Analog current output system

Abstract

The embodiment of the present disclosure relates to an analog current output system, which includes a first current output module, the current working state of the first current output module is configured as a working mode and outputs current to a load, and the first current output module also generates a first self-test signal about the current working state; and a second current output module, the current working state of the second current output module is in a standby mode; and a redundant switching module, which is configured to switch the second current output module to a working mode in response to the first self-test signal being converted from a state representing a normal self-test to a state representing a self-test failure, switch the first current output module to a standby mode, and maintain the current working state in response to the self-test signal representing a self-test failure within a predetermined time after the second current output module is switched to the working mode. The system can ensure the stability of redundant switching and avoid redundant switching confusion.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of industrial control, and more particularly to an analog current output system. Background Art

[0002] Analog current output systems are often used in industrial control situations. In order to improve reliability, two devices are often used in a redundant manner. Redundant switching generally follows the principle of "whoever is healthy works", so it is necessary to obtain the health status of the working and standby modules in real time, and the standby module is also required to perform complete output circuit diagnosis. The current output system has high power consumption. If the standby module also has a complete output circuit (the current flows inside the module, not the load), then a large amount of power consumption is consumed inside the module, resulting in severe heating and affecting reliability. At the same time, it is difficult to effectively distinguish between internal and external faults of the output module, resulting in confusion in redundant switching. Summary of the invention

[0003] In view of the above problems, the present disclosure provides an analog current output system, which can ensure the stability of redundant switching and avoid redundant switching confusion.

[0004] According to one aspect of the present disclosure, an analog current output system is provided. The analog current output system includes: a first current output module, the current working state of the first current output module is configured as a working mode and outputs current to a load, and the first current output module also generates a first self-test signal about the current working state; and a second current output module, the current working state of the second current output module is in a standby mode; and a redundant switching module is configured to switch the second current output module to a working mode and the first current output module to a standby mode in response to the first self-test signal being converted from a state representing a normal self-test to a state representing a self-test failure, and maintain the working states of the first current output module and the second current output module in response to the self-test signal representing a self-test failure within a predetermined time after the second current output module is switched to the working mode.

[0005] In some embodiments, the redundant switching module is configured to enable the first current output module and the second current output module to be in one of a working mode and a standby mode mutually exclusively.

[0006] In some embodiments, the redundant switching module includes: a first redundant switching unit, configured to generate a first redundant control signal representing the right to give way when the first self-test signal is converted from a state representing a normal self-test to a state representing a self-test failure, so as to switch the working states of the first current output module and the second current output module.

[0007] In some embodiments, the first current output module also includes: a first power selection unit, electrically connected to the first current source, the first power selection unit is configured to output a first voltage to the first current source in response to a first redundant control signal characterizing a right to give way, and to output a second voltage to the first current source in response to a first redundant control signal characterizing a right not to give way, the first voltage being less than the second voltage; and the first current source, the current output end of the first current source being electrically connected to the load.

[0008] In some embodiments, the first current output module further includes: a first redundant control unit electrically connected to the output end of the first current source and the load, and configured to output the current output by the first current source to the load in response to a first redundant control signal indicating non-yielding.

[0009] In some embodiments, the first redundant control unit includes: a first resistor, one end of the first resistor is configured to receive a first redundant control signal, and the other end of the first resistor is electrically connected to the control end of the first switch unit; a first switch unit, a first end of the first switch unit is electrically connected to the current output end of the first current source, and a second end of the first switch unit is grounded; and a first diode, a positive electrode of the first diode is electrically connected to the current output end of the first current source, and a negative electrode of the first diode is electrically connected to the load.

[0010] In some embodiments, the first switch unit includes a first MOS tube, the gate of the first MOS tube serves as the control end of the first switch unit, the drain of the first MOS tube serves as the first end of the first switch unit, the source of the first MOS tube serves as the second end of the first switch unit, and the drain-source voltage of the first MOS tube when it is turned on is less than the conduction voltage drop of the first diode.

[0011] In some embodiments, the first switch unit includes a first transistor, the base of the first transistor serves as the control end of the first switch unit, the collector of the first transistor serves as the first end of the first switch unit, and the emitter of the first transistor serves as the second end of the first switch unit. The first transistor is in a saturation state when turned on, so that the conduction voltage drop of the first transistor is less than the conduction voltage drop of the first diode.

[0012] In some embodiments, the first current output module also includes: a first self-test unit, electrically connected to the current output end of the first current source, configured to detect whether the current output by the first current source meets predetermined conditions, generate a self-test signal indicating that self-test is normal in response to determining that the current output by the first current source meets the predetermined conditions, and generate a self-test signal indicating that self-test is faulty in response to determining that the current output by the first current source does not meet the predetermined conditions.

[0013] In some embodiments, the first current output module further includes: a first control unit configured to generate a switching instruction; and the first redundant switching unit is further configured to generate a first redundant control signal representing the right to yield according to the switching instruction.

[0014] In some embodiments, the redundant switching module is further configured to switch the working states of the first current output module and the second current output module in response to the reset signal being converted from an invalid state to a valid state.

[0015] According to the analog current output system disclosed in the present invention, the first current output module in the working mode also generates a first self-test signal about the current working state, the current working state of the second current output module is in the standby mode and outputs a second self-test signal about the current working state and a third self-test signal about the previous working state, and the working states of the first current output module and the second current output module are switched based on the first self-test signal, the second self-test signal and the third self-test signal, which can effectively avoid redundant switching confusion.

[0016] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements.

[0018] Figure 1 A block diagram of an analog current output system according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0019] The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0020] The term "including" and its variations used in this document represent open inclusion, that is, "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same objects. The terms "connected" and "electrically connected" may refer to a direct connection or an indirect connection via other units or modules. Other explicit and implicit definitions may also be included below.

[0021] As described above, when the analog current output system is redundantly configured, the general logic is that the constant current source of the working module drives the load, and the standby module is in hot standby state and does not drive the load.

[0022] The analog current output system usually uses a 24V (volt) drive power supply. The on-site load is generally several hundred ohms. The power consumption inside the module is (24V-I*R)*I, where I represents the drive current, that is, the current output by the constant current source. The size of I is, for example, 4~20mA (milliamperes), and R represents the load resistance. In the case of redundant configuration, it is necessary to switch to the backup module when the working module fails. For the constant current source output, there is no output loop, and it is impossible to effectively diagnose whether the constant current source is normal. Therefore, some analog current output systems have the problem of blind switching. More often, an internal current loop is provided for the backup module for self-diagnosis of the backup module, and the current of the backup module does not flow through the load and is consumed inside the backup module, causing the temperature of the backup module to rise, affecting reliability.

[0023] Based on this, in order to solve this problem, the most commonly used method is to use a variable drive power supply design for the constant current source, that is, to adjust the drive power supply size in real time according to the load size. When used as a backup module, the load is small and the drive power supply is also small. This solution has a good power consumption reduction effect, but in industrial control situations, there are a large number of analog current output systems. A module usually has 8 or even 16 constant current sources. Adding a DC-DC (DC-DC converter) to each constant current source is expensive and affects the module's volume ratio. Another method is that the standby card adopts an intermittent current loop opening solution. This solution can also reduce heat generation, but during the intermittent opening process, there is a transient overshoot signal, and frequent operation can easily cause module damage.

[0024] When the redundant modules are overloaded or not connected to the load, some of them may work while others may fail. If there is no good switching mechanism, it will lead to redundant switching confusion.

[0025] Therefore, the prior art has the following disadvantages:

[0026] (1) When using a conventional analog current output redundancy system, the constant current source of the working module works, while the constant current source of the standby module does not work. The standby module cannot effectively self-diagnose, resulting in uncertainty about whether the standby module is healthy when the working module is switched to redundancy. At the same time, the constant current source of the standby module has a long response process from not working to effective output, which can easily cause switching disturbances;

[0027] (2) Currently, many analog current output redundant systems solve the problem described in (1), that is, the constant current source of the standby module forms a loop inside the module, which solves the self-diagnosis problem. However, the power consumption is completely reduced inside the module, resulting in excessive power consumption inside the standby module, which is much higher than that of the working module, affecting system reliability.

[0028] (3) Based on (2), some systems use an adaptive constant current source, that is, each constant current source is equipped with an adaptive DC-DC circuit, and the DC-DC output is dynamically adjusted according to the load size. This solution can effectively solve the problem of (2), but for multi-channel analog current output systems, the module is complex and expensive, which affects the module volume ratio;

[0029] (4) Based on (2), some systems’ backup modules use the method of intermittently turning on the backup card constant current source for self-diagnosis. However, there is inevitably a transient overshoot signal when the constant current source is turned on. Frequent operation can easily damage the module. In addition, at the moment of redundant switching, there is also a process in which the constant current source outputs from zero to one, and the response cycle is relatively long.

[0030] (5) When the redundant modules are overloaded, some modules may work while others may fail, which may cause problems with switching back and forth or the inability to switch effectively when the load is disconnected (a channel that is not in use may also appear as disconnected, but this is normal).

[0031] In order to at least partially solve the above-mentioned problems and one or more of other potential problems, an example embodiment of the present disclosure proposes an analog current output system, wherein a first current output module in working mode also generates a first self-test signal about the current working state, and the current working state of the second current output module is in standby mode and outputs a second self-test signal about the current working state and a third self-test signal about the previous working state. Based on the first self-test signal, the second self-test signal and the third self-test signal, the working states of the first current output module and the second current output module are switched, which can effectively avoid redundant switching confusion.

[0032] The embodiment of the present disclosure is an analog current output system 100, which includes two current output modules, which are mutually exclusive configured as one of a working mode and a standby mode, and the current output module configured as the working mode outputs current to a load. The current output module configured as the working mode is configured to generate a corresponding redundant control signal according to a first self-test signal of the current output module configured as the working mode, a second self-test signal of the current output module configured as the standby mode, and a third self-test signal of the current output module configured as the standby mode before being configured as the standby mode, wherein the redundant control signal representing the right to yield is used to configure the current output module configured as the standby mode into the working mode.

[0033] For example, the analog current output system 100 includes a first current output module 101, a second current output module 102 and a redundant switching module 103. The first current output module 101 can be any one of the two current output modules, and the second current output module 102 is the other of the two current output modules. The redundant switching module 103 is configured to make the first current output module 101 and the second current output module 102 mutually exclusive in one of the working mode and the standby mode. The redundant switching module 103 can, for example, generate a corresponding redundant control signal so that the working state of the first current output module 101 is the working mode so as to output current to the load RL, and the working state of the second current output module 102 is the standby mode, that is, the second current output module 102 does not output current to the load RL. It should be understood that the redundant switching module 103 can, for example, generate a corresponding redundant control signal so that the working states of the first current output module 101 and the second current output module 102 are switched to each other.

[0034] Among them, the current working state of the first current output module 101 is configured as a working mode and outputs current to the load RL, and the first current output module 101 also outputs a first self-test signal about the current working state. The current working state of the second current output module 102 is in a standby mode. In some embodiments, the current output end of the second current output module 102 is connected to the load RL, but the second current output module 102 in the standby mode does not output current to the load RL.

[0035] The redundant switching module 103 is configured to switch the second current output module 102 to the working mode and the first current output module 101 to the standby mode in response to the first self-test signal being converted from a state representing a normal self-test to a state representing a self-test failure, and to maintain the switched working states of the first current output module 101 and the second current output module 102 in response to the self-test signal representing a self-test failure within a predetermined time after the second current output module 102 is switched to the working mode. The self-test of the first current output module 101 can be completed by the first self-test unit. The first self-test unit can periodically perform self-test on the first current output module 101 at a predetermined frequency. The first self-test unit can also perform self-test on the first current output module 101 in response to the self-test instruction of the first control unit. The self-test of the second current output module 102 can be completed by the second self-test unit.

[0036] That is, taking the current working state of the first current output module 101 in the initial state as the working mode and the current working state of the second current output module 102 as the standby mode as an example, if the first self-test signal of the first current output module 101 in the working mode indicates that the self-test is normal, the redundant switching module 103 maintains the working states of the first current output module 101 and the second current output module 102 without switching. If the first self-test signal of the first current output module 101 in the working mode is converted from a state indicating that the self-test is normal to a state indicating that the self-test is faulty, it indicates that the first current output module 101 involves a related self-test fault during the working process, so the redundant switching module 103 performs a redundant switching operation, so that the second current output module 102 is switched to the working mode, and the first current output module 101 is switched to the standby mode.

[0037] After the working state switching is completed, if the self-test signal within the predetermined time after the second current output module 102 is switched to the working mode indicates that the self-test is normal, the redundant switching module 103 can determine that the self-test failure of the first current output module 101 is a failure of the first current output module 101 itself, and maintain the switched working states of the first current output module 101 and the second current output module 102, so that the second current output module 102 maintains the working mode and the first current output module 101 maintains the standby mode. The above-mentioned "predetermined time" can be related to the periodicity of the self-test unit periodically performing self-tests at a predetermined frequency, and can also be reasonably set according to actual conditions. The self-test implemented within the predetermined time is usually the first self-test performed on the current output module after the working state switching is completed.

[0038] After the working state switching is completed, if the self-test signal within a predetermined time after the second current output module 102 is switched to the working mode indicates a self-test fault, the redundancy switching module 103 can determine that the self-test fault of the first current output module 101 and the self-test fault of the second current output module 102 are not the faults of the first current output module 101 and the second current output module 102 themselves, but belong to a "common fault". A "common fault" is, for example, a fault caused by external reasons, which will cause the self-test signals of the first current output module 101 and the second current output module 102 to present a state indicating a self-test fault when there is no fault in the first current output module 101 and the second current output module 102 themselves. At this time, the first current output module 101 and the second current output module 102 maintain the switched working states of the first current output module 101 and the second current output module 102, so that the second current output module 102 maintains the working mode and the first current output module 101 maintains the standby mode, and no working state switching is performed, thereby effectively avoiding the problem that the self-test signals for the first current output module 101 and the second current output module 102 are always in a state representing a self-test fault due to an external common fault, resulting in the working states of the first current output module 101 and the second current output module 102 being switched back and forth frequently and unnecessarily.

[0039] The above self-detection fault includes, for example, a load RL disconnection fault.

[0040] For example, the analog current output system 100 includes a first current output module 101 and a second current output module 102. The first current output module 101 and the second current output module 102 are mutually exclusive configured as one of a working mode and a standby mode. For example, when the first current output module 101 is configured as a working mode, the first current output module 101 outputs current to the load RL; at this time, the second current output module 102 is configured as a standby mode, and at this time, the second current output module 102 does not output current to the load RL. Alternatively, when the second current output module 102 is configured as a working mode, the second current output module 102 outputs current to the load RL; at this time, the first current output module 101 is configured as a standby mode, and at this time, the first current output module 101 does not output current to the load RL. That is, at the same time, only one of the first current output module 101 and the second current output module 102 is configured as a working mode to output current to the load RL.

[0041] In some embodiments, the redundant switching module 103 includes a first redundant switching unit 111 and a second redundant switching unit 121. Based on the interaction between the first redundant switching unit 111 and the second redundant switching unit 121, the first current output module 101 and the second current output module 102 can be mutually exclusively configured as one of the working mode and the standby mode. The first redundant switching unit 111 is configured to generate a first redundant control signal WORK1 representing the right to give up when the first self-test signal is converted from a state representing a normal self-test to a state representing a self-test failure, so as to switch the working state of the first current output module 101 and the second current output module 102. The first redundant control signal WORK1 output by the first redundant switching unit 111 is transmitted to the first current output module 101 and the second redundant switching unit 121. The first redundant control signal WORK1 representing the right to give up causes the working state of the first current output module 101 to switch to the standby state. The second redundant switching unit 121 generates a second redundant control signal WORK2 representing the right not to give up according to the first redundant control signal WORK1 representing the right to give up received from the first redundant switching unit 111. The second redundant control signal WORK2 output by the second redundant switching unit 121 is transmitted to the second current output module 102 and the first redundant switching unit 111. The second redundant control signal WORK2 indicating not yielding the right causes the working state of the second current output module 102 to switch to the working mode. The first redundant switching unit 111 maintains the output of the first redundant control signal WORK1 indicating yielding the right according to the second redundant control signal WORK2 indicating not yielding the right, so that the working states of the first current output module 101 and the second current output module 102 are mutually exclusive.

[0042] The first current output module 101 further includes a first power supply selection unit 112 and a first current source 113. In some embodiments, the first current output module 101 further includes a first redundant control unit 114, a first self-checking unit (not shown), a first control unit 116, and a first digital-to-analog conversion unit 117.

[0043] The first power selection unit 112 is electrically connected to the first current source 113. The first power selection unit 112 is configured to output a first voltage (e.g., VCC_LOW1) to the first current source 113 in response to a first redundant control signal indicating a right to give up, and to output a second voltage (e.g., VCC_HIGH1) to the first current source 113 in response to a first redundant control signal WORK1 indicating a right not to give up, wherein the first voltage is less than the second voltage. The current output terminal of the first current source 113 is electrically connected to the load RL. The first voltage is, for example, 5V, and the second voltage is, for example, 24V.

[0044] When the first current output module 101 is in working mode, the first current source 113 needs to drive the load RL (i.e., output current to the load RL), so the first current source 113 needs a relatively high driving power supply, such as a 24V power supply. When the first current output module 101 is in standby mode, the first current source 113 does not need to drive the load, and can only form a loop inside the module. Therefore, the first current source 113 only needs a lower voltage (such as 5V). Therefore, using the first power selection unit 112, a higher working voltage can be configured for the first current source 113 in working mode, and a lower working voltage can be configured when the first current source 113 is in standby mode, so as to effectively reduce power consumption and solve the problem of self-diagnosis of the output loop of the current output module in standby mode and high power consumption of the standby module.

[0045] Taking the second voltage as 24V and the first voltage as 5V as an example, compared with the case where the power selection unit is not provided (i.e., the first current source uses the same driving voltage in the working mode and the standby mode), in the standby mode, the power consumption of the first current source is reduced to about 20% of the power consumption in the case where the power selection unit is not provided. In addition, in some embodiments, the power selection unit can multiplex multiple current source channels.

[0046] It is worth noting that, in some embodiments, the first redundant control signal WORK1 output by the first redundant switching unit 111 is directly electrically connected to the control terminal of the first power selection unit 112 , so the switching speed is fast.

[0047] The first redundant control unit 114 is electrically connected to the output terminal of the first current source 113 and the load RL. The first redundant control unit 114 is configured to output the current output by the first current source 113 to the load RL in response to the first redundant control signal indicating non-yield.

[0048] In some embodiments, the first redundant control unit 114 includes a first resistor R1, a first switch unit 115, and a first diode D1. One end of the first resistor R1 is configured to receive a first redundant control signal, and the other end of the first resistor R1 is electrically connected to a control end of the first switch unit 115. A first end of the first switch unit 115 is electrically connected to a current output end of the first current source 113, and a second end of the first switch unit 115 is grounded (GND). An anode of the first diode D1 is electrically connected to a current output end of the first current source 113, and a cathode of the first diode D1 is electrically connected to a load RL. With respect to the first switch unit 115, for example, by controlling a signal at a control end of the first switch unit 115, the first end and the second end of the first switch unit 115 can be turned on, or the first end and the second end of the first switch unit 115 can be turned off.

[0049] When the first redundant control signal WORK1 output by the first redundant switching unit 111 indicates not giving up power (for example, the first redundant control signal WORK1 is at a low level), the first switch unit 115 is in an off state, and the current output by the first current source 113 is output to the load RL via the first diode D1. When the first redundant control signal WORK1 output by the first redundant switching unit 111 indicates giving up power (for example, the first redundant control signal WORK1 is at a high level), the first switch unit 115 is in an on state, and the current output by the first current source 113 forms a current loop via the first switch unit 115.

[0050] In some embodiments, the first switch unit 115 includes a first MOS transistor, the gate of the first MOS transistor serves as the control terminal of the first switch unit 115, the drain of the first MOS transistor serves as the first terminal of the first switch unit 115, the source of the first MOS transistor serves as the second terminal of the first switch unit, and the drain-source voltage of the first MOS transistor when it is turned on is less than the conduction voltage drop of the first diode. In some embodiments, the drain-source voltage of the first MOS transistor when it is turned on is less than 1 / 2 of the conduction voltage drop of the first diode. When the first redundant control signal WORK1 output by the first redundant switching unit 111 indicates the right to give, the first MOS transistor is turned on, and the current output by the first current source 113 forms a current loop through the first MOS transistor. Since the drain-source voltage of the first MOS transistor when it is turned on is less than the conduction voltage drop of the first diode, the first current source 113 can be prevented from generating leakage current flowing through the load RL.

[0051] In some embodiments, the first switch unit 115 includes a first transistor, the base of the first transistor serves as the control terminal of the first switch unit 115, the collector of the first transistor serves as the first terminal of the first switch unit 115, and the emitter of the first transistor serves as the second terminal of the first switch unit 115. The first transistor is in a saturated state when it is turned on, so that the conduction voltage drop of the first transistor is less than the conduction voltage drop of the first diode D1. It should be understood that for the case where the current output by the first current source 113 ranges from 4 to 20 mA, the saturation conduction voltage drop of the transistor is generally 0.1 to 0.3 V, which is much less than the conduction voltage drop of the diode. Therefore, when the first transistor is in a saturated conduction state, the first current source 113 will not generate leakage current flowing through the load RL.

[0052] It is worth noting that, in some embodiments, the first redundant control signal WORK1 output by the first redundant switching unit 111 is directly electrically connected to the control terminal of the first redundant control unit 114 , which can increase the switching speed.

[0053] The first self-test unit is electrically connected to the current output end of the first current source 113, and is configured to detect whether the current output by the first current source 113 meets a predetermined condition, generate a self-test signal indicating that the self-test is normal in response to determining that the current output by the first current source 113 meets the predetermined condition, and generate a self-test signal indicating that the self-test is faulty in response to determining that the current output by the first current source does not meet the predetermined condition.

[0054] For example, the first control unit 116 sends a control signal (the control signal is a digital signal) for controlling the output current of the first current source 113 to the first digital-to-analog conversion unit 117. The first digital-to-analog conversion unit 117 converts the control signal into an analog signal so as to control the output current of the first current source 113. Through the control of the first control unit 116, the output current of the first current source 113 can be a target value between 4 and 20 mA. When the first current output module 101 is in the working mode, the first self-test unit detects the magnitude of the current output by the first current output module 101. If the magnitude of the current output by the first current output module 101 is within a reasonable range with respect to the target value, it means that the current output by the first current source meets the predetermined condition, and the first self-test unit outputs a self-test signal indicating that the self-test is normal; if the magnitude of the current output by the first current output module 101 deviates from the reasonable range with respect to the target value (for example, the magnitude of the current output by the first current output module 101 is less than 50% of the target value), it means that the current output by the first current source does not meet the predetermined condition, and the first self-test unit outputs a self-test signal indicating that the self-test is normal. The first self-test unit is, for example, also electrically connected to the first control unit 116 so as to transmit the self-test signal to the first control unit 116, and the first control unit 116 can store the self-test signal. The first control unit 116 can be implemented by, for example, an MCU (microprocessing unit), a CPU (central processing unit), an FPGA (field programmable gate array), etc.

[0055] When the first current output module 101 is in the working mode, the first self-test unit generates a first self-test signal about the current working state, and the first control unit 116 stores the first self-test signal. The first self-test unit, for example, periodically performs self-test on the first current output module 101 at a predetermined frequency, or performs self-test on the first current output module 101 in response to a self-test instruction of the first control unit. When the first self-test signal is converted from a state representing a normal self-test to a state representing a self-test failure, it indicates that the first current output module 101 involves a related self-test failure, so the redundant switching module 103 performs a redundant switching operation, so that the second current output module 102 is switched to the working mode, and the first current output module 101 is switched to the standby mode.

[0056] When the first current output module 101 is in the standby mode, the first self-test unit still detects the magnitude of the current output by the first current output module 101, so as to determine whether the magnitude of the current output by the first current output module 101 meets the predetermined condition, and generates a corresponding self-test signal. The self-test signal of the first current output module 101 can be output to the second redundant switching unit 121, for example (see the arrow indicating the input signal of the second redundant switching unit 121). Similarly, the self-test signal of the second current output module 102 can be output to the first redundant switching unit 111, for example (see the arrow indicating the input signal of the first redundant switching unit 111).

[0057] The first redundant switching unit 111 may be implemented based on a combinational logic circuit or a sequential logic circuit. The input signal received by the first redundant switching unit 111 may include, for example, a reset signal, a switching control signal from the first control unit 116, a first self-test signal from the first self-test unit, a self-test signal from the second current output module 102, and a second redundant control signal WORK2 from the second current output module 102. The first redundant switching unit 111 generates a first redundant control signal WORK1 according to the above input signals.

[0058] The second current output module 102 further includes a second power supply selection unit 122 and a second current source 123. In some embodiments, the second current output module 102 further includes a second redundant control unit 124, a second self-test unit (not shown), a second control unit 126, and a second digital-to-analog conversion unit 127.

[0059] The second power selection unit 122 is electrically connected to the second current source 123. The second power selection unit 122 is configured to output a first voltage (e.g., VCC_LOW2) to the second current source 123 in response to a second redundant control signal indicating a right to give up, and to output a second voltage (VCC_HIGH2) to the second current source 123 in response to a second redundant control signal indicating a right not to give up, wherein the first voltage is less than the second voltage. The current output terminal of the second current source 123 is electrically connected to the load RL.

[0060] The second redundant control unit 124 is electrically connected to the output terminal of the second current source 123 and the load RL. The second redundant control unit 124 is configured to output the current output by the second current source 123 to the load RL in response to the second redundant control signal indicating non-yield.

[0061] In some embodiments, the second redundant control unit 124 includes a second resistor R2, a second switch unit 125, and a second diode D2. One end of the second resistor R2 is configured to receive a second redundant control signal WORK2, and the other end of the second resistor R2 is electrically connected to the control end of the second switch unit 125. The first end of the second switch unit 125 is electrically connected to the current output end of the second current source 123, and the second end of the second switch unit 125 is grounded (GND). The anode of the second diode D2 is electrically connected to the current output end of the second current source 123, and the cathode of the second diode D2 is electrically connected to the load RL. With respect to the second switch unit 125, for example, the control of the signal at the control end of the second switch unit 125 can make the first end and the second end of the second switch unit 125 conductive, or make the first end and the second end of the second switch unit 125 disconnected.

[0062] When the second redundant control signal WORK2 output by the second redundant switching unit 121 indicates not giving up power (for example, the second redundant control signal WORK2 is at a low level), the second switch unit 125 is in an off state, and the current output by the second current source 123 is output to the load RL via the second diode D2. When the second redundant control signal WORK2 output by the second redundant switching unit 121 indicates giving up power (for example, the second redundant control signal WORK2 is at a high level), the second switch unit 125 is in an on state, and the current output by the second current source 123 forms a current loop via the second switch unit 125.

[0063] In some embodiments, the second switch unit 125 includes a second MOS transistor, the gate of the second MOS transistor serves as the control end of the second switch unit 125, the drain of the second MOS transistor serves as the first end of the second switch unit 125, the source of the second MOS transistor serves as the second end of the second switch unit 125, and the drain-source voltage of the second MOS transistor when it is turned on is less than the conduction voltage drop of the second diode D2. In some embodiments, the drain-source voltage of the second MOS transistor when it is turned on is less than 1 / 2 of the conduction voltage drop of the second diode. When the second redundant control signal WORK2 output by the second redundant switching unit 121 indicates the right to give, the second MOS transistor is turned on, and the current output by the second current source 123 forms a current loop through the second MOS transistor. Since the drain-source voltage of the second MOS transistor when it is turned on is less than the conduction voltage drop of the second diode, the second current source 123 can be prevented from generating leakage current flowing through the load RL.

[0064] In some embodiments, the second switch unit 125 includes a second triode, the base of the second triode serves as the control terminal of the second switch unit 125, the collector of the second triode serves as the first terminal of the second switch unit 125, and the emitter of the second triode serves as the second terminal of the second switch unit 125. When the second triode is turned on, it is in a saturated state, so that the conduction voltage drop of the second triode is less than the conduction voltage drop of the second diode D2. It should be understood that for the case where the current output by the second current source 123 ranges from 4 to 20 mA, the saturated conduction voltage drop of the triode is generally 0.1 to 0.3 V, which is much less than the conduction voltage drop of the diode. Therefore, when the second triode is in a saturated conduction state, the second current source 123 will not generate leakage current flowing through the load RL.

[0065] It should be noted that the second redundancy control signal WORK2 outputted by the second redundancy switching unit 121 is directly electrically connected to the control terminal of the second redundancy control unit 124 .

[0066] The second self-test unit is electrically connected to the current output end of the second current source 123, and is configured to detect whether the current output by the second current source 123 meets a predetermined condition, generate a self-test signal indicating that the self-test is normal in response to determining that the current output by the second current source 123 meets the predetermined condition, and generate a self-test signal indicating that the self-test is faulty in response to determining that the current output by the second current source 123 does not meet the predetermined condition.

[0067] For example, the second control unit 126 sends a control signal (the control signal is a digital signal) for controlling the output current of the second current source 123 to the second digital-to-analog conversion unit 127. The second digital-to-analog conversion unit 127 converts the control signal into an analog signal so as to control the output current of the second current source 123. Through the control of the second control unit 126, the output current of the second current source 123 can be set to a target value between 4 and 20 mA (for example, the target value is 10 mA). When the second current output module 102 is in the working mode, the second self-check unit detects the current output by the second current output module 102. If the magnitude of the current output by the second current output module 102 is within a reasonable range with respect to the target value, it means that the current output by the second current source meets the predetermined condition, and the second self-test unit outputs a self-test signal indicating that the self-test is normal; if the magnitude of the current output by the second current output module 102 deviates from the reasonable range with respect to the target value (for example, the magnitude of the current output by the second current output module 102 is less than 50% of the target value), it means that the current output by the second current source does not meet the predetermined condition, and the second self-test unit outputs a self-test signal indicating a self-test failure. The second self-test unit is, for example, also electrically connected to the second control unit 126 so as to transmit the self-test signal to the second control unit 126, and the second control unit 126 can store the self-test signal.

[0068] When the second current output module 102 is in the working mode, the second self-test unit generates a self-test signal about the second current output module 102 in the working mode, and the second control unit 126 stores the self-test signal.

[0069] The second redundant switching unit 121 may be implemented based on a combinational logic circuit or a sequential logic circuit. The input signal received by the second redundant switching unit 121 may include a reset signal, a switching control signal from the second control unit 126, a self-test signal from the second self-test unit, a self-test signal from the first current output module 101, and a first redundant control signal WORK1 from the first current output module 101. The second redundant switching unit 121 generates a second redundant control signal WORK2 according to the above input signals.

[0070] For example, the reset signal may have the highest priority, that is, when the reset signal is converted from an invalid state to a valid state, the redundant switching module switches the working states of the first current output module and the second current output module. A reset signal in a valid state means that the reset signal is in a state that can produce a reset effect (e.g., a low level state). Correspondingly, a reset signal in an invalid state means that the reset signal is in a state that cannot produce a reset effect (e.g., a high level state). The reset signal may be generated by a control unit or by an external reset circuit. In some embodiments, when a system failure occurs, the reset signal is set to a valid state. Whenever the reset signal is converted from an invalid state to a valid state, the redundant switching module performs a switching operation so that the working states of the first current output module and the second current output module are switched to each other.

[0071] During the operation of the analog current output system 100, if the first control unit 116 generates a switching instruction, the first redundant switching unit 111 generates a first redundant control signal WORK1 representing the right to give up according to the switching instruction, and the first current output module 101 enters the standby mode. In response to the first redundant control signal WORK1 representing the right to give up from the first redundant switching unit 111, the second redundant switching unit 121 generates a second redundant control signal WORK2 representing the right not to give up. According to the second redundant control signal WORK2 representing the right not to give up, the second current output module 102 enters the working mode. The generation of the switching instruction by the first control unit 116 can be regarded as the first control unit 116 controlling the first current output module 101 to "actively give up" and enter the standby mode from the working mode.

[0072] For example, the first current output module 101 is in working mode, and the second current output module 102 is in standby mode. The initial state of the first self-test signal of the first current output module 101 in working mode is, for example, a state indicating that the self-test is normal. When the load RL increases, the driving capability of the first current output module 101 in working mode is insufficient, and a deviation will occur between the current output by the first current source 113 and the set target value. When the deviation is greater than a predetermined threshold, the magnitude of the current output by the first current source 113 detected by the first self-test unit does not meet the predetermined condition, and the first self-test unit generates a first self-test signal indicating a self-test failure. The first self-test signal of the first current output module 101 in working mode is converted from a state indicating that the self-test is normal to a state indicating that the self-test is faulty, and thus the first redundant switching unit 111 generates a first redundant control signal WORK1 indicating that the right is given. In response to the first redundant control signal WORK1 indicating that the right is given, the second redundant switching unit 121 generates a second redundant control signal WORK2 indicating that the right is not given. In response to the first redundant control signal WORK1 (e.g., the high-level first redundant control signal WORK1) indicating the right to give up, the first switch unit 115 is in the on state, the first current source 113 forms a current loop via the first switch unit 115, and the first current output module 101 enters the standby mode. In response to the second redundant control signal WORK2 (e.g., the low-level second redundant control signal WORK2) indicating the right not to give up, the second switch unit 125 is in the off state, the second current source 123 outputs current to the load RL via the second diode D2, and the second current output module 102 enters the working mode.

[0073] After the second current output module 102 enters the working mode (and the first current output module 101 enters the standby mode), the second self-test unit of the second current output module 102 continues to perform current self-test on the second current source 123. Due to the influence of the load RL, the driving capability of the second current output module 102 in the working mode is insufficient, and a deviation will occur between the current output by the second current source 123 and the set target value. When the deviation is greater than a predetermined threshold, the magnitude of the current output by the second current source 123 detected by the second self-test unit does not meet the predetermined condition, and the second self-test unit generates a self-test signal representing a self-test failure. The first control unit 116 stores the self-test signal.

[0074] At this time, the second redundant switching unit 121 generates a redundant control signal indicating non-relinquishment according to the self-test signal indicating a self-test failure, so as to maintain the working state of the first current output module and the second current output module. That is, if the self-test signal generated by the first self-test after any one of the first current output module 101 and the second current output module 102 is switched from the standby mode to the working mode is a self-test signal indicating a self-test failure, the redundant switching module maintains the working state of the first current output module and the second current output module without switching.

[0075] In response to the redundant control signal outputted by the second current output module 102 (i.e., the current output module currently in the working mode) indicating that the power is not yielded, the first current output module 101 (i.e., the current output module currently in the standby mode) maintains the redundant control signal generated by it as a state indicating that the power is yielded. Therefore, the second current output module 102 is maintained in the working mode, and the first current output module 101 is maintained in the standby mode.

[0076] It should be understood that when the load is very large, the driving current of the current source is very small, close to the load disconnection. The load disconnection may be that the channel is not actually used or the load cable is indeed damaged. If the module detects that a channel changes from a non-disconnected state to a disconnected state, a redundant switch is performed. If the line is always disconnected, no switch will be performed. If the line is suddenly disconnected due to an external cable failure, after the switch, the new working module will always detect the disconnection, indicating that it is an external fault and does not meet the conditions for redundant switching, so it will not switch back and forth. If the disconnection is caused by an internal fault of the module, the new working module will work normally after the redundant switching. The redundant switching mechanism of the analog current output system 100 effectively avoids the problem of switching back and forth when the line is not cut or the channel is not used. Therefore, if it is not the fault of the current output module itself, but the self-test fault of the current output module is caused by external reasons (such as the increase of the load RL, etc.), the analog current output system 100 can avoid the two current output modules from switching back and forth fearlessly to ensure the stability of the system.

[0077] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

[0078] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. An analog current output system, characterized in that: include: A first current output module, wherein the current working state of the first current output module is configured as a working mode and outputs current to a load, and the first current output module further generates a first self-test signal regarding the current working state; as well as A second current output module, wherein the current working state of the second current output module is in a standby mode; as well as a redundancy switching module, configured to switch the second current output module to a working mode and the first current output module to a standby mode in response to the first self-test signal being converted from a state indicating a normal self-test to a state indicating a self-test failure, and to maintain the working states of the first current output module and the second current output module in response to the self-test signal indicating a self-test failure within a predetermined time after the second current output module is switched to the working mode; The first current output module also includes: a first power selection unit electrically connected to the first current source, the first power selection unit being configured to output a first voltage to the first current source in response to a first redundant control signal indicating a yield, and to output a second voltage to the first current source in response to a first redundant control signal indicating a non-yield, wherein the first voltage is less than the second voltage; and A first current source, wherein a current output terminal of the first current source is electrically connected to a load; The first current output module also includes: A first redundant control unit is electrically connected to the output end of the first current source and the load, and is configured to make the current output by the first current source be output to the load in response to a first redundant control signal indicating non-yield; The first redundant control unit comprises: A first resistor, one end of the first resistor is configured to receive a first redundant control signal, and the other end of the first resistor is electrically connected to the control end of the first switch unit; a first switch unit, wherein a first end of the first switch unit is electrically connected to a current output end of the first current source, and a second end of the first switch unit is grounded; and a first diode, wherein an anode of the first diode is electrically connected to a current output terminal of the first current source, and a cathode of the first diode is electrically connected to a load; The first switch unit includes a first MOS tube, the gate of the first MOS tube serves as the control terminal of the first switch unit, the drain of the first MOS tube serves as the first terminal of the first switch unit, the source of the first MOS tube serves as the second terminal of the first switch unit, and the drain-source voltage of the first MOS tube when it is turned on is less than the conduction voltage drop of the first diode; or The first switch unit includes a first transistor, the base of the first transistor serves as the control end of the first switch unit, the collector of the first transistor serves as the first end of the first switch unit, and the emitter of the first transistor serves as the second end of the first switch unit. The first transistor is in a saturation state when turned on, so that the conduction voltage drop of the first transistor is less than the conduction voltage drop of the first diode.

2. The analog current output system according to claim 1, characterized in that: The redundant switching module is configured to make the first current output module and the second current output module mutually exclusively in one of a working mode and a standby mode.

3. The analog current output system according to claim 2, characterized in that: The redundant switching module includes: The first redundancy switching unit is configured to generate a first redundancy control signal indicating a right of relinquishment when the first self-test signal is converted from a state indicating a normal self-test to a state indicating a self-test failure, so as to switch the working states of the first current output module and the second current output module.

4. The analog current output system according to claim 1, characterized in that: The first current output module also includes: The first self-test unit is electrically connected to the current output end of the first current source, and is configured to detect whether the current output by the first current source meets a predetermined condition, generate a self-test signal indicating that the self-test is normal in response to determining that the current output by the first current source meets the predetermined condition, and generate a self-test signal indicating that the self-test is faulty in response to determining that the current output by the first current source does not meet the predetermined condition.

5. The analog current output system according to claim 4, characterized in that: The first current output module also includes: A first control unit is configured to generate a switching instruction; The first redundant switching unit is further configured to generate a first redundant control signal representing the right to yield according to the switching instruction.

6. The analog current output system according to claim 4, characterized in that: The redundant switching module is further configured to switch the working states of the first current output module and the second current output module in response to the reset signal being converted from an invalid state to a valid state.

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