M1923

MrPLC Member
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About M1923

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  • Country China
  1. D720S, RS485 comms

    There is no 4 wire RS485, it is RS422 which has 4 wires, full duplex configuration. 2XRS485 = RS422 By the way, is there anyone knowing the electrical property of network cable? Is it similar to RS485? The network cable has several pairs twisted wires whose speed is up to 100M, but RS485's can only reach to several M, I don't know why, anyone can help?
  2. How to connect GOT: F940 and PC

    Configuration software may be needed on your PC,if you don't want to write the communication program yourself.
  3. FX3U Analog Output Problem

    Latched data register is the register backup by battery or big electric capacitor after power failure. File registers will be backup by program memory, you can choose to backup the file registers or not by using command BMOV when their value have been changed. I think this the biggest difference. Hope this help.
  4. Thanks, Mr Bryll, it will be very helpful. I find the problem at last, my PLC goes wrong. I try another one, then the communication back to normal. There is no surprise, this sort of things happen in China. Thank you for all your concern, guys.
  5. I set the communication format by using parameters, instead of writing data to the register.These two way which I have already tried, unfortunately, don't work at all. Actually, it is the D8120, not D8400 or D8401, I should deal with when use RS(not RS2) instruction. Yes, I am going to use Modbus RTU, it seems to be used widely in inverter, printer,and so on.
  6. I use GX Works2 1.77F. Now, I am going to find another PLC to try it. By the way, what protocol did you use? Modbus?
  7. Sorry,Mr Kaare_t, for replying to you so late. Today,I do what you advice. I connect PLC to my computer through a RS485-USB converter, my software on computer is VB6. The program(shows below) written in VB6 will display "ok" characters on testbox when it receives any data from PLC . Unfortunately, it doesn't work, when PLC sends data to computer, nothing is displayed on the textbox. but oddly, PLC can receive data send from computer, and its register value can be changed, that is what I have observed. It is the RS instruction(none protocol) been used on the PLC side, when I change it to computer link protocol, the communication works normally again. I am going to be mad about the RS instruction... ...
  8. Of course, I did. Before ask this question, I have read the communication manual for many times, just can not find a solution.
  9. Confused about sink and source input

    Thank you for your helpful answer, Mr Panic , it makes the question more clearer.
  10. Hi everyone: My hardware : AVR(Atmega16A) + Maxim 485 IC ------------RS-485-BD + FX 1N. I have a problem when I use AVR microcontroller to communicate with PLC. When the protocol is computer link, they work perfectly, AVR can read or write data from/to PLC. But when I use RS instruction(non-protocol) to communicate, things become wrong, PLC can't receive data from AVR and the RD+ LED on RS-485-BD dosen't flash at all. When PLC sent data to AVR, the SD+ LED flash, but AVR receive no data. I am sure the character format and baudrate are right, my PLC ladder show below. Can anyone tell me why PLC go wrong when using RS instruction. I suppose my PLC got some problems , after all , it is second-hand. But I don't have another one in hand to check that . thanks in advance.
  11. confused about FX-2DA ladder

    Yes, and if you want to use Ch2, you should write data to D1 too.
  12. Confused about sink and source input

    I know exactly how input circuit works ,just confused about the definition of sinking and sourcing . Obviously, the two pictures show opposite definition.
  13. Confused about sink and source input

    Thanks for your answer , Mr Inntele.
  14. confused about FX-2DA ladder

    I've read, but I am confused about this
  15. confused about FX-2DA ladder

    You should have a look at the manual.