(1) Program preparation. Check that the connection between the PLC and the computer is correct, that the RS232C port of the computer is connected to the PLC and that the range line and converter are connected: keep the PLC in the “off” state; There is a power supply on the computer and PLC.
(2) Programming operation.
1 Open the GX Developer programming software, create a new project and name it.
(2) Use the ladder diagram programming method to edit and save the ladder diagram program as shown in Figure 1.
(3) Transmission of the program.
Programming. The edited program is written into PLC user memory and checked.
2 Program reading. Programs In the PLC user memory are Read into the computer by the [Read In] operation and then checked.
(3) Program check. In the process of checking the above programs, only when the programs on both ends of the computer are relatively correct, can the program be considered to be correctly transmitted, otherwise the cause should be identified and re-transmitted.
2. Run the operation
After the program is transferred to the PLC user memory, the program can be run in the following manner.
1 Connect the input/output of the PLC to the input signal of the component according to the ladder diagram program. The input/output numbers and descriptions of PLC are shown in Table 1.
(2) Open the PLC operating switch, and the running light on the PLC panel indicates that the program has been put into operation.
1794-OE12 The performance parameter control procedure should be combined with the control procedure to operate the input signal and observe the change of the input/output indicator light under different input states. If the status of the output indicator is consistent with the program control requirements, it indicates that the program is running normally.
1. Common fault phenomena
When the PLC’s rs-485 port is connected to the computer through a non-isolated pc/ppi cable, the connection between the plc and the plc, or the communication between the plc and the inverter, the touch screen, etc., the communication port is damaged. More common damages are as follows:
(1) R1 or R2 is burnt out, Z1, Z2 and SN75176 are intact. This is because the transient interference current through R1 or R2, bridge rectifier, Z1 or Z1 to the ground is large, Z1 and Z2 can withstand the impact of *10A current, the current generated by R1 or R2 transient power is 102*10=1000W, of course, it will burn out.
(2) sn75176 damage, R1, R2, Z1, Z2 are in good condition. This may be due to static shock or transient overvoltage speed faster than Z1, Z2 operation speed, static electricity everywhere, only the human mode will produce ±15 kV static electricity.
(3) z1 or z2, sn75176 damaged, r1 and r2 intact. This may be due to high voltage and low current transient interference voltage breakdown z1 or z2 and sn75176. Due to the small current and short generation time, r1 and r2 do not burn.