 is a circuit diagram of a switch control circuit of the POS loop switching apparatus shown Fig. 2; and Figs. 6 and 7 are circuit diagrams showing states of a switching circuit when different file control sections in the POS system shown in Fig. 2 malfunction. Fig. 2 is a block diagram of an automatic POS loop switching apparatus according to an embodiment of the present invention. The apparatus includes file control sections llA and llB respectively controlling POS loops l2A and l2B. Sections llA and llB are connected to loops l2A and l2B respectively via signal output lines l3A and l3B and signal input lines l4A and l4B for transmitting control signals TXA, TXB, RXA, and RXB, and switching circuit l5. Detectors l6A and l6B are connected to lines l3A and l3B so as to detect whether sections llA and llB are malfunctioning, detection being based on whether a control signal (polling signal) is supplied from each of sections llA and llB, at a predetermined interval. Malfunction detection signals FEA and FEB are respectively supplied from detectors l6A and l6B to switch control circuit l7 for switching connections between sections llA and llB and loops l2A and l2B. In accordance with the levels of signals FEA and FEB input thereto, circuit l7 supplies control signals Rl, R2, R3, and R4 to circuit l5, so as to control 4 relays which constitute circuit l5. A plurality of POS terminals l8A and l8B are respectively connected to loops l2A and l2B. Sections llA and llB respectively have memory areas (not shown) corresponding to the inherent addresses of terminals l8A and l8B, and write article data in the memory areas specified by these addresses, regardless of whether an article code is supplied to terminal l8A or l8B. As is shown in Fig. 3, circuit l5 is constituted by 4 relays l9, 20, 2l, and 22 respectively driven by signals Rl, R2, R3, and R4 output from circuit l7. Relays l9, 20, 2l, and 22 respectively have two switches l9A and l9B; 20A and 20B; 2lA and 2lB; and 22A and 22B, simultaneously driven by signals Rl to R4. Switches l9A to 22B are connected to first SW terminal FT when signals Rl to R4 are at H level, and are connected to second SW terminal ST when signals Rl to R4 are at L level. Normally, signals Rl to R4 are set at H level; therefore, switches l9A to 22B are connected to terminal FT. Common terminals CT of switches l9A and 20A of relays l9 and 20 at the side of section llA are respectively connected to lines l3A and l4A, and common terminals CT of switches l9B and 20B are connected to the transmission lines of loop l2A. Similarly, common terminals CT of switches 2lA and 22A of relays 2l and 22 at the side of section llB are connected to lines l3B and l4B, and common terminals CT of switches 2lB and 22B are connected to the transmission lines of loop l2B. Terminals FT of the switches of relays l9 to 22 are connected to each other. Terminals ST of contacts l9B, 2lA, and 22A are connected to each other, and terminals ST of switches l9A, 20A, and 22B are connected to each other. Terminals ST of switches 20B and 2lB are connected to each other. Detectors l6A and l6B shown in Fig. 2 are arranged as shown in Fig. 4. That is, a control signal (TXA or TXB) supplied from section llA or llB and flowing through line l3A or l3B is input directly to one input terminal of exclusive OR circuit 23, via signal input terminal SIT, and is also input to the other input terminal of circuit 23 via inverter 24 and integrating circuit 25 including a resistor and a capacitor. An output signal from circuit 23 is input to a trigger terminal (T) of retrigger type monostable multivibrator 26. In response to a trigger signal of H level at its terminal T, multivibrator 26 supplies a signal, which is at H level for a predetermined time (limit time T) from the input timing, from Q terminal to signal output terminal SOT. In this embodiment, limit time T is set to 5 seconds. Therefore, when the level of signal TXA or TXB input to terminal SIT of detector l6A or l6B varies, a pulse signal of H level is output from circuit 23. As a result, multivibrator 26 is operated to output a signal of H level, via terminal SOT, for only 5 seconds after the signal level changes. That is, when the level of the control signal changes during a period of 5 seconds or less, an output signal is always kept at H level. However, when the control signal is not output for more than 5 seconds, corresponding detector l6A or l6B outputs a signal FEA or FEB at L level. Note that during normal operation, the control signal (polling signal) supplied from sections llA and llB is not stopped for more than 5 seconds. An arrangement of switch control circuit l7 is as shown in Fig. 5. Signals FEA and FEB supplied from detectors l6A and l6B are input to one input terminal of each of OR gates 27A and 27B, respectively, and are also input to the other input terminal of each of the other OR gates 27A and 27B, via inverters 28A and 28B. Output signals from OR gates 27A and 27B are respectively input to open collector type inverters 29A and 29B. Output signals from inverters 29A and 29B are input to circuit l5, as signals Rl and R4, respectively. In addition, output signals from inverters 29A and 29B are respectively output as control signals R2 and R3, via diodes 30A and 30B having the polarities shown in Fig. 5. Therefore, when both sections llA and llB of circuit l7 of Fig. 5 are operating normally, i.e., when signals FEA and FEB are both at H level, the output signals from gates 27A and 27B are both set at H level, so that signals Rl to R4 may also be set at H level. When only section llA malfunctions, then only signal FEA goes to L level. In this case, since an output signal from gate 27A is set at L level and an output signal from gate 27B is set to H level, signals Rl to R3 are set at L level, and only signal R4 is set at H level. Conversely, when only section llB malfunctions, signals R2 to R4 is set to L level, and only signal Rl is set to H. Note that when sections llA and llB both malfunction at the same time, signals FEA and FEB are both set to L level, and output signals from gates 27A and 27B are both set to H level, so that signals Rl and R4 remain at H level, as in the case where sections llA and llB are both operating normally. An operation of the automatic POS loop switching apparatus having the above arrangement will now be described below. First, when they are operating normally, file control sections llA and llB supply control signals (polling signals) within a period of limit time ( T = 5 sec) to POS loops l2A and l2B, so that malfunction detection signals FEA and FEB of L level are not output from detectors l6A and l6B. This causes control signals Rl to R4 of H level to be supplied from switch control circuit l7. Therefore, relays l9 to 22 of switching circuit l5 are not operated. As a result, as is shown in Fig. 3, relay switches l9A to 22B remain connected to first SW terminals FT. At this time, sections llA and llB are connected to loops l2A and l2B, respectively. In this case, in a manner similar to the conventional case, article codes input to POS terminals l8A and l8B, together with inherent addresses, are supplied to sections llA and llB, respectively, and are processed therein. When only section llA malfunctions, a control signal is no longer generated therefrom. As a result, a malfunction detection signal FEA at L level is output from detector l6, five seconds after section llA has begun to malfunction. Accordingly, signals Rl to R3 supplied from circuit l7 are set to L level, and only signal R4 remains at H level. Therefore, as is shown in Fig. 6, relays l9, 20, and 2l of circuit l5 are operated to connect switches l9A, l9B, 20A, 20B, 2lA, and 2lB to second terminals ST, and switches 22A and 22B of relay 22 are kept connected to terminals FT. However, as is shown in Fig. 6, signal output line l3A and signal input line l4A of malfunctioned section llA are completely disconnected from loop l2A. At the same time, loops l2A and l2B are connected in series via switches 20B and 2lB. Two POS loops are connected to fully functioning section llB, as a new single POS loop, so as to form a closed loop. Thus, a normal sales registration operation can continue to be performed at terminals l8A of loop l2A. That is, article codes input to terminals l8A are supplied, together with inherent addresses, to section llB, and are processed therein as in section llA. In this case, article codes input to terminals l8B can be processed, in the same manner, in section llB. Conversely, when only section llB malfunctions, signal FEB of L level is generated from detector l6B, so that signals R2 to R4 output from circuit l7 are set to L level and only signal Rl is set to H level. In this case, as is shown in Fig. 7, relays 20, 2l, and 22 of circuit l5 are operated to connect switches 20A, 20B, 2lA, 2lB, 22A, and 22B to terminals ST, and switches l9A and l9B of relay l9 are kept connected top terminals FT. As a result, malfunctioning section llB is disconnected from loop l2B, and loops l2A and l2B are connected to section llA, which is operating normally. Therefore, article codes input to terminal l8A or l8B are supplied, together with inherent addresses, to section llA and are processed therein. Note that when sections llA and llB both malfunction, relays l9 to 22 of circuit l5 are not operated. According to the automatic POS loop switching apparatus having the above arrangement, when either of sections llA or llB malfunctions, the POS loop connected to the malfunctioning file control section is automatically switched to the other, fully functioning, file control section, substantially at the time the malfunction occurs. Therefore, even when one of the file control sections malfunctions, POS terminal l8A or l8B, which constitutes POS loop l2A or l2B connected to the malfunctioning file control section, can continue to perform normal sales registration operations. Thus, the reliability of the entire POS system is significantly improved. Note that the present invention is not limited to the above embodiment. For example, latching relays may be used as relays constituting switching circuit l5. By using the latching relays, even when one of the file control sections malfunctions and the power source of the entire system is cut off with both the POS loops connected to the other control section, the connection state of circuit l5 can be maintained at that in effect prior to the power source being cut off, when the power source is tuned on again. In addition, three or more file control sections may be used, and POS loops may be connected to these file control sections.

Claims: A POS loop switching apparatus characterized by comprising: switching circuit means (15) for selectively connecting first and second transmission lines to first and second file control means (11A, 11B) which each periodically generate a control signal to be supplied to the transmission line connected thereto, each of said first and second transmission lines being coupled to at least one point Of Sales (POS) terminal (18A, 18B) which performs data transmission under the control signal; and switch control means (16A, 16B, 17) coupled to said switching circuit means (15), for causing said switching circuit means (15) to connect said first and second transmission lines respectively to said first and second file control moans (11A, 11B) to constitute first and second closed loops when the first and second file control means (11A, 11B) operate normally, and for, when one of said first and second file control means (11A, 11B) malfunctions, causing said switching circuit means (15) to connect said first and second transmission lines to the other file control means (11A, 11B) to constitute a new closed loop. An apparatus according to claim 1, characterized in that said switch control means includes first and second malfunction detecting means (16A, 16B) respectively connected to said first and second file control means (11A, 11B), each for generating a malfunction detection signal when a control signal is not generated from a corresponding file control means (11A, 11B) over a predetermined period of time; and switch control circuit means (17) connected to said first and second malfunction detecting means (16A, 16B), for causing said switching circuit means to connect said first and second transmission lines to the second file control means (11B) in response to a malfunction detection signal from said first malfunction detecting means (16A), and to said first file control means (11A) in response to a malfunction detection signal from said second malfunction detecting means (16B). An apparatus according to claim 2, characterized in that: said first and second file control means (11A, 11B) generate control signals at an interval of time T; and said first and second malfunction detecting means (16A, 16B) are signal generating circuits for generating a signal of a first predetermined level during a normal operation, and generating an output signal of a second predetermined level for a longer period than time T, in response to a control signal. An apparatus according to claim 1, 2, or 3, characterized in that said switching circuit means (15) includes a plurality of relay switches (19A to 22B).

Inventors: MUROI, HIDENORI
Applicants: TOKYO ELECTRIC CO., LTD.
Application year: 1987
Main classification: G06F15
IPC codes: G07G1, G06F11