PLC in Figure 1 collects the data o

PLC in Figure 1 collects the data of 20 pieces of smart meters with master-slave scanning communication protocol mode, each communication process is initiated by the master station, responded by the slave station to transmit information back, then a communication is completed. All kinds of instruction code and data in AI instrument are indicated by hexadecimal data formats. There are two standard communication instructions only, one is read instruction, the other is write instruction, through optimization design to AI instrument software communication instruction. It makes the PLC software writing easy, and can complete instrument operation 100%. The read instruction format for the AI instrumentation is shown in Table 3, and the write instruction format is shown in Table 4.