Automatic matching system and method for terminal resistors of PLC expansion bus
A technology for expanding bus and terminal resistance, which is used in general control systems, control/regulation systems, electrical program control, etc.
Active Publication Date: 2015-12-30
深圳市合信自动化技术有限公司
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Problems solved by technology
However, in the prior art, in a system in which PLCs and expansion modules are cascaded, it is necessary to manually determine which expansion module is the last expansion module, and manually connect the terminal resistor set at the expansion module.
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[0021] Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.
[0022] Such as figure 1 As shown in FIG. 1 , it shows a schematic structural diagram of an embodiment of a terminal resistance automatic matching system of a PLC expansion bus provided by the present invention. In this embodiment, the terminal resistance automatic matching system of the PLC expansion bus includes PLC1 and multiple expansion modules 2, and the expansion bus is used for cascade connection between PLC1 and multiple expansion modules 2; wherein, in one embodiment, the The expansion bus adopts the MLVDS bus, which belongs to the half-duplex communication of the bus topology. The expansion buses mentioned in the following are all described as the MLVDS expansion bus. It can be understood that in other embodiments, other type of bus. The expansion modules 2 are cascaded. Each expansion module is an independent entity and has no priority, bu...
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The invention discloses an automatic matching system for terminal resistors of a PLC expansion bus. The system comprises a PLC and multiple expansion modules, and the PLC and the multiple expansion modules form a bus topolopy structure through expansion bus concatenation, wherein each expansion module is provided with a forward direction communication interface and a backward direction communication interface, each forward direction communication interface is provided with a first switch, each backward direction communication interface is internally provided with a second switch, and each first switch and the corresponding second switch are connected in parallel and connect a terminal resistor to the expansion bus; the first switches and the second switches are all normally-closed switches, when being plugged into a certain forward direction communication interface, a cable abuts against the corresponding first switch and gets the corresponding first switch to be switched off, and when being plugged into a certain backward direction communication interface, a cable abuts against the corresponding second switch and gets the corresponding second switch to be switched off. The invention discloses a corresponding automatic matching method for the terminal resistors of the PLC expansion bus. By means of the technical scheme of the automatic matching system and method for the terminal resistors of the PLC expansion bus, the terminal resistors can be matched automatically and quickly.
Description
technical field [0001] The invention relates to the field of programmable logic controllers (ProgrammableLogicController, PLC), in particular to a terminal resistance automatic matching system and method of a PLC expansion bus. Background technique [0002] In the prior art, PLC is to expand I / O (Input / Output, input or output) points or functions. Generally, various I / O modules or functional modules need to be connected through an expansion bus to form a PLC control system. The expansion bus communicates with I / O modules or function modules. [0003] Existing PLCs and expansion modules use expansion buses such as serial peripheral interface (serial peripheral interface, SPI) or controller area network bus (ControllerAreaNetwork, CAN) for connection and communication. In specific applications, between PLC and expansion modules Before communication, it is necessary to complete the matching process of the terminal resistance. Among them, the terminal resistance is the resista...
Claims
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IPC IPC(8): G05B19/05
CPCG05B19/052G05B2219/1109
Inventor 王精
Owner 深圳市合信自动化技术有限公司