Need help.. MELSOFT connect failed!

[Gunboy 0]

Hi all, I recently try hard to establish the RS232 communication between plc and pc via C++ as i not so familiar to those communication protocol. And the worse case is, after i write in D8120 (what i guess it's the reason), i cant even connect the FX3u plc via MELSOFT anymore?! So now i not only cant download program into plc but i like cant do anything more. Anyone can help me on this? Or is it anyway to hardware reset the plc so that i can write in program to plc again. Million thanks.

[Gambit 331]

Don't you have a SC09 programming cable for the CPU port? Edited 14 Feb 2012 by Gambit

[Gunboy 0]

No, i dont use that, i am doing programming communication via 232BD all the while. Is it any other way to solve this? One more thing, (getting more mess up) I remove the battery from the plc trying to kinda reset the whole thing, however, the error LED keep flash now after i plug it back and turn on back the PLC. What's going on?

[Gambit 331]

Probably an error that the battery voltage is low. The only thing you can do is remove the battery and wait a while for the programming memory(RAM) to clear.

[Gunboy 0]

I switch the battery to another plc unit, it can work. Nvm, i will try go through the manual and find out what is that error LED means. Back to the main question, is it 'removing the battery and wait for the programming memory(RAM) to clear' the only way? If i get the SC09 cable, thats mean i will able to do programming communication no matter how the RS232 setting going wrong? So is it the D8120 really the reason that make the RS232 communication fall away? Thanks for your kind help.

[Gambit 331]

If you have a SC09 you can download again or change D8120. D8120 is the comm setting for the BD board. Depending on the settings you made you might still have access but via other connection settings

[Gunboy 0]

Here is the new situation of mine: The Error LED flash is normal that it might be due to RAM is cleared. Then i try to download back the original program into PLC again as it seen can be connected. However, the PLC become weird that i cant control it in the monitor mode. And i switch the power on off again, the Melsoft connected failed problem happen again!!? Why? So i have to unplug the battery again and repeat all the step, however till end the Melsoft connected failed problem still happen? Dont the D8120 or other setting is already cleared? Please help me on this.

[Gambit 331]

Make sure D8120 is 0 and no parameters are set for the BD board.

[Gunboy 0]

Ok, it works. I try execute the 'PLC memory clear' command on Melsoft and then power on off the PLC again, it seen can be connected still. Just wonder why the BD board parameter still be there even i pull out the battery, and it only gone when i execute the following command. Anyway, thanks for your advice.

[djtron 0]

Beside the battery is a capacitor, it can take up to some days I was told...