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Kinectix

FX3U and FX3U-232-BD not sending after stop cycle

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Hi, I have FX3U PLC and FX3U-232-BD connected to it. I use the "Practical Program Example (RS Instruction)" from manual "FX User's Manual Data Communication Edition" I've used the PLC parameter GUI tool to setup the parameters. Now the problem is that sending data does not work anymore after I stop the PLC and put it in RUN again ( the same happens with power off and on again). The way I know that data is not sent is that M8122 remains set ( and ofcourse nothing is received on the other end). However what helps is the following procedure: 1. Change PLC parameter protocol to: Non-procedural 2. Write to PLC, parameter only 3. Change PLC parameter protocol back to: Dedicated protocol 4. Write to PLC, paratmers only Now the sending works again but this approach is not usable in real life because there is no computer near PLC. Edit: image of PLC parameters: Am I doing something wrong? Is the PLC parameter data stored in volatile RAM? Edited by Kinectix

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Are you going to use the dedicated protocol or no protocol for the communication? In the ladder, did you set up the communication settings there in addition to the GUI interface (so that one of them will overwrite the other)? Remember that when using BD/ADP cards the PLC needs to be hard reset (power OFF/ON) for the settings to take place, so when changing any parameters in the cards always do a hard reset to be sure.

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Hi, I got it working. I am communicating with measurement instrument via COM port (only Tx, Rx, and GND signals are used). From the manual I figured that I need to use Non-Protocol communication (using RS command) which implies setting D8120 to 0x0881 according to manual. And yes, the bit b14 must be zero (meaning Non-Procedural for protocol in PLC Parameter settings). However the 0x0881 setting causes the PLC not to send anything. Using the PLC parameter settings and not direct settign from program (8N1 9600, Non-procedural, Regular RS232C, Form1) and reading the value back from program gives D8120 value of 0x0081. Closer inspection shows that this means the bits b11 and b10 are 0 and 0 which by manual means it gets set to RS485/482 mode. I think theres' an error in manual for this because surely I am using RS232 and it works. Some observations: changes to D8120 take effect immediately when changed in sequential program itself (though RS must be toggled active->passive->active) RUN-STOP-RUN does not change D8120 value ( remains same ) Power cycling does not change D8120 value ( remains same ) Maybe it helps someone. Edited by Kinectix

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Hi Kinectix, I think I'm having the same problem... PLC receives the messages but doesn't send the response. I didn't understand quite well how you solved your problem... Are you using the RS485 software setup for a RS232 communication? What programming software are you using? GX or GX IEC? How you make to write the parameters only? Thank you in advance!

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Hello Guardian, The development software I'm using is GX Developer-FX Version 8.25B. There are two methods to use. Either write the configuration data in your program (ladder, etc) or use the Parameter->PLC parameter window. I prefer the first method as it is more compact and also because there seems to be error in parameter setting window (see my previous post) For my setup please see the attached images. With X6 I load the config and with X10 I tell the program to send the data. M4 does the real sending. If you watch the hex 0x0081 as binary and look up the D8210 from datasheet then you will see what each bit means and how it will get set.

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