140XCP51000 Virtual Module

140XCP51000 Virtual Module

The communication between the 140XCP51000 series PLC and the computer is based on the RS-232 standard, which has a fixed transmission rate of 9600 bps and an even parity bit. Data is sent and received in frames. A multi-character frame consists of five parts as shown in the force, which and the parity value is the command code ETX between the character of the ASCII code (hexadecimal number) is added to obtain the lowest two digits of the resulting sum. STX and ETX respectively, the character frame that the beginning of the beginning and end of the mark.

Communication between the 140XCP51000 Series and the computer is based on an initial command from the host computer to which the PLC responds. There are a total of four commands, 0, 1, 7, and 8, and the host computer realizes reading, writing, and force setting of the PLC. Through ENQ, ACK and NAK, the host computer coordinates the communication response to the PLC.

140XCP51000 can read, write and force ON/OFF operations to each soft device in the PLC. All switching inputs and outputs of the FX2 series PLC and each software device are transparent to the computer, except when the PLC’s timer and counter set values use constants and the data in the file registers. The format of the multi-character frame for operation is shown in Fig. 3. However, there are differences in the “multiple character” items for different operations. For example, the computer reads the PLC’s soft devices Y20 to Y37, checks the device address table for 00A2, and reads 2 bytes of data.