JP4238705B2 - Safety controller - Google Patents

Description

The present invention relates to a safety controller, and more particularly, relates to a suitable safety controller safety circuit of the machine equipment such as machine tools and industrial robots.

  Conventionally, for example, in order to ensure occupational safety at a production site, a safety circuit using a relay unit incorporating a plurality of electromagnetic relays, that is, a machine tool, an industrial robot, etc. only when safety is ensured A safety circuit that supplies power to the power of mechanical equipment has been constructed (see, for example, Patent Document 1).

Such a relay unit monitors the state of the safety circuit based on the input signals from safety switches such as emergency stop switches and safety area sensors such as safety door switches. As long as it is shut off and the cause of the failure is not removed, it has a function of not restarting the mechanical equipment.
JP 2003-140702 A

  In a system using a relay unit incorporating such an electromagnetic relay, a safety circuit is constructed by a relay sequence. Therefore, logic is assembled by wiring, and as the number of machine tools to be controlled increases, the number of wiring increases. It becomes complicated and the design is not easy.

The present invention was made in view of such points, thereby reducing the number of wirings, and an object thereof is constructed of system provides an easy safety controller.

  In order to achieve the above object, the present invention is configured as follows.

That is, the safety controller of the present invention is a safety controller that controls the operation of a mechanical facility by giving a safety output to a safety output control target based on an input from an input device, and provides a semiconductor output as the safety output. An output unit, a control unit that controls the safety output according to a program based on the input from the input device , and an abnormality detection unit that detects an abnormality, and includes an electromagnetic relay according to the safety output A plurality of extension units that output relay outputs to the safety output control target can be sequentially connected to the safety controller via the extension units, and the abnormality detection unit is configured to connect the safety unit configured by connecting the extension units. Feedback from the controller to the safety controller via the extension unit Based on the feedback input of the-loop, and detects an abnormality.

  Here, the input device refers to a device that gives an input to the safety controller, such as an emergency stop switch, a safety door switch, a safety limit switch, and a safety light curtain.

  The safety output control target refers to a target controlled by a safety output that is an output of the safety controller, for example, a magnet contactor, a motor controller, a variable motor, a PLC, or the like.

  Mechanical equipment refers to various machine tools, industrial robots, and the like.

  Also, controlling the operation of the mechanical equipment means starting / stopping control of the mechanical equipment, operation speed control, and the like.

  An extension unit is a unit that is connected to the safety controller, has a built-in electromagnetic relay, and outputs a relay output corresponding to the safety output of the safety controller to the safety output control target, increasing the number of output points. That is, a unit for expansion.

  Moreover, abnormality refers to, for example, contact welding of an electromagnetic relay of an extension unit.

  According to the present invention, since the safety output unit that provides the safety output that is a semiconductor output to the safety output control target and the control unit that controls the safety output according to the program are provided, the conventional relay unit including the electromagnetic relay is provided. Thus, it is not necessary to build a safety circuit with a relay sequence, the number of wires can be reduced, and software can be used even when the manufacturer wants to change a part of the system according to the user's request. It will be possible to easily cope with this change.

  Moreover, by connecting an expansion unit with a built-in electromagnetic relay to the safety controller, the number of output points can be easily increased, and an abnormality is detected based on a feedback input given through the expansion unit. For example, it is possible to detect an abnormality such as contact welding of an electromagnetic relay of an extension unit and prohibit the operation of mechanical equipment.

In one embodiment of the present invention , a termination resistor is attached to the last-stage expansion unit among the plurality of expansion units connected in sequence, and the feedback loop is configured via the termination resistor. .

According to this embodiment, an extension unit is connected to the safety controller, and a plurality of extension units are sequentially connected such that another extension unit is connected via the extension unit. By attaching a terminating resistor to the farthest extension unit, the feedback loop can be configured. When multiple extension units are connected, contact welding of each extension unit and feedback loop Abnormalities can be detected.

In a preferred embodiment of the present invention, the electromagnetic relay has an a contact and a b contact interlocking with each other, and one of the two contacts is an output contact for outputting the relay output, The contact is connected in the feedback loop, and the abnormality detection unit detects at least one of welding of the output contact of the electromagnetic relay and abnormality of the feedback loop.

  Here, the abnormality of the feedback loop means, for example, disconnection or short circuit.

  According to this embodiment, it is possible to detect at least one of abnormalities such as welding of the output contact, disconnection of the feedback loop, and short circuit based on the feedback input.

  Here, the connection output refers to an output used for connection between the safety controller and another safety controller.

  Here, “for logical connection” refers to a connection for connecting other safety controllers connected to the safety controller in association with logic such as logical product or logical sum.

  Here, the output state refers to a safe-side output state in which the operation of the machine facility is allowed or a dangerous-side output state in which the operation of the machine facility is prohibited.

  As described above, according to the present invention, a safety output unit that gives a safety output that is a semiconductor output to a safety output control target, and a control unit that controls the safety output according to a program based on an input from an input device are provided. Therefore, unlike conventional relay units with built-in electromagnetic relays, it is not necessary to build a safety circuit with relay sequences, and the number of wires can be reduced. Even if it is desired to change a part of the software, it can be easily handled by changing the software.

  In addition, by connecting an extension unit with built-in electromagnetic relay to the safety controller, the number of output points can be easily increased, and abnormalities such as contact welding of the extension unit's electromagnetic relay can be detected to operate machine equipment. Can be prohibited, and a high safety level can be secured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a system using a safety controller according to an embodiment of the present invention.

  The safety controller of this embodiment constitutes a safety circuit that supplies power to the power of machine equipment such as machine tools and industrial robots (not shown) only when safety is ensured.

  The safety controller of this embodiment is connected to a single function unit 3 to which an input device such as the emergency stop switch 2 is connected, and to an input device such as the safety door switch 1 as well as to the single function unit 3. The high function unit 4 is provided, and a plurality of extension units 5 can be connected to the high function unit 4 via a cable 6.

  The single-function unit 3 receives input from an input device such as the emergency stop switch 2 and outputs safety to a magnetic contactor as a safety output control target for supplying / cutting off electric power to a motor that drives a machine tool or the like And an internal safety output as an output for logical connection to the high-function unit 4.

  Here, the logic connection output means an output for logically connecting the single function unit 3 that outputs the logic connection output and the high function unit 4 to which the logic connection output is given.

  In this embodiment, the safety output output from the single function unit 3 to the safety output control target and the logical connection output have the same output state, that is, the safety output controls the operation of the mechanical equipment. When the safety-side output state is allowed, the logical connection output is also the safe-side output state. When the safety output is a dangerous-side output state that prohibits the operation of the mechanical equipment, the logical connection output Becomes the dangerous output state.

  Therefore, an output for logical connection that has the same output state as an original safety output for a safety output control target such as a magnetic contactor is called an internal safety output.

  The high-function unit 4 is provided with inputs from input devices such as an emergency stop switch and safety door switch 1 and an internal safety output output from the single-function unit 3 and the preceding high-function unit 4 as internal safety inputs. Outputs safety output to a magnetic contactor, etc., as a safety output control target that supplies and cuts off electric power to a motor that drives a machine, etc., and an internal safety output as an output for logical connection to a high-performance unit 4 in the subsequent stage. is there.

  Similarly to the above, the internal safety output, which is a logical connection output output from the high function unit 4, is also an output for logically connecting the preceding high function unit 4 and the subsequent high function unit 4.

  Further, the safety output output from the high-function unit 4 to the safety output control target and the internal safety output have the same output state. The high-function unit 4 can output a safety instantaneous output and a safety off-delay output, but the internal safety output is in the same output state as the safety instantaneous output.

  Here, the instantaneous safety output is a safety output that instantly switches to the dangerous side when the safety input switches from the safe side to the dangerous side when the safety output is on the safe side. Is the safety that switches to the dangerous side with a delay after continuing the safe state for the set time when the safety input switches from the safe side to the dangerous side when the safety output is on the safe side The output.

  In FIG. 1, the internal safety output given from the single-function unit 3 to the high-function unit 4 and the internal safety output given from the preceding high-function unit 4 to the subsequent high-function unit 4 are indicated by broken arrows. However, in this embodiment, the high function unit 4 is given an internal safety output from either the single function unit 3 or the preceding high function unit 4.

  The extension unit 5 is connected to the high-function unit 4 via the cable 6, and the safety output synchronized with the high-function unit 4 is used as a safety output control target for supplying / cutting off power for driving a machine tool or the like. This is output to a magnet contactor or the like.

  The single-function unit 3 is equipped with a CPU that constitutes a control unit as will be described later, and can input two safety inputs, as well as two safety instantaneous outputs that are semiconductor outputs (transistor outputs) and one internal safety output. Can be output. In this embodiment, the internal safety output for logical connection is the internal safety output for AND connection. The two safety inputs are given inputs from one emergency stop switch or the like for duplication according to safety standards.

  Further, the single function unit 3 can output a monitor output synchronized with the instantaneous safety output and an error output at the time of an internal error. Further, the single function unit 3 can input a feedback / reset input.

  As shown in the front view of FIG. 2, the single-function unit 3 includes a plurality of input / output terminals 7 on the top and bottom, as well as a power source (PWR), an error state (ERR), and safety inputs 1 and 2 (T1 , T2) and a safety instantaneous output (EI) state are respectively provided with a display unit 8 for displaying with LEDs.

  Like the single function unit 3, the high function unit 4 is equipped with a CPU as a control unit, and can input two safety inputs and one internal safety input, and two semiconductor outputs (transistor outputs). An instantaneous safety output, two safety off-delay outputs, and one internal safety output as an output for logic connection. In this embodiment, an internal safety output for AND connection can be output.

  As with the single function unit 3, the two safety inputs are given inputs from one emergency stop switch, one safety door switch, or the like for duplication.

  One internal safety input is an input of the internal safety output from the single-function unit 3 or the preceding high-function unit 4, and this internal safety input causes the single-function unit 3 or the preceding high-function unit 4 to perform logic. Connection In this embodiment, an AND connection is made.

  That is, in this embodiment, this internal safety input and the two safety inputs of the high-function unit 4 are logically connected by AND, and the input state of the internal safety input is a safe side state. And when the input state of two safety inputs is the safe input state, the safe output of the safe output state is output.

  Further, the high-function unit 4 can output a monitor output synchronized with the instantaneous safety output and an error output at the time of an internal error. Further, the high-function unit 4 can input a feedback / reset input.

  As shown in the front view of FIG. 3, the high-function unit 4 includes a plurality of input / output terminals 9 at the top and bottom, as well as a power source (PWR), an error state (ERR), and safety inputs 1 and 2 (T1 , T2), an internal safety input (AND), a feedback input (FB), a safety instantaneous output (EI), and a safety off-delay output (ED). The high-function unit 4 includes a connector 11 for connecting the extension unit 5. The connector 11 of the cable 6 shown in FIG. Can be connected to. When the extension unit 5 is not connected, a termination connector having a termination resistance described later is attached to the connector 11.

  Via this connector 11 and the cable 6, safety instantaneous output, safety off-delay output, feedback input / output of the extension unit 5, and ground signals are exchanged.

  Further, as shown in the rear view of FIG. 4, the high-function unit 4 has an opening formed in a portion to be mounted on the DIN rail, and the dip switch 12 and the rotary switch 13 are arranged so as to face the opening. The internal safety input for logical connection is set to be valid or invalid, and the off delay time is set.

  When the invalidity of the internal safety input for logical connection is set, the internal safety input given from the other units 3 and 4 is invalidated and the logical connection is not performed.

  The extension unit 5 is added as necessary when the number of output points is insufficient with the high-function unit 4 alone, and a plurality of, in this embodiment, two electromagnetic relays are incorporated. Each electromagnetic relay includes three a contacts for output and b contacts that are linked to the a contacts. This extension unit 5 has an instantaneous type that outputs three safety outputs, which are relay outputs in synchronization with the safety instantaneous output from the high-function unit 4, and a relay output in synchronization with the safety off-delay output from the high-function unit 4. There is an off-delay type that outputs three safety outputs.

  As shown in the front view of FIG. 5, the extension unit 5 includes a plurality of input / output terminals 14 on the upper and lower sides, as well as a power source (PWR), an error state (ERR), a safety instantaneous output (EI), or a safety A display unit 15 for displaying each state of the off-delay output (ED) with LEDs is provided. The extension unit 5 includes a high-function unit 4 or a connector 16 for connecting the extension unit 5. The connector 16 of the cable 6 shown in FIG. Alternatively, the extension unit 5 is connected.

  Note that a termination connector having a termination resistance described later is attached to the connector 16 of the extension unit 5 in the final stage.

  FIG. 6 is a block diagram of the high-function unit 4. In the same figure, 17 and 18 are two 1st and 2nd CPU which comprises a control part, and each CPU17 and 18 performs the same process, and is duplexed. The CPUs 17 and 18 communicate with each other for synchronizing software processing via an inter-CPU communication port.

  20 is a non-volatile memory for storing the setting contents from the setting switch 19 such as the above-described dip switch, 21 is an LED for displaying each state such as the power supply (PWR) and error state (ERR), and 22 is a delay IC. The watchdog timer 23 used is a monitoring circuit that monitors the state of the power supply circuit 24 that supplies power to each section.

  Reference numerals 25 and 26 each represent one system of duplicated safety inputs. For example, inputs from one safety door switch are given. Reference numeral 27 denotes a reset input circuit to which a feedback input or a reset input is given.

  28 is an AND input circuit to which an internal safety input as a logical connection input from the single-function unit 3 or the preceding high-function unit 4 is given, and 29 and 30 are RS232C circuits and a changeover switch for communication with an external personal computer or the like. is there.

  31 is an instantaneous safety output circuit, 32 is an off-delay safety output circuit, 33 is a duplex output line control circuit, and 34 is an internal safety output circuit that outputs an internal safety output to the subsequent high-function unit 4 , 35 is a monitor output circuit that outputs an instantaneous safety output for monitoring to a programmable controller (PLC), etc., 36 is an error output circuit that gives an error output when an internal error occurs, and 37 is a connector for connecting the extension unit 5. .

  The first and second CPUs 17 and 18 as the control unit are configured to output the safety output circuits 31 and 32 and the internal circuits according to a program based on the safety input from the safety input circuits 25 and 26 and the internal safety input from the AND input circuit 28. The safety output circuit 34 is controlled to control the safety output and the internal safety output which are semiconductor outputs (transistor outputs). The internal safety output circuit 34 includes a transistor for semiconductor output.

  Further, the first and second CPUs 17 and 18 as control units have a function as an abnormality detection unit that detects an abnormality such as welding of the output contact of the extension unit 5 as described later.

  FIG. 7 is a block diagram showing the configuration of the instantaneous safety output circuit 31, the off-delay safety output circuit 32, and the output line control circuit 33 of FIG. 6, and parts corresponding to those in FIG. A sign is attached. In FIG. 7, the signal from the first CPU 17 and the signal to the first CPU 17 are indicated by dashed arrows, and the signal from the second CPU 18 and the signal to the second CPU 18 are indicated by dashed-dotted arrows, respectively. Show.

  The instantaneous safety output circuit 31 includes two instantaneous output control units 38 and 39, and the off-delay safety output circuit 32 includes two off-delay output control units 40 and 41. Each of the output control units 38 to 41 includes a semiconductor output transistor.

  The output line control circuit 33 for duplexing the safety output includes a driving signal S1, S2 from the first and second CPUs 17, 18, a WDT signal from the watchdog timer 22, and a monitoring circuit 23 for monitoring the power supply circuit 24. PSM signals are respectively provided.

  When the driving signals S1 and S2 are both turned on, a voltage is applied to the power supply line VL and power is supplied to the output control units 38 to 41.

  The WDT signal from the watchdog timer 22 is also given to the output control units 38 to 41. When the watchdog timer 22 is not reset, this WDT signal is turned off and all the output control units 38 to 41 are turned on. Therefore, the safety output can be turned off, which is a danger side prohibiting the operation of the mechanical equipment, and safety can be ensured.

  The PSM signal from the monitoring circuit 23 for monitoring the power supply is also given to the output control units 38 to 41. When a power supply abnormality is detected, the PSM signal is turned off and all the output control units 38 are turned off. The safety output of .about.41 is turned off, which is a danger side prohibiting the operation of the mechanical equipment, and safety can be ensured.

  The output line control circuit 33 outputs monitoring signals S4 and S5 to the first and second CPUs 17 and 18, respectively. The monitoring signals S4 and S5 cause a failure (abnormality) in the output line control circuit 33. ) Or when the above-mentioned WDT signal or PSM signal is turned off.

  Instantaneous output drive signals S6 and S7 are respectively supplied from the first CPU 17 to the instantaneous output control units 38 and 39 of the instantaneous safety output circuit 31, and by these drive signals S6 and S7, a safe instantaneous output is provided. The logic of ON (safe side) / OFF (danger side) is controlled. That is, when the driving signals S6 and S7 are turned on and the above-described power supply line VL is turned on, the safety instantaneous outputs that are on the safe side are output from the instantaneous output terminals 42 and 43, respectively. To do.

  The instantaneous output control units 38 and 39 output monitor signals S9 and S10 to the first and second CPUs 17 and 18, respectively, and the instantaneous output control units 38 and 39 are normal. For example, the monitoring signals S9 and S10 are inverted logic signals of the driving signals S6 and S7.

  The off-delay output control units 40 and 41 of the off-delay safety output circuit 32 are supplied with off-delay output driving signals S12 and S13 from the second CPU 18, respectively. By the driving signals S12 and S13, The logic of the safety off-delay output on (safe side) / off (dangerous side) is controlled. That is, when the driving signals S12 and S13 are turned on and the above-described power supply line VL is turned on, an on-safety off-delay output which is a safe state is output from the off-delay output terminals 45 and 46. Output each.

  The off-delay output control units 40 and 41 output monitor signals S14 and S15 to the first and second CPUs 17 and 18, respectively. The off-delay output control units 40 and 41 are normal. If so, the monitoring signals S14 and S15 are inverted logic signals of the driving signals S12 and S13.

  The output line control circuit 33 for redundant safety output turns off the power supply line VL and outputs an instantaneous output terminal when a failure (abnormality) occurs in the instantaneous output control units 38, 39 or the off-delay output control units 40, 41. The safety outputs of 42 and 43 and off-delay output terminals 45 and 46 are all turned off to ensure safety.

  On the contrary, when a failure (abnormality) occurs in the output line control circuit 33, the instantaneous output terminals 42 and 43 and the off-delay output terminal are output by the instantaneous output control units 38 and 39 and the off-delay output control units 40 and 41, respectively. All safety outputs 45 and 46 are turned off to ensure safety.

  FIG. 8 is a block diagram of the single function unit 3, and parts corresponding to those in FIG.

  The single function unit 3 is not provided with the above-described AND input circuit 28, the off-delay safety output circuit 32, the setting switch 19, and the connector 37 for the extension unit. The same as 4.

  In this way, the control unit having the first and second CPUs 17 and 18 controls the safety output, which is a semiconductor output, in accordance with a program, so that the safety circuit is configured by a relay sequence as in a conventional relay unit incorporating an electromagnetic relay. There is no need to construct the system, and the number of wirings can be reduced. In addition, when the manufacturer wants to change a part of the system, it can easily cope with the change of the software.

  Next, the operation of each unit will be described based on some usage examples.

  FIG. 9 is a diagram showing a connection state when the high-function unit 4 is used alone, and FIG. 10 is a time chart thereof.

  In this example, for example, two contact points of one safety door switch are connected to the safety input 1 of the terminals T11 and T12 of the high-functional unit 4 and the safety input 2 of the terminals T21 and T22. The b contact of the magnet contactor is connected in series, and the reset button 50 is connected in series.

  The instantaneous output terminal S13 is connected to the amplifier 52, and the off-delay output terminals S43 and S53 are connected to the magnet contactors 48 and 49. In this example, a fixed time T is set as the off-delay time.

  As the door equipped with the safety door switch is closed, the two safety inputs 1 and 2 are turned on as shown in FIGS. 10 (a) and 10 (b), and as shown in FIG. 10 (c). When the reset input is turned off, on, and off, the safety instantaneous output of the terminal S13 is turned on as shown in FIG. 10D, and the terminals S43, S43, as shown in FIG. The safety off-delay output in S53 is turned on, the main contacts of the magnet contactors 48 and 49 are turned on, and the motor 51 is driven to operate the mechanical equipment.

  In this state, for example, when the door is opened, the two safety inputs 1 and 2 are turned off. The safety inputs 1 and 2 are turned on and off at the same time. FIG. 10B shows an example in which the safety input 2 is turned off with a delay.

  When either safety input 1 or 2 is turned off, the safety instantaneous output is turned off and slowed down by the amplifier 52 as shown in FIG. 10D, and the safety off-delay output is turned off after a certain time T. By doing so, the main contacts of the magnet contactors 48 and 49 are turned off, the power supply to the motor 51 is cut off, and the operation of the mechanical equipment is stopped.

  FIG. 11 is a diagram showing a state in which the instantaneous type extension unit 5 is connected to the high-function unit 4 and the number of output points is increased, and FIG. 12 is a time chart thereof.

  In this example, for example, two contacts of one safety door switch are connected to the safety input 1 of the terminals T11 and T12 of the high-function unit 4 and the safety input 2 of the terminals T21 and T22. The b contact of the magnet contactor is connected in series, and the reset button 50 is connected in series.

  The instantaneous output terminals S13 and S23 are connected to the magnet contactors 54 and 55, and the off-delay output terminals S33 and S43 are connected to the magnet contactors 56 and 57. In this example, T = 0 is set as the off-delay time, that is, it is an instantaneous output.

  The instantaneous output terminals 61 and 62 of the extension unit 5 incorporating two electromagnetic relays are connected to the magnet contactors 58 and 59.

  When the door equipped with the safety door switch is closed, as shown in FIGS. 12 (a) and 12 (b), the two safety inputs 1 and 2 of the high-function unit 4 are turned on. As shown in c), the reset input is turned off, on, and turned off, so that the safety instantaneous output of the high-function unit 4 is turned on as shown in FIG. As shown in FIG. 4, the safety instantaneous output of the extension unit 5 is turned on, whereby the magnetic contactors 54 to 59 are turned on and the motors 63 to 65 are driven to operate the mechanical equipment.

  In this state, for example, when the door is opened, the two safety inputs 1 and 2 are turned off as shown in FIGS. 12 (a) and 12 (b), and the high function unit as shown in FIG. 12 (c). 4 is turned off, and as shown in FIG. 12D, the safety instantaneous output of the extension unit 5 is turned off. As a result, each of the magnet contactors 54 to 59 is turned off and the motors 63 to 65 are turned off. The power supply is cut off and the operation of the mechanical equipment is stopped.

  Thus, by connecting the extension unit 5 to the high-function unit 4 via the cable 6, the number of safety output points can be easily increased.

  FIG. 13 is a diagram showing a connection state between the two high-function units 4-1 and 4-2 and the off-delay type extension unit 5, and FIG. 14 is a time chart thereof. The two safety inputs of the second high-functional unit 4-2 are referred to as safety inputs 3 and 4 for convenience.

  In this example, for example, two contacts of one safety door switch are connected to the safety input 1 of the terminals T11 and T12 and the safety input 2 of the terminals T21 and T22 of the first high-functional unit 4-1. The feedback loop 47 is connected in series with the b-contact of the magnet contactor and with the reset button 50 in series.

  The instantaneous output terminals S13 and S23 are connected to the magnet contactors 54 and 55, and the off-delay output terminals S33 and S43 are connected to the magnet contactors 56 and 57. In the first high function unit 4-1, T = 0 is set as the off delay time. The internal safety output terminal LO is connected to the internal safety input terminal LA of the second high function unit 4-2. That is, the internal safety output of the first high-function unit 4-1 is given as an AND input of the second high-function unit 4-2 at the subsequent stage.

  The safety input 3 of the terminals T11 and T12 of the second high-function unit 4-2 and the safety input 4 of the terminals T21 and T22 are different from, for example, the safety door switch of the first high-function unit 4-1 Two contacts of one safety door switch are connected, and the feedback loop 69 is connected in series with the b-contact of the magnetic contactor and in series with the reset button 70.

  The instantaneous output terminals S13 and S23 are connected to the magnet contactors 71 and 72, and the off-delay output terminals S43 and S53 are connected to the magnet contactors 73 and 74. In the second high function unit 4-2, a predetermined time T is set as an off-delay time.

  The off-delay output terminals 75 and 76 of the extension unit 5 incorporating a plurality of electromagnetic relays are connected to the magnet contactors 77 and 78.

  As shown in FIGS. 14A and 14B, the door of the safety door switch connected to the first high-function unit 4-1 is closed, and the two safety inputs 1 and 2 are turned on. As shown in FIG. 14C, the reset input is turned off, turned on, and turned off, so that the safety instantaneous output of the first high-function unit 4-1 is turned on. As shown, the main contacts of the magnetic contactors 54 to 57 of the first high-function unit 4-1 are turned on, and the motors 63 and 64 are driven. Further, the same internal safety output as the safety instantaneous output of the first high function unit 4-1 is given as the AND input of the second high function unit 4-2.

  The second high-function unit 4-2 is in a state where the internal safety input shown in FIG. 14F is turned on, and the safety output of the second high-function unit 4-2 is on the safe side. When the safety output is turned on. In FIG. 14, when the internal safety input is turned on, the door of the safety door switch connected to the second high function unit 4-2 is closed, as shown in FIGS. 14 (g) and 14 (h). In addition, since the two safety inputs 3 and 4 are on, as shown in FIG. 14 (i), when the reset input is turned off, on and off, the AND condition is established, and FIG. 14 (j) , (K), the safety instantaneous output and the safety off-delay output of the second high-function unit 4-2 are turned on, and the extension unit 5 is safety-off as shown in FIG. 14 (l). When the delay output is turned on, the magnet contactors 71 to 74, 77, 78 of the second high-function unit 4-2 and the extension unit 5 are turned on to drive the motors 79, 100, 101. It made.

  In this state, for example, when the door of the safety door switch connected to the first high function unit 4-1 is opened, as shown in FIGS. 14 (a) and 14 (b), the first high function The two safety inputs 1 and 2 of the unit 4-1 are turned off, and as shown in FIG. 14D, the safety instantaneous output of the first high-function unit 4-1 is turned off and the magnetic contactors 54 to 57 are turned on. The power supply to the motors 63 and 64 is cut off, and the internal safety output for the second high function unit 4-2 is also turned off as shown in FIG.

  The second high function unit 4-2 is shown in FIG. 14 (j) by turning off the internal safety input from the first high function unit 4-1 as shown in FIG. 14 (f). Thus, the safety instantaneous output is turned off and the magnet contactors 71 and 72 are turned off to cut off the power supply of the motor 79. Further, as shown in FIG. While the delay output is turned off, as shown in FIG. 14 (l), the safety off-delay output of the extension unit 5 is turned off. As a result, the contactors 73, 74, 77, 78 are turned off and the motors 100, 101 are turned off. The power supply to will be cut off.

  In this way, the safety output of the second high-function unit 4-2 can be easily associated with the safety output of the first high-function unit 4-1 by logical connection using the internal safety output.

  In this embodiment, as described above, the number of output points can be increased by connecting the extension unit 5 to the high function unit 4 via the cable 6. When the unit 5 is connected and the number of output points is increased, an abnormality such as welding of the relay contact of the extension unit 5 is detected as follows.

FIG. 15 is a schematic configuration diagram of a main part when a plurality of high function units 4, in this example, five extension units 5 _{1 to} 5 ₅ are connected via a cable 6. The two CPUs 17 and 18 of the functional unit 4 are representatively shown by one CPU. Although not shown in FIG. 15, a control signal corresponding to a safety output for controlling the two electromagnetic relays is sent from the high-functional unit 4 to the extension units 5 _{1 to} 5 ₅ via the cable 6. given through, by which, as described above, a relay output that opening and closing of the relay contacts in accordance with the output state of the safety output are controlled for each of the additional unit 5 _{1-5 5} of the electromagnetic relay, the contactor or the like (not shown) Output.

In this embodiment, the advanced unit 4, when via the cable 6 for connecting the plurality of expansion units 5 ₁ to 5 ₅ sequentially is in the expansion unit 5 ₅ connectors in the final stage, the terminating resistor 80 Thus, a feedback loop that returns from the high function unit 4 to the high function unit 4 via the plurality of extension units 5 _{1 to} 5 ₅ is configured.

In this feedback loop, a b contact 81 that is linked to an a contact that is an output contact of the two electromagnetic relays of the extension unit 4 shown in FIGS. 11 and 13 is connected in series. from example, the voltage of 24V is supplied, a feedback (FB) input is given to the detection circuit 82 provided in the high function unit 4 through the expansion unit 5 ₁ to 5 _5, the output of the detection circuit 82, is CPU17,18 been input such as welding of the output contacts of the expansion units ₅ 1 to 5 ₅ abnormality in the detection of the abnormality detection unit is performed.

  As shown in FIG. 16, the detection circuit 82 includes two first and second comparators 83 and 84, and the inverting input of the first comparator 83 and the non-inverting input of the second comparator 84 include A feedback input is commonly provided, and a first reference voltage VH and a second reference lower than the first reference voltage VH are applied to the non-inverting input of the first comparator 83 and the inverting input of the second comparator 84. A voltage VL is applied.

  The first and second reference voltages VH and VL are set as follows in a normal state where no abnormality has occurred.

That is, when the safety output is in the OFF state (dangerous), i.e., a contact for output expansion units 5 ₁ to 5 ₅ is off, b contact 81 interlocked with this a contact is turned on When the above feedback loop is formed, if the feedback input is FB,
VH>FB> VL
Next, also, when the safety output is ON (safety side), i.e., a contact of the relay output of the extension unit 5 _{1-5 5} is ON, b contact 81 interlocked with this a contact When OFF and the above feedback loop is not formed, VH>VL> FB
It becomes.

  In general, the output of the comparator is at a high level when the non-inverting input is larger than the inverting input, and is at the low level when the non-inverting input is smaller than the inverting input.

  Therefore, in a normal state, the outputs of the first and second comparators 83 and 84 are as shown in Table 1 below according to the output state of the safety output.

これに対して、異常が発生した場合、例えば、フィードバック入力がアースされて０Ｖになったような場合、フィードバック入力が出力と短絡して２４Ｖになったような場合、フィードバックループの途中で短絡してフィードバック入力が２４Ｖよりも低くなったような場合、および、出力用接点であるａ接点が溶着した場合においては、第１，第２のコンパレータ８３，８４の出力は、下記表２に示されるようになる。

On the other hand, when an abnormality occurs, for example, when the feedback input is grounded to 0V, or when the feedback input is short-circuited to the output to 24V, a short-circuit occurs in the middle of the feedback loop. When the feedback input becomes lower than 24V and when the contact a which is the output contact is welded, the outputs of the first and second comparators 83 and 84 are shown in Table 2 below. It becomes like this.

すなわち、フィードバック入力がアースされて０Ｖになったような場合には、電磁リレーの接点の開閉に拘わらず、第１のコンパレータ８３の出力は、ハイレベルに固定される一方、第２のコンパレータ８４の出力は、ローレベルに固定される。また、フィードバック入力が出力と短絡して２４Ｖになったような場合には、電磁リレーの接点の開閉に拘わらず、第１のコンパレータ８３の出力は、ローレベルに固定される一方、第２のコンパレータ８４の出力は、ハイレベルに固定される。また、フィードバックループの途中で短絡してフィードバック入力が２４Ｖよりも低くなったような場合には、電磁リレーの接点の開閉に拘わらず、第１のコンパレータ８３の出力は、ローレベルに固定される一方、第２のコンパレータ８４の出力は、ハイレベルに固定される。

That is, when the feedback input is grounded and becomes 0V, the output of the first comparator 83 is fixed at the high level regardless of the opening / closing of the contact of the electromagnetic relay, while the second comparator 84 The output of is fixed at a low level. Further, when the feedback input is short-circuited with the output and becomes 24V, the output of the first comparator 83 is fixed at the low level regardless of the opening / closing of the contact of the electromagnetic relay, while the second The output of the comparator 84 is fixed at a high level. Further, when the feedback input becomes lower than 24 V due to a short circuit in the middle of the feedback loop, the output of the first comparator 83 is fixed at a low level regardless of the opening / closing of the contact of the electromagnetic relay. On the other hand, the output of the second comparator 84 is fixed at a high level.

  Further, when the contact a which is the output contact is welded, the contact b linked to the contact a remains off, and the contact b remains off even when the safety output is turned off. The output remains low.

  Therefore, the CPUs 17 and 18 detect an abnormality as follows based on the outputs of the first and second comparators 83 and 84.

  That is, as apparent from Tables 1 and 2 above, when the outputs of the first and second comparators 83 and 84 are both high in the state where the safety output is off, it is normal. When it is not normal, the outputs of the first and second comparators 83 and 84 are not at a high level.

  Therefore, when the safety output is switched from the off state to the on state, it is determined whether both the outputs of the first and second comparators 83 and 84 are in a high level normal state. Sometimes, the safety output is switched on, and when it is not normal, appropriate processing is performed such as displaying the occurrence of abnormality without switching the safety output.

  FIG. 17 is a flowchart showing the processing operation of this abnormality detection.

First, it is determined whether or not the safety output is switched from the off state to the on state (step n1). When the switching is not performed, the process ends. When the switching is switched, it is determined whether or not the output of the first comparator 83 is at a high level. Judgment is made (step n2), and when it is not at high level, an error is displayed and the process is terminated (step n5).
In step n2, when the output of the first comparator 83 is at a high level, it is determined whether or not the output of the second comparator 84 is at a high level (step n3). If it occurs, the process ends with an error display or the like (step n5). When the level is high, the safety output is assumed to be normal, and the safety output is switched from the off state to the on state (step n4).

  Note that the abnormality when the output of the first comparator 83 is not at the high level in step n2 corresponds to a short-circuit of the feedback loop or the like as shown in Table 2 above. In step n3, the second comparator 84 Abnormality when the output of is not at a high level corresponds to welding of the contacts.

  In this way, it is possible to detect abnormalities such as welding of relay contacts of the electromagnetic relay of the extension unit 5 and short-circuiting or disconnection of the feedback loop configured via the extension unit 5, so when an abnormality occurs, the safety output is turned on. In other words, it is possible to avoid switching to the safety side that permits the operation of the mechanical equipment, and safety can be ensured.

(Other embodiments)
In the above-described embodiment, the logical connection is performed by AND. However, the logical connection is not limited to AND, and may be logical connection by OR, XOR, or the like, and a plurality of logical connections may be possible.

  In the above-described embodiment, the extension unit 5 connected to the final stage is equipped with a termination connector. However, as another embodiment of the present invention, an extension unit dedicated to the final stage including a termination resistor is prepared. The extension unit may be connected to the final stage. Alternatively, a termination resistor may be built in each extension unit, and when used as the final stage, the termination resistor may be connected to the feedback loop by operation.

  In the above-described embodiment, the high-function unit 4 and the extension unit 5 or the extension units 5 are connected via a cable. However, as another embodiment of the present invention, the connectors of the units can be directly connected to each other. It is good.

  Of course, the number of safety outputs and internal safety outputs (internal safety inputs) of the single-function unit 3 and the high-function unit 4 is not limited to the above-described embodiment.

  The present invention is useful for building a safety system.

It is a figure which shows the structural example of the system which concerns on one embodiment of this invention. It is a front view of the single function unit of FIG. It is a front view of the high-functional unit of FIG. It is a rear view of the high-functional unit of FIG. It is a front view of the extension unit of FIG. It is a block diagram of the high-functional unit of FIG. It is a block diagram which shows the detail of a part of FIG. It is a block diagram of the single function unit of FIG. It is a figure which shows the connection state of the 1st usage example. It is a time chart of FIG. It is a figure which shows the connection state of the 2nd usage example. It is a time chart of FIG. It is a figure which shows the connection state of the 3rd usage example. It is a time chart of FIG. It is a figure which shows the structure of the feedback loop of an expansion unit. FIG. 16 is a block diagram of the detection circuit of FIG. 15. It is a flowchart with which operation | movement description is provided.

Explanation of symbols

1 Safety Door Switch 2 Emergency Stop Switch 3 Single Function Unit 4 High Function Unit 5 Extension Unit 6 Cable 17, 18 First and Second CPU
31 Safety output circuit for moment 32 Safety output circuit for off-delay 34 Internal safety output circuit 80 Termination resistor 82 Detection circuit

Claims (3)

A safety controller that controls the operation of mechanical equipment by giving a safety output to a safety output control target based on an input from an input device,
A safety output unit for providing a semiconductor output as the safety output;
A control unit for controlling the safety output according to a program based on the input from the input device ;
An abnormality detection unit for detecting an abnormality,
A plurality of extension units with built-in electromagnetic relays that output the relay output corresponding to the safety output to the safety output control target can be sequentially connected to the safety controller via the extension unit,
The abnormality detection unit detects an abnormality based on a feedback input of a feedback loop that returns from the safety controller configured by connecting the extension unit to the safety controller via the extension unit. . 2. The safety controller according to claim 1, wherein a termination resistor is attached to a final-stage expansion unit among the plurality of expansion units connected in sequence, and the feedback loop is configured through the termination resistor . The electromagnetic relay has an a contact and a b contact interlocking with each other, and one of the two contacts is an output contact for outputting the relay output, and the other contact is in the feedback loop. Concatenated,
The safety controller according to claim 1 or 2, wherein the abnormality detection unit detects at least one of welding of the output contact of the electromagnetic relay and abnormality of the feedback loop.

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