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Daveinarmstrong

Lost communication PC to PLC. Need help

17 posts in this topic

I have a FX2N 16MR PLC with a FX2N-232-BD adapter board. the setup has worked fine for many years. Yesterday, the PC has not been able to upload values. Is it possible that the FX2N-232-BD adapter board parameters have been wiped out? How do i re-establish the parameters. I am able to connect with my laptop to the PLC using Gx developer and an 09 cable. The PC serial cable did come part way unplugged and 2 conductors were not working but i have since plugged it back in and still no communication. Thanks in advance for your help. Edited by Daveinarmstrong

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Reset the BD card by ensuring that D8120 = 0 and that it will not get overwrited anywhere (D8120 must be 0 at boot up)

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set to 0 and still no communication.

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Is it still 0 when you monitor Your program from the data monitor? It is important that it is set to 0, and then booted without setting any other value into it (the card is initialized during boot). The PC cable should be crossed (not straight)!

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set it to 0 using M8000 DMOV K0 D8120

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D8120 came up as 0 when i rebooted the PLC. I then wrote the plc software to the plc including the parameters and then restarted the PLC and still no communication. it shows comm error in PLC diagnostics. Edited by Daveinarmstrong

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What software are you trying to connect to the BD card? You say you have a computer, but what software/driver is trying to communicate with the PLC?

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i am using Lobo machine corporation software on the PC to download user data to the PLC .

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You're absolutely sure that the software uses the CPU protocol, and not the MC protocol (which requires different settings on the BD card....). You can test this by using the Programming port/cable on the PLC and let the software communicate through that just for a check.... You can also cross-test this by using the BD card for Programming. When D8120 = 0, it is Programming protocol, hence Your Programming software should support Programming through BD...

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i have attached a screen shotMy link of the parameters that came with the original PLC program. i'll test the software using my laptop if i can through the programming port. Edited by Daveinarmstrong

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Well, since the Protocol is set to Non-Procedural it's Clear that the computer software is using something else, and there must be a program location where there's a pre-programmed protocol in the PLC. When Non-Procedural is set, you must use the PLC itself to implement any kind of protocol you want. The computer is not using any standard Mitsu protocol, hence someone has programmed a custom protocol in the PLC that interacts With the computer software. You should use the original settings.

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I don't see the D8120 location in the ladder program, accept for where i moved 0 to it. Is that what i should be looking for? something being moved to the D8120?

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It may also be set in PLC parameters, if you don't see program code setting a number to D8120. Check the last tabs of the PLC parameters.

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I see the last tab cointaining the parameters. This FX2N PLC uses a EEPROM. should i be removing it to write the parameters to the PLC? or is it ok to store the parameters on the EEPROM. The PLC is asking for a keyword when i try to write the parameters to the PLC with EEPROM removed. i was going to disconnect the battery to wipe out the password. just wondering if there are other hidden parameters that i may lose. i have the ladder program and the Comm parameters backed up and the user data. Edited by Daveinarmstrong

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DO NOT REMOVE THE EEPROM WITH THE POWER ON! When using FX2N, if it powers up with the EEPROM installed, that is the program it runs, the one on the memory module. Any upload or download will be to the memory module. When powered up without a memory module, it uses the program in its internal memory. Any download will be to the PLC memory. The parameters must be stored where the program is.

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in my ladder program when M27 is on, it activates this [FROM K0 K29 D206 K1] and D206 shows the number 293. How do i find out which error this is? i have the PLC on my desk connected to GX developer and when i go into PLC Diagnostics it displays PLC/PP comm err and also Link error. there are no other numbers or descriptions. i see that link error is a serial communications error but is there a way to get the cause of the communication error?

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Buffer 29 in all FX modules is not an error code, it's a module identification code. Each type of module has a different code. That link of code is verifying that the right type of module is found as special function module 0. This is code to communicate to a special function module on the right side of the PLC. It has absolutely nothing to do with your communication problem on the BD board.

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