Ask for help with S7 200 communication questions

The upper computer 232 communicates with the PLC, and there are two methods.

One is to use the ordinary 232 485 level converter, connect the converter to the serial port of the PC, use the screen cable, and connect the 485 end A, B, and GND to the PLC and 5 respectively (please check the information and then connect), so that it can be communicated.

If you use the original 232 PPI cable (the kind with DIP switch), the PPI (485) side must be connected to the PLC, and a pair of 232 485 converters can be used at the 232 end, first convert 232 to 485, and then turn 485 to 232 at the other end and connect it to the PC. Because the conversion circuit in the programming cable has a CPU, which draws power from the PLC port when working, it cannot communicate if it is only drawn out.

In addition, the communication error you are referring to, is it a communication error in the programming software or the configuration software? If it is a configuration software communication, then the communication port definition such as station address, baud rate, start and stop bits, etc., must be set up in the PLC; In the case of programming software, it will automatically search for devices in the network, as long as the communication method (e.g. PPI or MPI) is selected as PC PPI, because the programming cable is adaptive and the details do not need to be defined.

I can communicate with other S7-200PLCs normally with the same settings, does that mean that the settings are okay? As for the hardware connection, it is possible, but why can it communicate with the touch screen? Or do you want to ask?

Communication timeout error, check the port number, network address, baud rate and cable PLC model is 226, you can do without memory card.

There is no memory card.

If you can't connect, see if you made an error when setting up the network connection, and if not, then see if it's a hardware connection problem!

That's right. I haven't encountered it, but I've done it: I made a PLC extension cable, the extension cable from the PLC communication port all the way to the computer on the console, and then connected with the computer serial port through a special PC PPI cable, my extension cable is about 40 meters, but there is no problem with communication.

How can it be extended to 20 meters? Generally, Siemens standards are 5 meters, extended to more than 5 meters after the insurance, it is recommended that you take the modbus rtu, that is, the 200plc interface to take the modbus, to ensure that it can reach 400 meters. Or you just buy a 5611 card, so that you can reach 50 meters.

I haven't modified it, I'm new to this set of equipment, I don't know if I've modified it before! How do I get it?

Check whether the PG interface settings of the PC match the communication cable.

Check whether the communication cable drive is normal.

The above 2 normal may be damaged communication lines or PLC communication ports.

There is also a possibility that when the 200 communication port is set to only communicate with the port, only the PLC mode switch can be set to STOP to communicate normally.

Another thing is to check if there is any problem with your computer interface, such as insufficient power supply.

300 access to a 200mpi network can also be a dp network, then we have to configure the gsd file, the number of bytes sent and received to define.