FOXBORO FBM243 P0914TK通信模塊
鏈中的最后一個(gè)PQM和主計(jì)算機(jī)需要端接電阻器和端接電容器，以確保負(fù)載的正確電氣匹配并防止通信錯(cuò)誤。在所有PQM上使用端接電阻器會(huì)降低通信網(wǎng)絡(luò)的負(fù)載，而在末端省略它們可能會(huì)導(dǎo)致反射，從而導(dǎo)致通信錯(cuò)誤。外部安裝120Ω?瓦終端電阻器和1 nF電容器。盡管這些值的任何標(biāo)準(zhǔn)電阻器和電容器都是合適的，但這些組件也可以作為組合終端網(wǎng)絡(luò)從GE Multilin訂購(gòu)。每個(gè)通信鏈路必須只有一臺(tái)計(jì)算機(jī)（PLC或DCS）發(fā)出命令，稱為主機(jī)。主設(shè)備應(yīng)位于中央，可用于查看每個(gè)PQM（稱為從設(shè)備）的實(shí)際值和設(shè)定值。使用Modbus RTU協(xié)議的其他GE Multilin繼電器或設(shè)備可以連接到通信鏈路。
The last PQM in the chain and the master computer require a terminating resistor and terminating capacitor to ensure proper electrical matching of the loads and prevent communication errors. Using terminating resistors on all the PQMs would load down the communication network while omitting them at the ends could cause reflections resulting in communication errors. Install the 120 Ω, ? watt terminating resistor and 1 nF capacitor externally. Although any standard resistor and capacitor of these values are suitable, these components can also be ordered from GE Multilin as a combined terminating network. Each communication link must have only one computer (PLC or DCS) issuing commands called the master. The master should be centrally located and can be used to view actual values and setpoints from each PQM called the slave device. Other GE Multilin relays or devices using the Modbus RTU protocol can be connected to the communication link.
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