Intelligent connecting device supporting multiple master devices and multiple slave devices
By designing an intelligent connection device that supports multiple masters and slaves, integrating a power module, connection module, control module, isolation module, and human-machine interface, the problems of reading conflicts and data errors in traditional communication architectures are solved, achieving stable and flexible multi-device communication and efficient operation and maintenance.
Patent Information
- Application Number
- CN202521765417.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2035-08-19
AI Technical Summary
Traditional master-slave communication architectures are prone to read conflicts and data errors when multiple hosts are connected to the same bus, resulting in decreased communication stability and data accuracy. Furthermore, they are costly to construct and upgrade, cannot flexibly adapt to the dynamic business needs of multiple masters and slaves, lack visual feedback methods, and have low operation and maintenance efficiency.
Design an intelligent connection device that supports multiple masters and slaves, including a power module, a connection module, a control module, an isolation module, a human-machine interface, and a base fixing module. By integrating these modules, stable power supply, master-slave line connection, multi-master and multi-slave scheduling and priority management, interference isolation, and visual operation are achieved, adapting to complex field installation requirements.
It enables flexible connection between multiple master and slave devices, reduces construction and renovation costs, improves communication stability and intelligence, supports collaborative communication among multiple devices, simplifies operation and maintenance processes, improves fault diagnosis efficiency, and adapts to complex power supply environments and diverse installation scenarios.
Smart Images
Figure CN223502879U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of power communication technology, specifically to an intelligent connection device that supports multiple masters and multiple slaves. Background Technology
[0002] In power data acquisition and similar multi-device communication scenarios, traditional master-slave communication architectures often adopt a one-master-multiple-slave, direct-connection mode. While this can meet basic data interaction needs, with the expansion of power market business, application scenarios have emerged where multiple masters simultaneously read data from multiple slaves. However, under the existing architecture, when multiple masters are connected to the same bus, reading conflicts and data errors are prone to occur due to bus contention, seriously affecting communication stability and data accuracy. To solve these problems, existing solutions often choose to re-lay master-slave connection lines or increase the number of slaves to ensure that only a single master exists on the bus. This not only significantly increases the difficulty and cost of on-site construction and transformation, but also wastes resources due to additional wiring and equipment additions. Furthermore, it cannot flexibly adapt to the dynamically changing business needs of multiple masters and multiple slaves, restricting the efficiency and intelligent development of multi-device collaborative communication in the power and related industries. At the same time, the lack of visual feedback means for master-slave wiring status and communication status makes it difficult for maintenance personnel to troubleshoot in a timely manner, further reducing system reliability and maintenance efficiency, and failing to meet the high requirements of modern power and industrial communication for stability, intelligence, and ease of maintenance. Utility Model Content
[0003] The embodiments of this utility model provide an intelligent connection device that supports multiple masters and multiple slaves, aiming to solve the problems mentioned above in the background art.
[0004] To achieve the above objectives, this utility model provides an intelligent connection device supporting multiple masters and multiple slaves, comprising:
[0005] A power module used to provide AC or DC power to the device;
[0006] A connection module used to enable line connection between the host and slave devices;
[0007] The control module is used to perform multi-master multi-slave connection scheduling and priority management functions;
[0008] An isolation module used to prevent interference between the connection module and the control module;
[0009] Human-computer interaction interface used to realize human-computer information interaction;
[0010] A base fixing module used to fix the device in place;
[0011] The power module includes a housing, the connection module is installed on the outside of the housing, the control module is installed inside the housing, the isolation module is located inside the housing, the human-machine interface is installed on the top of the housing, and the base fixing module is installed on the bottom of the housing.
[0012] As a preferred embodiment of this utility model, the outer shell is made of metal or flame-retardant insulating material, and the inner part of the outer shell is also provided with an AC / DC conversion circuit, which outputs two DC power supplies.
[0013] As a preferred embodiment of this utility model, the connection module includes a host terminal block group located on one side of the housing and a slave terminal block group located on the other side of the housing. The host terminal block group includes at least 16 terminals corresponding to 8 sets of connection channels, and each set of connection channels is adapted to 2 host terminals. The slave terminal block group includes several terminals corresponding to the 8 sets of connection channels, and each set of connection channels is adapted to multiple slave terminals.
[0014] As a preferred embodiment of this utility model, the control module consists of 8 independent control sub-modules, each corresponding to 8 connection channels. Each control sub-module integrates a microcontroller, a storage unit, and a communication interface. The communication interface is used for data interaction with the isolation module and the human-machine interface.
[0015] In a preferred embodiment of this utility model, the wiring status of the host terminal block and the slave terminal block is displayed by an indicator light group provided on the human-machine interface.
[0016] In a preferred embodiment of this utility model, the isolation module is an isolation component, which is an opto-isolator or an electromagnetic isolator. The input end of the isolation component is connected to the signal output end of the connection module via a wire, and the output end is connected to the signal input end of the control module. The isolation component internally cuts off the electrical interference path between the connection module and the control module through an optocoupler or an isolation coil.
[0017] As a preferred embodiment of this utility model, the human-machine interface includes a liquid crystal display unit installed on the top of the housing. The liquid crystal display unit is connected to the display driver interface of the control module via a ribbon cable. A button group is also provided around the liquid crystal display unit. The button group is connected to the button input interface of the control module via a button circuit. The human-machine interface also includes an indicator light group distributed on the surface of the housing. The indicator light group is electrically connected to the control module via an indicator light driver circuit.
[0018] As a preferred embodiment of this utility model, the base fixing module includes a guide rail type mounting buckle disposed on the back of the bottom of the outer shell. The guide rail type mounting buckle includes a horizontal guide rail adapter buckle and a vertical guide rail adapter buckle. The horizontal guide rail adapter buckle and the vertical guide rail adapter buckle are made of metal springs or plastic materials. The base fixing module also includes multiple fixing mounting screw holes opened on both sides of the bottom of the outer shell.
[0019] Compared with the prior art, the beneficial effects of this utility model are:
[0020] 1) This utility model integrates a power supply module, a connection module, a control module, an isolation module, a human-machine interface, and a base fixing module to form a complete multi-master and multi-slave intelligent connection system. The power supply module provides stable AC / DC power supply to the device, the connection module realizes the line connection between the master and slave devices, the control module performs multi-master and multi-slave scheduling and priority management, the isolation module avoids interference between the lines and the control unit, the human-machine interface realizes information interaction, and the base fixing module ensures installation and fixation. The modules work together to solve the bus conflict problem of the traditional single-master and multi-slave architecture, support flexible connection of multiple masters and multiple slave devices, expand the communication architecture without rewiring, reduce construction and transformation costs, and improve the stability and intelligence level of multi-device collaborative communication.
[0021] 2) The outer shell of this utility model is made of metal or flame-retardant insulating material, which improves the anti-interference and safety of the device. The internal AC-DC conversion circuit outputs two DC power supplies, which are compatible with 220V±50% AC and 5-42V DC power supply environments, meet the power supply needs of complex field sites, and provide reliable power support for multi-master and multi-slave communication.
[0022] 3) The connection module of this utility model supports 8 independent channel configurations through the corresponding design of the host terminal block and the slave terminal block, and can connect up to 16 hosts and multiple slaves, realizing dynamic connection of multiple hosts and multiple slaves. It can expand the communication scale without additional wiring and reduce the difficulty of transformation.
[0023] 4) Each independent control submodule of this utility model corresponds to 8 channels, integrating a microcontroller, storage unit and communication interface. It accurately realizes connection scheduling and priority management through a preset scheduling program, solves multi-master contention conflicts and improves the accuracy of data interaction.
[0024] 5) The wiring status of the host and slave devices in this utility model is displayed by indicator light groups, which provides intuitive feedback on the connection status, facilitates quick troubleshooting of wiring faults, and improves operation and maintenance efficiency;
[0025] 6) The isolation module of this utility model adopts photoelectric or electromagnetic isolation components, cuts off the electrical interference path through optocoupler elements or isolation coils, and the isolation voltage is greater than 5000V, ensuring the stable operation of the control module logic and avoiding communication errors caused by interference;
[0026] 7) The LCD display unit, button group and indicator light group of the human-machine interface of this utility model realize the visual operation of connection configuration, status monitoring and fault feedback, which makes it easy for users to grasp the equipment operating status in real time and simplify the operation and maintenance process.
[0027] 8) The combination of guide rail mounting buckle and fixing screw hole of the base fixing module of this utility model is suitable for various installation scenarios such as guide rail mounting and wall fixing, which improves the deployment flexibility of the device and meets different on-site installation needs. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the overall structure of this utility model;
[0029] Figure 2 This is one of the structural schematic diagrams of this utility model;
[0030] Figure 3 This is a plan view of the present invention;
[0031] Figure 4 This is a schematic diagram of the internal structure of this utility model.
[0032] In the diagram: 1. Power module; 100. Housing; 2. Connection module; 201. Main unit terminal block; 202. Slave unit terminal block; 3. Control module; 301. Control sub-module; 4. Isolation module; 401. Isolation component; 5. Human-machine interface; 501. LCD display unit; 502. Button group; 503. Indicator light group; 6. Base fixing module; 601. Rail mounting clip; 6011. Horizontal rail adapter clip; 6012. Vertical rail adapter clip; 602. Fixing screw holes. Detailed Implementation
[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0034] Example 1
[0035] Please see Figures 1-4This utility model provides an intelligent connection device that supports multiple masters and multiple slaves, including: a power supply module 1 for providing AC and DC power to the device, a connection module 2 for realizing the connection between the master and slave devices, a control module 3 for performing multi-master and multi-slave connection scheduling and priority management functions, an isolation module 4 for preventing interference between the connection module 2 and the control module 3, a human-machine interface 5 for realizing human-machine information interaction, and a base fixing module 6 for fixing the device.
[0036] The power module 1 includes a housing 100, a connection module 2 installed on the outside of the housing 100, a control module 3 installed inside the housing 100, an isolation module 4 located inside the housing 100, a human-machine interface 5 installed on the top of the housing 100, and a base fixing module 6 installed on the bottom of the housing 100.
[0037] Specifically, in a multi-master, multi-slave communication scenario, the outer casing 100 of the power module 1 provides physical protection and a foundation for the internal circuitry. The connection module 2 is installed on the outside of the casing 100 for easy wiring between the master and slave devices. The control module 3 is placed inside to ensure a stable operating environment. When multiple masters and slaves are connected, the power module 1 adapts to the field power supply through AC / DC conversion, providing power to the intelligent connection device and connection channel. The master terminal block 201 and slave terminal block 202 of the connection module 2 establish a physical connection between the master and slave devices. The isolation module 4 connects the module 2 and the control module 3 inside the casing 100 to prevent bus interference from intruding into the control unit. The human-machine interface 5 facilitates operation and status monitoring for maintenance personnel. The base fixing module 6, through its bottom mounting structure, allows for convenient and stable installation of the intelligent connection device on the guide rail or cabinet, efficiently realizing multi-master, multi-slave intelligent connection and scheduling, and adapting to complex field deployment requirements.
[0038] In this embodiment: the outer casing 100 is made of metal or flame-retardant insulating material, and the outer casing 100 is also equipped with an AC-DC conversion circuit. The AC power supply is adapted to a voltage range of 220V±50%, and the DC power supply is adapted to a voltage range of 5-42V. The AC-DC conversion circuit outputs two DC power supplies. One is connected to the core board power supply interface through an internal wire, and the other is connected to the connection channel power supply circuit. The isolation voltage between the two DC power supplies is greater than 4000V. Isolation is achieved through an isolation transformer or optocoupler isolation element in the power module 1.
[0039] Specifically, in complex outdoor or industrial power supply scenarios, when there is AC 220V mains power on site, the outer shell made of metal or flame-retardant insulating material can effectively resist external physical and electrical interference. The internal AC-DC conversion circuit converts 220V±50% AC or 5-42V DC into a usable power supply for intelligent connected devices.
[0040] When multiple hosts initiate communication simultaneously, two DC power supplies are output. One supply powers the core board of control module 3 via a wire, ensuring the stability of the control logic. The other supply powers the connection channel. The isolation transformer or optocoupler isolation element ensures that the isolation voltage between the two DC power supplies is >4000V, avoiding power crosstalk from affecting master-slave communication scheduling. This ensures that the device provides continuous, stable, and interference-resistant power support for multi-master and multi-slave connections under different power supply conditions, making it suitable for diverse power supply environments such as remote power stations and factory workshops.
[0041] In this embodiment: the connection module 2 includes a host terminal block 201 located on one side of the housing 100 and a slave terminal block 202 located on the other side of the housing 100. The host terminal block 201 includes at least 16 terminals, corresponding to 8 connection channels (CH1-CH8). Each connection channel is adapted to 2 host terminals (M1, M2). The slave terminal block 202 includes several slave terminal blocks 202 corresponding to the 8 connection channels. Each connection channel can be adapted to multiple slave terminals (SL). Both the host terminal block and the slave terminal block adopt a plug-in or screw-press-in structure that is convenient for wiring and maintenance.
[0042] Specifically, in multi-master and multi-slave meter reading operations, when maintenance personnel need to connect multiple master and slave meters, they utilize the master terminal block 201 and slave terminal block 202 on both sides of the casing 100 to connect the master meters to the M1 and M2 terminals of the corresponding connection channels (CH1-CH8) according to business requirements, and connect the slave meters to the slave terminal blocks. Since both master and slave terminal blocks use plug-in or screw-press connection, wiring can be completed quickly. When all 8 connection channels are fully configured, the 16 master terminal blocks 201 can connect 16 master meters, and the slave terminal blocks 202 can connect multiple slave meters as needed, realizing multi-master and multi-slave parallel connection without additional wiring. This adapts to the multi-master collaborative and multi-slave data acquisition workflow of power inspection, simplifies on-site wiring operations, and improves deployment efficiency.
[0043] In this embodiment: the control module 3 consists of 8 independent control sub-modules 301, each corresponding to 8 connection channels. Each control sub-module 301 integrates a microcontroller (MCU), a storage unit, and a communication interface. The microcontroller has a fixed priority scheduler and a time priority scheduler. The storage unit is used to store the connection channel configuration information and priority rules. The communication interface is used to interact with the isolation module 4 and the human-machine interface 5.
[0044] Specifically, when multiple systems collect power data in parallel, that is, when multiple hosts compete to access slave devices, the 8 independent control submodules 301 correspond to 8 connection channels (CH1-CH8). When multiple hosts initiate slave access through connection module 2, the microcontroller of control submodule 301 responds according to a preset program. The preset program is existing technology. When it is a fixed priority scenario where important hosts take priority, the priority rules of the storage unit trigger high-priority scheduling to ensure priority communication for critical hosts. When it is a time priority scenario where it is first-in-first-out, it is executed according to the "first-in-first-out" principle.
[0045] The communication interface is set to receive master-slave signals from the real-time interactive isolation module 4 and configuration instructions from the human-machine interface 5. The storage unit records the number of master accesses, slave addresses, and other connection parameters of the connection channels, ensuring that the 8 sets of connection channels are independently scheduled, avoiding multi-master contention conflicts, and adapting to the collaborative and differentiated priority requirements of multiple power data acquisition systems.
[0046] In this embodiment: the isolation module 4 is an opto-isolation or electromagnetic isolation component 401. The input end of the isolation component 401 is connected to the signal output end of the connection module 2 through a wire, and the output end is connected to the signal input end of the control module 3. The isolation voltage of the isolation component 401 is greater than 5000V. The internal optical coupler element or isolation coil cuts off the electrical interference path between the connection module 2 and the control module 3.
[0047] Specifically, in a highly interfering industrial environment such as a factory power distribution room with interference sources like motor start-stop, after the connection module 2 is connected to multiple master and slave devices, the bus interference signal enters the signal output terminal of the connection module 2 through the master and slave terminals. The isolation component 401 of the isolation module 4 receives the signal from the connection module 2 through the input terminal wire and uses an optocoupler or isolation coil to cut off the electrical interference path between the connection module 2 and the signal input terminal of the control module 3, ensuring that the isolation voltage is >5000V. When multiple masters communicate simultaneously and generate complex interference, the isolation component 401 ensures that the control module 3 receives a clean and stable signal, ensuring the stable execution of the scheduling program of the control submodule 301, avoiding interference that causes scheduling logic confusion and data errors, and adapting to reliable multi-master and multi-slave communication in a highly interfering environment.
[0048] In this embodiment: the human-machine interface 5 includes a liquid crystal display unit 501 installed on the top of the housing 100. The liquid crystal display unit 501 is connected to the display driver interface of the control module 3 via a ribbon cable. The liquid crystal display unit 501 is also provided with a button group 502 around it. The button group 502 is connected to the button input interface of the control module 3 via a button circuit. The human-machine interface 5 also includes an indicator light group 503 distributed on the surface of the housing 100. The indicator light group 503 is electrically connected to the control module 3 via an indicator light driver circuit.
[0049] Specifically, when power maintenance personnel are troubleshooting multi-master / multi-slave communication faults and performing maintenance on intelligent connection devices, when the multi-master / multi-slave devices are connected and communicating, the control module 3 collects connection status and data interaction information, and transmits it to the top LCD display unit 501 via a ribbon cable. The display shows the master / slave connection configuration, communication priority, and fault codes. Maintenance personnel can use the peripheral button group 502 to input connection channel configuration and priority adjustment commands to the control module 3 via the button circuit. When there is an abnormal wiring or communication interruption in the connection channel master or slave, the control module 3 triggers the indicator light drive circuit, causing the indicator lights of the corresponding connection channel in the indicator light group 503 on the surface of the housing 100 to turn on or off or flash, providing intuitive feedback on the fault location and helping maintenance personnel to quickly locate the fault. This enables the on-site personnel to quickly perform maintenance and status visualization on the intelligent connection devices.
[0050] In this embodiment: the base fixing module 6 includes a guide rail type mounting buckle 601 located on the back of the bottom of the outer shell 100. The guide rail type mounting buckle 601 includes a horizontal guide rail adapter buckle 6011 and a vertical guide rail adapter buckle 6012. The horizontal guide rail adapter buckle 6011 and the vertical guide rail adapter buckle 6012 are made of metal springs or plastic materials. The base fixing module 6 also includes a plurality of fixing mounting screw holes 602 opened on both sides of the bottom of the outer shell 100.
[0051] Specifically, when installing the intelligent connection device on different mounting surfaces such as the power distribution cabinet rails or walls, when the base fixing module 6 is installed on the rails, the maintenance personnel align the rail-type mounting clips 601 on the bottom back of the outer casing 100 with the standard 35mm rails, and use the elastic clips 6011 for the horizontal rail adapter clips 6011 or the vertical rail adapter clips 6012 to snap into the rails for quick mounting.
[0052] When fixed to the wall, the device is secured with screws through the mounting screw holes 602 on both sides of the bottom. When the device is subjected to stress due to frequent access of multiple master and slave devices, the guide rail type mounting buckle 601 cooperates with the mounting screw holes 602 to ensure that the device is stable and does not shake, ensuring the stable operation of the internal modules, and enabling the intelligent connection device to adapt to the multi-master and multi-slave communication needs in various installation scenarios.
[0053] In this embodiment, the wiring status of the host terminal block 201 and the slave terminal block 202 is displayed by the indicator light group 503 of the human-machine interface 5.
[0054] Specifically, during multi-channel wiring maintenance, the host connects to the host terminal block 201, and the slave connects to the slave terminal block 202. The control module 3 monitors the connection status of the terminal voltage and the path signal in real time. When the host and slave of the connection channel are properly connected and communicating, the control module 3 uses the indicator light drive circuit to make the indicator light group 503 of the human-machine interface 5 corresponding to the connection channel stay on or flash. When the wiring is loose or open, the indicator light goes out or flashes abnormally. This allows maintenance personnel to quickly know whether the master and slave wiring of the 8 connection channels is normal by checking the indicator light group 503 without having to check each terminal individually. This adapts to the needs of rapid wiring verification and fault diagnosis in multi-master and multi-slave scenarios, improving maintenance efficiency.
[0055] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0056] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A smart connection device supporting multiple masters and multiple slaves, characterized in that, include: A power module (1) used to provide AC / DC power to the device. Connection module (2) used to realize the connection between the host and the slave. The control module (3) is used to perform multi-master multi-slave connection scheduling and priority management functions. An isolation module (4) is used to prevent interference between the connection module (2) and the control module (3); Human-computer interaction interface (5) used to realize human-computer information interaction; Base fixing module (6) for fixing the device; The power module (1) includes a housing (100), the connection module (2) is installed on the outside of the housing (100), the control module (3) is installed inside the housing (100), the isolation module (4) is located inside the housing (100), the human-machine interface (5) is installed on the top of the housing (100), and the base fixing module (6) is installed on the bottom of the housing (100).
2. The intelligent connection device supporting multiple masters and multiple slaves according to claim 1, characterized in that, The outer casing (100) is made of metal or flame-retardant insulating material, and the outer casing (100) is also equipped with an AC / DC conversion circuit, which outputs two DC power supplies.
3. The intelligent connection device supporting multiple masters and multiple slaves according to claim 1, characterized in that, The connection module (2) includes a host terminal block (201) located on one side of the housing (100) and a slave terminal block (202) located on the other side of the housing (100). The host terminal block (201) contains at least 16 terminals corresponding to 8 connection channels. Each connection channel is adapted to 2 host terminals. The slave terminal block (202) contains several terminals corresponding to the 8 connection channels. Each connection channel is adapted to multiple slave terminals.
4. The intelligent connection device supporting multiple masters and multiple slaves according to claim 3, characterized in that, The control module (3) consists of 8 independent control sub-modules (301), each corresponding to 8 connection channels. Each control sub-module (301) integrates a microcontroller, a storage unit, and a communication interface. The communication interface is used to interact with the isolation module (4) and the human-machine interface (5) for data exchange.
5. The intelligent connection device supporting multiple masters and multiple slaves according to claim 3, characterized in that, The wiring status of the host terminal block (201) and the slave terminal block (202) is displayed by the indicator light group (503) provided on the human-machine interface (5).
6. The intelligent connection device supporting multiple masters and multiple slaves according to claim 1, characterized in that, The isolation module (4) is an isolation component (401), which is an opto-isolator or an electromagnetic isolator. The input end of the isolation component (401) is connected to the signal output end of the connection module (2) through a wire, and the output end is connected to the signal input end of the control module (3). The isolation component (401) cuts off the electrical interference path between the connection module (2) and the control module (3) through an optocoupler or isolation coil inside.
7. The intelligent connection device supporting multiple masters and multiple slaves according to claim 1, characterized in that, The human-machine interface (5) includes a liquid crystal display unit (501) installed on the top of the outer shell (100). The liquid crystal display unit (501) is connected to the display driver interface of the control module (3) via a ribbon cable. A button group (502) is also provided around the liquid crystal display unit (501). The button group (502) is connected to the button input interface of the control module (3) via a button circuit. The human-machine interface (5) also includes an indicator light group (503) distributed on the surface of the outer shell (100). The indicator light group (503) is electrically connected to the control module (3) via an indicator light driver circuit.
8. The intelligent connection device supporting multiple masters and multiple slaves according to claim 1, characterized in that, The base fixing module (6) includes a guide rail type mounting buckle (601) located on the back of the bottom of the outer shell (100). The guide rail type mounting buckle (601) includes a horizontal guide rail adapter buckle (6011) and a vertical guide rail adapter buckle (6012). The horizontal guide rail adapter buckle (6011) and the vertical guide rail adapter buckle (6012) are made of metal springs or plastic materials. The base fixing module (6) also includes a plurality of fixing mounting screw holes (602) opened on both sides of the bottom of the outer shell (100).