Device and method for comprehensively processing analog input signal of industrial system

Abstract

The invention discloses a device for comprehensively processing an analog input signal of an industrial system, and aims to solve the problem that the processing of AI (analog input) input is relatively simple and cannot meet complex requirements at present through a fault self-bypass module, an interlocking output control module, an MOS (metal oxide semiconductor) bypass module and an MOS grouping module. Under the condition that the analog quantity input signal point position participates in SIS interlocking and DCS control, MOS bypass, fault self-bypass and AI interlocking output control functions are achieved for the analog quantity input signal point position, use of operators is facilitated, and working efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of signal processing, and in particular relates to a device and method for comprehensively processing analog input signals of an industrial system. Background Art

[0002] At present, there is no integrated function block for practical application of AI (analog input signal) input in the central control system TCS900. It simply judges the AI ​​input value for interlocking. There are two specific situations: (1) Typical applications It simply compares the real-time value of the input AI, outputs the comparison result, and combines the basic logic unit to build the bypass switch + AI interlocking related functions.

[0003] This application has relatively simple functions and is suitable for general project sites. When facing project sites with complex and high SIS interlocking requirements, this solution cannot meet the requirements, such as fault self-bypass, interlocking dead zone, MOS grouping, etc. Therefore, it cannot meet the increasingly complex actual functional applications.

[0004] (2) Function block application This application simply encapsulates the functions of (1) application into functional blocks, reducing the workload of coding. It does not actually add complex functions and cannot meet the increasingly complex actual functional applications. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for comprehensively processing analog input signals of industrial systems, so as to solve the problem of realizing specific functions of AI analog input signals in practical applications of the central control TCS900 system.

[0006] To solve the above problems, the technical solution of the present invention is: A device for comprehensive processing of analog input signals of an industrial system, comprising: a fault self-bypass module, an interlocking output control module, a MOS bypass module and a MOS grouping module; The MOS bypass module is configured to set a MOS switch on the SIS side and the DCS side when the analog input signal point is used for both SIS interlocking and DCS control. When the analog input signal point is used for both SIS interlocking and DCS control, the MOS switch on the SIS side is used for both MOS switches. When the communication between the DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency. When the communication between the DCS and SIS is interrupted, the MOS switch on the SIS side operates normally. The MOS grouping module is configured to allow only one MOS switch to be put into use in a SIL loop interlock; The fault self-bypass module is configured to automatically cut off the bypass of an analog input signal point when a fault occurs, and the bypass cut lasts for a preset time, generating a bypass alarm; The interlock output control module is configured to output the comparison result between the real-time value of the analog input signal and the interlock value when the interlock vote is triggered; at the same time, determine whether the real-time value of the analog input signal exceeds a preset range, and if so, reset the interlock vote. According to one embodiment of the present invention, the MOS bypass module is also configured to obtain the current bypass output value on the SIS side when any MOS switch is triggered, perform XOR operation on the current bypass output value and the MOS switch feedback value, generate a pulse, start timing, and initialize the SIS bypass output value to MOS bypass; when the pulse time is reached, update the current bypass output value and the SIS bypass output value to the MOS switch feedback value.

[0007] According to an embodiment of the present invention, the MOS grouping module is further configured to set a MOS unlocking switch and an unlocking switch enable. When the unlocking switch enable is turned on, the MOS unlocking switch realizes arbitrary switching of the MOS switch.

[0008] According to an embodiment of the present invention, the MOS grouping module includes a plurality of inputs. When the number of input MOS switches exceeds a preset number, a new MOS grouping module is added and connected in a cascade manner.

[0009] According to one embodiment of the present invention, the fault self-bypass module is also configured to cancel the fault bypass when the bypass of the faulty analog input signal point reaches a preset time, or the MOS bypass corresponding to the bypassed analog input signal point is activated.

[0010] According to an embodiment of the present invention, the interlock output control module sets the interlock value to be between the minimum analog input signal value and the maximum analog input signal value to prevent interlock output errors.

[0011] A method for comprehensively processing analog input signals of an industrial system, comprising: When the analog input signal point participates in both SIS interlocking and DCS control, when setting MOS bypass for the analog input signal point, MOS switches need to be set on both the SIS side and the DCS side; when the communication between DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency; when the communication between DCS and SIS is interrupted, the MOS switch on the SIS side operates normally; MOS bypasses are grouped so that only one MOS switch is allowed to be used in a SIL loop interlock. When an analog input signal point fails, its bypass is automatically cut off, and after the bypass is cut off for a preset time, a bypass alarm is generated to realize the fault self-bypass function; When the interlocking vote is triggered, the comparison result between the real-time value of the analog input signal and the interlocking value is output; at the same time, it is determined whether the real-time value of the analog input signal exceeds the preset range. If so, the interlocking vote is reset.

[0012] According to an embodiment of the present invention, when the communication between the DCS and the SIS is normal, the consistency processing of the states of the MOS switches on both sides further includes: When any MOS switch changes, the SIS side monitors the MOS switch state. If a change occurs, a pulse timing is triggered. During the timing time, the output of the MOS switch is synchronized to be consistent with the bypass state. After the timing ends, the MOS switch output is synchronized with the bypass state feedback value. At the same time, on the DCS side, it is determined whether the MOS switch is actuated. If so, the timing starts. During the timing process, the DCS bypass output is consistent with the MOS switch state. After the timing ends, the DCS bypass output is consistent with the bypass state communicated by the SIS. If the MOS switch does not act, it is detected whether the bypass state communicated by the SIS has changed. If so, the DCS bypass output value is updated to be consistent with the bypass state communicated by the SIS.

[0013] According to one embodiment of the present invention, when performing MOS grouping, the number of MOS group input bypass switches that are ON is counted to determine whether the MOS enable switch is ON. If so, it is further determined whether the MOS unlock switch is ON. If so, switching is performed according to the number of input MOS switches; if not, it is further determined whether the number of input MOS switches is greater than 1. If not, switching is performed according to the number of input MOS switches; if so, MOS switch switching is performed once; at the same time, when the MOS enable switch is OFF, MOS switch switching is also performed once.

[0014] According to an embodiment of the present invention, when interlock voting is performed, the interlock value is set between the minimum analog input signal value and the maximum analog input signal value to prevent interlock output errors.

[0015] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: In one embodiment of the present invention, a device for comprehensively processing analog input signals of an industrial system aims at the problem that the current processing of AI input is relatively simple and cannot meet complex requirements. By means of a fault self-bypass module, an interlocking output control module, a MOS bypass module and a MOS grouping module, when an analog input signal point participates in both SIS interlocking and DCS control, when a MOS bypass is set for the analog input signal point, a MOS switch needs to be set on each of the SIS side and the DCS side; when the communication between the DCS and the SIS is normal, the states of the MOS switches on both sides are processed for consistency; when the communication between the DCS and the SIS is interrupted, the MOS switch on the SIS side operates normally; in a SIL loop interlocking, only one MOS switch is allowed to be put into use; when an analog input signal point fails, its bypass is automatically cut off, and the bypass cut off lasts for a preset time, generating a bypass alarm; when the interlocking vote is triggered, the comparison result between the real-time value of the analog input signal and the interlocking value is output; at the same time, it is judged whether the real-time value of the analog input signal exceeds the preset range, and if so, the interlocking vote is reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A block diagram of a device for comprehensively processing analog input signals of an industrial system in one embodiment of the present invention; Figure 2 is a logic flow chart of MOS bypass on the SIS side in one embodiment of the present invention; Figure 3 is a logic flow chart of the MOS bypass on the DCS side in one embodiment of the present invention; Figure 4 A code diagram of MOS bypass processing in one embodiment of the present invention; Figure 5 is a logic flow chart of MOS grouping in one embodiment of the present invention; Figure 6 A schematic diagram of cascading MOS grouping function blocks in an embodiment of the present invention; Figure 7 A diagram showing the joint construction of MOS bypass and MOS grouping functional blocks in one embodiment of the present invention; Figure 8 is a fault self-bypass logic flow chart in one embodiment of the present invention; Fig. 9 A fault self-bypass code diagram in one embodiment of the present invention; Fig.10 A schematic diagram of a fault self-bypass module in an embodiment of the present invention; Fig.11 The figure is a logic flow chart of AI interlock output in one embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following is a further detailed description of a device and method for comprehensively processing analog input signals of an industrial system proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0018] Please see Figure 1 ,This embodiment provides a device for comprehensive processing of analog input signals of an industrial system, including: a fault self-bypass module, an interlocking output control module, a MOS bypass module and a MOS grouping module; Among them, the MOS bypass module is configured to set MOS switches on the SIS side and the DCS side when the analog input signal point participates in both SIS interlocking and DCS control. When the analog input signal point is set to MOS bypass, the MOS switches on both sides need to be set; when the communication between DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency; when the communication between DCS and SIS is interrupted, the MOS switch on the SIS side operates normally. The MOS grouping module is configured to allow only one MOS switch to be put into use in a SIL loop interlock; The fault self-bypass module is configured to automatically cut off the bypass when a fault occurs at an analog input signal point, and the bypass cut lasts for a preset time, generating a bypass alarm; The interlock output control module is configured to output the comparison result between the real-time value of the analog input signal and the interlock value when the interlock vote is triggered; at the same time, it determines whether the real-time value of the analog input signal exceeds the preset range. If so, the interlock vote is reset.

[0019] Furthermore, the MOS bypass module is also configured to obtain the current bypass output value on the SIS side when any MOS switch is triggered, perform XOR operation on the current bypass output value and the MOS switch feedback value, generate a pulse, start timing, and initialize the SIS bypass output value to MOS bypass; when the pulse time is reached, update the current bypass output value and the SIS bypass output value to the MOS switch feedback value.

[0020] The MOS grouping module is further configured to set a MOS unlocking switch and an unlocking switch enable. When the unlocking switch enable is turned on, the MOS unlocking switch realizes arbitrary switching of the MOS switch.

[0021] The MOS grouping module includes multiple inputs. When the number of input MOS switches exceeds a preset number, a new MOS grouping module is added and connected in a cascade manner.

[0022] The fault self-bypass module is also configured to cancel the fault bypass when the bypass of the faulty analog input signal point reaches a preset time, or the MOS bypass corresponding to the bypassed analog input signal point is activated.

[0023] The interlock output control module sets the interlock value between the minimum analog input signal value and the maximum analog input signal value to prevent interlock output errors.

[0024] The above device realizes the functions of fault self-bypass, interlocking dead zone, MOS grouping and MOS bypass, etc., which can meet the increasingly complex practical functional applications.

[0025] The device is mainly used for the realization of fault self-bypass, interlocking control and MOS bypass control functions of the current central control TCS900 system for the on-site analog instrument input. The following is a specific example to introduce the function realization and processing method of the device.

[0026] The SIS system of a certain device has 4 corresponding pressure gauges connected on site, and the relevant interlocking action plan needs to be built. The device also has a DCS control system. In terms of personnel operation arrangements, the process operators operate on the DCS side on a daily basis, and the relevant SIS field instruments need to be repaired and maintained.

[0027] An auxiliary operation console of the SIS system needs to be placed on the CCR side. The auxiliary operation console needs to be set with a MOS enable switch to control the authority of the MOS switch of the SIS.

[0028] In addition, in order to avoid triggering more important on-site interlocking circuits due to SIS instrument failures, based on the principle of fault-oriented safety, it is necessary to set up a fault self-bypass function.

[0029] For the above-mentioned field devices, it is necessary to set up a MOS bypass for the field pressure gauge as required. The conventional solution is to only set up the relevant MOS switch in the SIS system for bypass interlocking. This example takes into account that the SIS system is generally in static monitoring, and all factories will not arrange permanent SIS operators. In order to make the MOS operation management more adaptable to the field operator arrangement, this example sets up corresponding MOS switches on both the SIS and DCS systems. Considering the independence requirements of the system, the data exchange of the MOS switches on both sides is transmitted by communication.

[0030] At the same time, in order to ensure the effectiveness and uniqueness of MOS operation, the MOS switch status of DCS and SIS should be consistent when the device system is operating normally, and the status of the two states needs to introduce consistent functional processing. In the abnormal case of DCS and SIS communication interruption, the MOS switch on the SIS side should be able to operate normally.

[0031] The above MOS bypass function is implemented by encapsulating the software code of PLC to improve the usability and work efficiency. The encapsulated function block, namely the MOS bypass module, is configured to set MOS switches on the SIS side and the DCS side when setting MOS bypass for the analog input signal point when the analog input signal point participates in both SIS interlocking and DCS control; when the communication between DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency; when the communication between DCS and SIS is interrupted, the MOS switch on the SIS side operates normally.

[0032] For details, please see Figure 2 When any MOS switch changes, the MOS switch status is monitored on the SIS side. If a change occurs, the pulse timing T01 is triggered. During the T01 timing time, the output of the MOS switch is synchronized to be consistent with the bypass switch. After the T01 timing ends, the MOS switch output is synchronized with the MOS bypass status feedback value.

[0033] Also, see Figure 3 When any MOS switch is triggered, the DCS side determines whether the MOS switch is in action. If so, it starts timing T01. During the timing process, the DCS bypass output is consistent with the bypass switch state (used to synchronize the bypass output of SIS to be consistent with DCS); after T01 timing ends, the DCS bypass output is consistent with the bypass state communicated by SIS. If the DCS bypass switch does not act, it detects whether the bypass state communicated by SIS has changed (whether SIS bypasses). If so, the DCS bypass output value is updated to be consistent with the bypass state communicated by SIS.

[0034] For the custom code implementation of the MOS bypass module, please refer to Figure 4 In the figure, parameter MOS_DCS is the MOS bypass identifier on the DCS side, MOS_SIS is the MOS bypass identifier on the SIS side, STA_MOS is the MOS switch feedback identifier, O_MOS is the MOS bypass output identifier, O_MOS_SIS is the MOS bypass output identifier on the SIS side, MOS_SIS_O is the MOS switching identifier on the SIS side, and MOS_DCS_O is the MOS switching identifier on the DCS side.

[0035] For the same SIL loop interlock, in order to improve the reliability of normal operation of the interlock and reduce the random switching of MOS, the MOS grouping function is specially introduced. This function limits a SIL loop. If there is no special requirement, only one MOS switch is allowed to be put into use. The purpose is to better put the interlock into use and ensure the normal monitoring of the loop. The SIL loop is a control loop composed of software simulation. It is mainly used to verify and test complex systems to ensure that the system can work normally under various different situations.

[0036] At the same time, in order to be applicable to emergency situations, the restriction has an unlocking function. Once unlocked, the MOS switch can be switched at will, and the unlocking switch can be included in the authority management.

[0037] In addition, in order to prevent process operators from unauthorized operation of the MOS switch, a MOS enable switch restriction is added. When the enable switch is enabled, the MOS switch input and output will be effective.

[0038] The function of MOS grouping is mainly to Figure 3 The STA_MOS parameter shown is the output parameter of this function. This function is implemented by encapsulating the PLC software code to improve the usability and work efficiency. The encapsulated module, namely the MOS grouping module, can be found in Figure 5 , the logic implementation of the MOS grouping module includes the following steps: Count the number of MOS group input bypass switches that are ON, determine whether the MOS enable switch is ON, if so, further determine whether the MOS unlock switch is ON, if so, perform switching according to the number of MOS switches input; if not, further determine whether the number of MOS switches input is greater than 1, if not, perform switching according to the number of MOS switches input; if yes, perform a MOS switch switching. At the same time, when the MOS enable switch is OFF, a MOS switch switching is also performed.

[0039] When the number of MOS groups exceeds the 16 inputs of the function block, two function blocks need to be cascaded, and the input parameter MOS_RUN is involved, which is the output O_MOS_RUN of the remaining cascaded MOS group function blocks. In this embodiment, the bypass switches of the device 4 pressure gauges are respectively set with two function blocks, and the cascade diagram is as follows Figure 6 As shown, when multiple function blocks are cascaded, it is achieved through the MOS_RUN and O_MOS_RUN parameters.

[0040] The above MOS bypass module and MOS grouping module need to be used together. For module construction, please refer to Figure 7In the figure, the red and orange ones are the parameter transfer of the two modules, the blue one MOS_EN is the MOS enable switch, and MOS_Unlock is the MOS unlock switch.

[0041] The fault self-bypass function in this embodiment is mainly to realize that when a certain AI point fails, it is required to automatically cut off its bypass and maintain the pre-set bypass time, generating a bypass alarm. During this period of time, if the corresponding MOS switch is triggered or expires, the fault bypass is cancelled. If the corresponding pressure gauge is configured with a fail-safe value, an interlock will be triggered. The implementation of the fault self-bypass function is encapsulated using the PLC software code. For its logical implementation, please refer to Figure 8 In the figure, AM_EN is the fault self-bypass enable, AI_OK is the normal AI channel, AUTO_MOS is the fault self-bypass mark, AM_T_S is the fault self-bypass time, and ERR_MOS is the AI ​​fault bypass mark. For the function code of the fault self-bypass module, please refer to Fig. 9 .

[0042] In actual application, when the pressure gauge 01PT_1001 fails, the instrument is automatically bypassed for 15 seconds. Fig.10 ,In the figure, O_ERR_MOS is the output bit of the fault bypass, which can be connected to ,related variables for alarm prompts.

[0043] Regarding AI interlock output control, this part of the function is implemented in the SIS system. A common requirement is to compare the data transmitted by the field instrument with the size of the preset interlock value and vote on the output logic result. This embodiment combines the above-mentioned MOS bypass module and the fault self-bypass module to add an interlock reset dead zone to the AI ​​interlock output control. That is, when the real-time value of the AI ​​input signal fluctuates near the interlock value, frequent actions of the interlock voting output will occur. To avoid this situation, a comparison dead zone function is introduced. When the interlock voting is triggered, the interlock voting will only be reset when the real-time value of AI exceeds the setting range of the dead zone.

[0044] At the same time, an error-proofing function is added to the setting of the interlock value, requiring that the setting of the interlock value must be within the AI ​​range, that is, between the maximum AI value and the minimum AI value.

[0045] In this embodiment, the function of AI interlocking output control is encapsulated through the software code of PLC to obtain an interlocking output control module, and four interlocking outputs are set for the interlocking output control module, namely HH / H / L / LL. Due to the repeatability, the logic of the module is explained below using HH interlocking output as an example.

[0046] Please see Fig.11, first determine whether the interlock setting value is within the AI ​​range. If so, further determine whether the MOS bypass is activated. If so, the voting output result is ON. If the interlock setting value is not within the AI ​​range, reset the interlock value to determine whether the MOS bypass is activated. If not, determine whether the interlock output is triggered. If so, determine whether the AI ​​real-time value exceeds the interlock reset dead zone. If so, the output voting result is OFF. If the interlock output is not activated, determine whether the AI ​​real-time value is greater than or equal to the interlock value. If so, activate the interlock output and output the voting result as OFF.

[0047] In summary, this embodiment provides a solution for setting up MOS switches in both SIS and DCS, systematically organizes the related controls of AI analog quantities, and performs modularization and standardization, thereby facilitating operation and improving work efficiency.

[0048] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A device for comprehensive processing of analog input signals of an industrial system, characterized in that: include: Fault self-bypass module, interlocking output control module, MOS bypass module and MOS grouping module; The MOS bypass module is configured to set a MOS switch on the SIS side and the DCS side when the analog input signal point is used for both SIS interlocking and DCS control. When the analog input signal point is used for both SIS interlocking and DCS control, the MOS switch on the SIS side is used for both MOS switches. When the communication between the DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency. When the communication between the DCS and SIS is interrupted, the MOS switch on the SIS side operates normally. The MOS grouping module is configured to allow only one MOS switch to be put into use in a SIL loop interlock; The fault self-bypass module is configured to automatically cut off the bypass of an analog input signal point when a fault occurs, and the bypass cut lasts for a preset time, generating a bypass alarm; The interlock output control module is configured to output the comparison result between the real-time value of the analog input signal and the interlock value when the interlock vote is triggered; at the same time, determine whether the real-time value of the analog input signal exceeds a preset range, and if so, reset the interlock vote.

2. The device for comprehensively processing analog input signals of an industrial system according to claim 1, characterized in that: The MOS bypass module is further configured to obtain a current bypass output value on the SIS side when any MOS switch is triggered, perform XOR operation on the current bypass output value and the MOS switch feedback value, generate a pulse, start timing, and initialize the SIS bypass output value to MOS bypass; When the pulse time is reached, the current bypass output value and the SIS bypass output value are updated to the MOS switch feedback value.

3. The device for comprehensively processing analog input signals of an industrial system according to claim 1, characterized in that: The MOS grouping module is further configured to set a MOS unlocking switch and an unlocking switch enable. When the unlocking switch enable is turned on, the MOS unlocking switch realizes arbitrary switching of the MOS switch.

4. The device for comprehensively processing analog input signals of an industrial system as claimed in claim 3, characterized in that: The MOS grouping module includes multiple inputs. When the number of input MOS switches exceeds a preset number, a new MOS grouping module is added and connected in a cascade manner.

5. The device for comprehensively processing analog input signals of an industrial system according to claim 1, characterized in that: The fault self-bypass module is also configured to cancel the fault bypass when the bypass of the faulty analog input signal point reaches a preset time, or when the MOS bypass corresponding to the bypassed analog input signal point is activated.

6. The device for comprehensively processing analog input signals of an industrial system according to claim 1, characterized in that: The interlock output control module sets the interlock value to between the minimum analog input signal value and the maximum analog input signal value to prevent interlock output errors.

7. A method for comprehensive processing of analog input signals of an industrial system, characterized in that: include: When the analog input signal point participates in both SIS interlocking and DCS control, when setting MOS bypass for the analog input signal point, MOS switches need to be set on both the SIS side and the DCS side; when the communication between DCS and SIS is normal, the states of the MOS switches on both sides are processed for consistency; when the communication between DCS and SIS is interrupted, the MOS switch on the SIS side operates normally; MOS bypasses are grouped so that only one MOS switch is allowed to be used in a SIL loop interlock. When an analog input signal point fails, its bypass is automatically cut off, and after the bypass is cut off for a preset time, a bypass alarm is generated to realize the fault self-bypass function; When the interlocking vote is triggered, the comparison result between the real-time value of the analog input signal and the interlocking value is output; at the same time, it is determined whether the real-time value of the analog input signal exceeds the preset range. If so, the interlocking vote is reset.

8. The method for comprehensively processing analog input signals of an industrial system according to claim 7, characterized in that: When the communication between DCS and SIS is normal, the consistency processing of the states of the MOS switches on both sides further includes: When any MOS switch changes, the SIS monitors the MOS switch status. If a change occurs, the pulse timing is triggered. During the timing time, the output of the MOS switch is synchronized to be consistent with the bypass status. After the timing ends, the MOS switch output is synchronized with the bypass status feedback value. At the same time, on the DCS side, it is determined whether the MOS switch is actuated. If so, the timing starts. During the timing process, the DCS bypass output is consistent with the MOS switch state. After the timing ends, the DCS bypass output is consistent with the bypass state communicated by the SIS. If the MOS switch does not act, it is detected whether the bypass state communicated by the SIS has changed. If so, the DCS bypass output value is updated to be consistent with the bypass state communicated by the SIS.

9. The method for comprehensively processing analog input signals of an industrial system according to claim 7, characterized in that: When performing MOS grouping, count the number of MOS group input bypass switches that are ON, and determine whether the MOS enable switch is ON. If so, further determine whether the MOS unlock switch is ON. If so, perform switching according to the number of input MOS switches; if not, further determine whether the number of input MOS switches is greater than 1. If not, perform switching according to the number of input MOS switches; if so, perform one MOS switch switching; at the same time, when the MOS enable switch is OFF, also perform one MOS switch switching.

10. The method for comprehensively processing analog input signals of an industrial system according to claim 7, characterized in that: When performing interlock voting, set the interlock value between the minimum analog input signal value and the maximum analog input signal value to prevent interlock output errors.

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