【正文】 , opens with the title S7_Pro1 . 2. Doubleclick the OB1 icon in the righthand part of the window. The editor for editing the OB 1 block opens. 3. In the View menu, select LAD to change to the ladder logic programming language. At the bottom of the lefthand window, a current path is displayed in work 1. 4. Carefully click on the horizontal line representing the current path. The line is highlighted. 5. On the toolbar, click twice on the || icon (normallyopen contact) and then once on the –( ) icon (coil). The icons are inserted into the current path. 6. Click on the red question mark for the lefthand normally open contact in the current path. The normallyopen contact is highlighted and the question mark is replaced with a text input box containing the cursor. 7. Enter and press Return. The lefthand normallyopen contact is now called . 8. Label the right button in the same way with and the coil with . 9. Close the editor and click Yes when you are prompted to save. The editor is closed and OB 1 is saved. 5. Step: Configuring hardware Procedure 1. In SIMATIC Manager, click on SIMATIC 300 Station in the lefthand part of the window. The Hardware and CPU 313C icons appear in the righthand part of the window. 2. Doubleclick the Hardware icon in the righthand part of the window. The editor for editing the hardware opens. 3. If the catalog is not shown in the right section of the window, you can activate it by selecting Catalog in the View menu. 4. Expand SIMATIC 300 and CPU300 until you see CPU 313C. 5. Insert the CPU 313C by dragging it to slot 2 (top or bottom lefthand window). 6. Check that the order number displayed for slot 2 in the lower lefthand part of the window matches the order number of your CPU. You may need to expand the width of the order number column to see the entire number. If it does: Skip to the next step. If it does not: Expand CPU300 in the catalog until you see CPU 313C and replace the CPU in slot 2 by dragging the CPU with the correct order number from the catalog. 7. Perform steps 3 and 4 for the power supply module PS 307 too. You insert the PS 307 in slot 1. 8. Go to the Station menu and select Save and pile. The hardware configuration is piled and saved. 9. Close the editor. The editor is closed. 6. Step: Trial run Procedure 1. Use the SIMATIC 300 station and CPU 313C to browse to the S7 program. In SIMATIC Manager click on Blocks in the righthand part of the window. Blocks will now be highlighted. 2. Select Download from the PLC menu to transfer the program and hardware configuration to the CPU. Confirm all windows with Yes. The program and configuration are downloaded from the programming device to the CPU. The program is now stored on the Micro Memory Card (in the load memory), where it is unaffected by power failures and resets. 3. Set the CPU39。 It achieves the purpose of energy saving. FURTHER MODIFICATION This JSSP1 model was suitable for single pump water supply system. When the flowrate is little, the pressure can be much reduced. For example, Hp* varies from 1 to Hp* which is less than 1 (Hp* 1). It is able to save much energy. From this working principle, it was modified to suit a large scale multiple pumping water supply system. A new model of JS5P2 was then developed. Fig. 3 shows a block diagram of a variable frequency constant pressure system consisting of 3 same capacity pumps. It was modified from the JSSP1 model. It is designed for multi pumps water supply system which programmable logic control (PLC) is involved such that the number of hydraulic motors in operation can be determined by the flow rate. The rest of motors are in standby mode and the energy saving can be realized. From Fig. 3, the system was posed of pressure sensor (PS), pressure amplifier (A), pressure regulator (AP), signal identifier (AI), programmable logic control (PLC), and frequency regulator. The main feature of this system is that one set of variable frequency regulator is in use to control one hydraulic motor. The rest is idling at starting. If the water flow is within the preset range. This motor is running according its characteristic curve. When the flow rate is increased, The second motor will be smoothly started. The preset value of pressure in pipes can be maintained. There are three values for operating these motors, %, % and %. In brief, the first pump motor will work if the flow rate falls within % of operation. The operating region is within curves 1 and 4 in the Fig. 4. When the flow rate increases, beyond %, frequency regulator keeps the output frequency at 50 Hz, PLC will control of onoff state of the motors such that the first pump motor is supplied by the mains. The speed of the first pump motor runs at rated speed. The frequency regulator also set the second pump motor in standby mode. The operating region of the second motor is within curves 2 and 5 in the F