Emerson CE4003S2B3 Controller, Shanghai Sijian Intelligent Technology Co., Ltd. is engaged in technical development, technical consultation, technical transfer in the fields of intelligent technology, information technology, and automation technology, as well as the sales of electrical equipment, automation equipment, electronic products, communication products, and electromechanical products. Industrial automation products include: PLC, DCS, sensors, frequency converters, encoders, relays, servo drives, soft starters, and touch screens. The brands involved in the products are: Eurotherm, Schneider, Siemens, ABB, SICK, P+F, E+H, Yokogawa, Yamakawa, Mitsubishi, Emerson, Honeywell, FANUC, GE, Eaton Electrical. The CT RS-485 standard is also a serial interface standard with a balanced transmission method. It is compatible with RS-422A and extends the functionality of RS-422A.
Electrical characteristics of RS-485: Logic "1" is represented by a voltage difference between the two wires of +(2-6)V; logic "0" is represented by a voltage difference of -(2-6)V. The interface signal level is lower than that of RS-232C, making it less likely to damage the interface circuit chips, and this level is compatible with TTL levels, allowing easy connection with TTL circuits. The data transmission rate is 10Mbps. The RS-485 interface uses a combination of balanced drivers and differential receivers, enhancing common-mode rejection capability, meaning it has good anti-interference performance. The standard transmission distance for the RS-485 interface is 4000 feet, but it can actually reach 3000 meters. The RS-485 interface allows up to 128 transceivers to be connected on the bus, providing multi-station capability, enabling users to establish a device network. Due to its excellent anti-interference performance, long transmission distance, and multi-station capability, the RS-485 interface has become a preferred serial interface.
Emerson CE4003S2B3 Controller, In this system, the communication between the upper computer and the lower computer utilizes the RS485 and RS232C communication standards from the above standards. The computer has a standard RS232C interface, while the PLC has a standard RS485 interface. The two are connected via a cable and an RS485/RS232C conversion module.
In this system, the information management and operation of the upper computer run on the Windows 2000/NT operating system, and the serial communication program is developed using Delphi 6.0, a rapid development tool from Inprise. The PPI communication protocol is specifically developed for the S7-200 series PLCs. Physically, it uses RS485 signal levels, and the PLC defaults to this mode. Using the PPI method for PLC programming and debugging requires only a programming (PI) cable for hardware connection. Software programming is conducted in a Chinese environment with an internal system protocol. Designers only need to set parameters through the software; data exchange does not require consideration, as data transmission can be achieved using the NETR and NETW instructions.