The front-end machine consists of a 8031 ​​single-chip microcomputer system with an RS-422 interface, which is placed near the control site. The communication controller is an interface board with a 8031 ​​microcontroller inserted in the IBM-PC/XT expansion slot, providing an intelligent channel for communication between the host and the front-end. The user only needs to send a simple command to the controller through the host without having to know the details of the communication, so that the front end machine can perform the corresponding action. The data sent or received by the controller each time is variable, but does not exceed 255 bytes. Error detection and error processing are performed for each communication to ensure the accuracy of data transmission. The host IBM - PC / XT is the initiator of the command and the controller of the system operation.
Figure 1-27 is a block diagram of the front-end machine. It is a 51 series microcontroller system with RS-422 serial interface. The number of channels for its input/output and A/D conversion is configured according to the needs of the actual application control system (such as the automatic detection line of the car), and is independent of communication. Figure 1-28 shows the schematic of the serial interface. The interface of each front-end machine and communication controller is differentially driven and received by MC3486 and MC3487. The serial bus consists of a pair of twisted pairs DATA+ and DATA-. The end of the twisted pair has a boosting resistor that causes the line to be in a logic 1 state when idle. When the logic o (TxD=O) is transmitted, the line is in the 0 state. This differential drive and receive bus meets the RS-422 standard in terms of electrical characteristics. Compared to RS-232, this single-ended drive bus has the advantages of strong anti-interference ability, high data transmission rate and long distance.
The block diagram of the controller is shown in Figure 1-29. The 8031 ​​exchanges data with each front-end machine and host through the serial interface and the parallel interface. The schematic diagram of the parallel interface is shown in Figure 1-30. The data exchange between the controller and IBM-PC/XT is implemented by query. 8255A works in port A mode 2 (bidirectional bus I/O). When the controller outputs data to IBM-PC/XT, the WR signal is valid to write data to port A, which makes PC7 (OBFA)-O (initial state OBFA). =1); IBM - PC/XT reads the state of 8212III and knows that OBFA=O, then reads 8212 I can read the A port data; at the same time, the 8212 I INT signal returns the OBFA to the initial state. When IBM-PC/XT sends data to the controller, it writes the data to 8212II with the output command; meanwhile, the 8212II INT signal is valid, causing PC4 (STBA) to generate a strobe signal; this signal sets PC5 (IBFA) to be valid ( That is, IBFA =1, initial state IBFA=0), 8031 ​​reads the state of C port of 8255A and learns that IBFA =1. Read the A port to read the data into the controller. The parallel port address is partially decoded, the addresses of 8212 I and 8212II are 02EOH, and the address of 8212III is 02EIH.
Here comes the first GEEKVAPE DNA 100C pod mod!
With Geekvape Z100C DNA Kit in hands, the perfect flavor never ends.
DNA 100C Chip, a flavor DIY master with Boost & Replay.
Form-switchable 100W mod with 3A Type-C charging.
New P0.15 XM coils with innovative mesh design, are stronger, more robust, and last 2 times longer than ordinary coils.
greekvape z series vape box,greekvape z series vape mod kit,greekvape z series vape pen,greekvape z series vape device,greekvape z series vape kit
Ningbo Autrends International Trade Co.,Ltd. , https://www.supermosvape.com