基于ethernetip的controllogix系列plc的接口畢業(yè)論文外文翻譯-其他專業(yè)-資料下載頁
【導(dǎo)讀】類型：如以太網(wǎng)、ControlNet、DeviceNet、RS-232等等。ControlLogix以太網(wǎng)連接模塊?！?756-ENET”使用了EtherNet/IP、ControlNet等協(xié)議，并采用了專業(yè)的服務(wù)代碼封裝。于以太網(wǎng)協(xié)議包中。針對“實(shí)驗(yàn)性物理和工業(yè)控制系統(tǒng)”開發(fā)的驅(qū)動(dòng)程序使用了。EtherNet/IP協(xié)議，從而使得控制器可以運(yùn)行vxWorksRTOS、Win32和Unix/Linux的測。現(xiàn)在來分析一下這個(gè)接口的特點(diǎn)和使用場合。散裂中子源項(xiàng)目的幾個(gè)子系統(tǒng)使用了A-B公司的ControlLogix系列PLC。有了輸入輸出控制器，Unix或Win32系統(tǒng)的計(jì)算機(jī)和所有裝有以太網(wǎng)連。在現(xiàn)有的綜合布線、網(wǎng)絡(luò)硬件、配置和維護(hù)等技術(shù)知識(shí)的支持下，該產(chǎn)品完全可以。似，采用了從物理層到應(yīng)用層分層方式。版本引入了數(shù)據(jù)包的TCP/IP封。們定義了目標(biāo)對象控制和信息協(xié)議，此協(xié)議被列為ControlNet協(xié)議的一部分。ControlNet傳送層，協(xié)議區(qū)別“無關(guān)聯(lián)”和“關(guān)聯(lián)”CIP信息。但都可以通過默認(rèn)的TCP協(xié)議進(jìn)行連接。ControlLogix系列PLC使用ControlNet總線來聯(lián)接本地I/O板卡作為平臺(tái)，一周期內(nèi)每個(gè)PLC將處理所有讀寫請求。以處理的PLC數(shù)據(jù)類型包括BOOL、SINT、INT、DINT和REAL。也可以在運(yùn)行時(shí)改變記錄
【正文】 C and a Linux file server were connected to the same hub. Network utilization was generally below 2%. On average, 11 milliseconds are required to transfer a single tag, be it a scalar REAL, BOOL or DINT, an array of 15 REAL or 352 BOOL values. Since the EPICS driver bines multiple requests up to the PLC buffer limit, about 15 tags, each with a 15character name, can be read in one transfer of about 20 ms while the separate transfers would require more than 160 ms. In an attempt to simulate a mon application, an IOC was configured with 352 binary input records, scanning the elements of a BOOL array at 10Hz, and 120 analog input records, scanning three 40element REAL arrays at 2 Hz. Since Ether is not deterministic, these transfer rates vary over time due to collisions on the work, resulting in a transfer time histogram as shown in Fig. 1. Figure 1: Transfer times sampled over 3 days. On average, the whole BOOL array transfer was handled in 15ms, all REAL arrays were transferred in 25ms, so that the records could easily be updated at the chosen scan rate. In these measurements, the “System Overhead Time Slice of the PLC was set to 10%. After increasing it to 50% and connecting the CPU and PLC to a work switch, the average times for a single tag are reduced to 7ms. 7 CONCLUSION It is possible to use the published EtherNet/IP specification together with the openly available AllenBradley extensions to read and write tags on a ControlLogix system. The EPICS support is convenient to use. The record configuration can be changed at runtime。 transfers are automatically bined up to the PLC buffer limit. In contrast to other protocols, there is no need to define the affected tags as “produced” or “consumed”, nor does it require a workwide assessment of timing values for scheduling transfers as the original ControlNet did. Due to the nature of Ether, the exact transfer time varies. A switched work topology will help minimize variations. To reach the required throughput, values of interest should be arranged in arrays. To keep the ladder logic readable, intelligible tag names can be used to alias the meaningless transfer array elements. The published CIP service codes do not allow browsing of PLC tag names and type information, which would allow an even more userfriendly EPICS driver. With explicit messaging, each tag transfer is a roundtrip request. The tested version of the 1756ENET module does not support implicit messaging. Ideally the IOC could subscribe to the tags of interest and from then on receive asynchronous notification of changes or at least periodic updates, eliminating the need to poll. The current implementation, however, does already allow for a successful integration of ControlLogix systems into an EPICS environment REFERENCES [1] Rockwell Automation,“ControlLogix Selection Guide”,Publication 1756SG001AUSP from July 2021. [2] ControlNet International, Ltd, “ControlNet Specifications Release , Errata 2”, 2021. [3] Rockwell Automation, “Logix5000 Data Access”, from. , March 2021. [4] John K Munro, Jr., John C. Cleaves, KayUwe Kasemir, Ernest Williams, Delphy Nypaver, David Meyer, “Use of EPICS for HighLevel Controls of the SNS Conventional Facilities”, ICALEPCS 2021, San Jose, November 2021. [5] R. Stevens, “UNIX Network Programming”, Prentice Hall, 1990. [6] Open DeviceNet Vendor Assoc., “EtherNet/IP Specification, Preliminary Release 8”, March 2021.
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