1747-L553 Graphic Display Programmes

The 1747-L553 is designed with two forms (Form1 and Form2). Form1 is the main interface and Form2 is the waveform display interface. An MSComm control, a timer control (Timer1) and two button controls (Command1 and Command2) are designed in Form1. Command1 is the start button, i.e. when pressed, it starts to communicate with PLC and read the data therein, Command2 is the display button, i.e. when pressed, it calls Form2 and displays the waveform curves of each running quantity. A picture box control (Picture1) is designed in Form2 to display graphics.

1747-L553 sets the Interval property of Timer1 to be equal to 500, the InputMode property of MSComm to be binary, and the RThreshold property to be equal to 5010. The timer sends the transmit command every 500 milliseconds, and when it is sent for the 26th time, it turns off the timer, and at that time the receive buffer will receive 5010 bytes of of data in the receive buffer and triggers the OnComm event of MSComm. In the OnComm event subroutine, the data in the receive buffer is sequentially allocated to the global arrays U_data, If_data, P_data, Q_data, and Ug_data, and then a percentage value is calculated based on the rated value of each run. The first 350 bytes of each array need to be adjusted according to the pointer Index by moving the data in the array subscript range Index to 349 to the front and the data in the subscript range 1 to Index-1 to the back.

1747-L553 Write the graphic display program in the loading event Form_Load of the form Form2. First, set a custom coordinate system in the picture box control Picture1. Set the value of ScaleMode property equal to 3, i.e. in pixels. Then draw the axes under this coordinate system. x-axis is in seconds, the time interval between two points on the curve is 40 milliseconds, which is converted into pixels equal to 1.47. y-axis is in percentage, each unit scale is converted into pixels equal to 2.1. finally, according to the arrays of U_data, If_data, P_data, Q_data, and Ug_data respectively, we will draw a waveform graph of the corresponding runtime quantities. Waveform diagram.