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BenJones

Mitsubish FX3u

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Hello all, I'm totally new to PLC's and PLC programming. I thought it wouldn't be hard to program in ladder logic but it seems realtively complicated when using Mitubishi GX IEC Developer as one has to move things from specific memory and data registers rather than just saying ' if X > Y then turn on Z'. So, we have chosen an FX3u and FX3u-4AD-ADP analogue input cards. I can turn on and off a digital outputs from digital inputs, but can not read from analog inputs and turn on a digital outputs from the analog input at present. I have connected the analog inputs to sensors and am using them to read 0-10 volts. I wish to turn on a digital output when the sensor gives 7 volts or more on the analog input. I wish to program in ladder and I have a library of function blocks but I'm not sure what to input into the blocks ('S' and 'd' for example). I have the manuals and I believe I have to use M8001 to set it to volts rather than mA. Then I need to use a MOV function block and a CMP (compare) function block to compare something is greater than something else, eg, if >7v turn on Y1. It all seems rather complicated and programming is not my forte. I'm sure that when I do it once it will all sink in but getting to that point ins the hard bit. Could anyone help with maybe an example bit of code.

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0-10V = 0=4000 (depending on the analog card used and setting) 7v = 2800 If your analog signal is in D0 then it would be GT block with on S1 D0 on S2 K2800 on D the ouyput you would like to set As for reading an analog signal from the analog card. Got to the mitsubishi website and download the FB It has an extensive help for wiring and programming the analog cards ScreenHunter_01_Jun._12_12.37.bmp Edited by Gambit

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The FX3U-4AD-ADP will store it's analog values into D8260-D8269 as indicated in the FX3U Analog Control Edition manual. From there, use a simple compare. I don't use IEC Developer, but in ladder, use the in-line compares, which look like this: [> D8260 K1200] Then turn on your output bit from the compare. [>= D8260 K1200]---(M0)

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Hello, Thank you both for your reply's and clear explanations, within seconds I had it up and working. Since last week I have made good progress Have a great day, Ben

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Hello Everyone, 

Need help with reading channel data of FX2N-4AD with FX3U Cpu. I have added all the logic and it works also. Problem is the FROM function stop reading/fetching data from FX2N-4AD after some time i.e couple of hours and value just hang. Like 502 or something, untill you reset the whole PLC. What could be the problem.

For the further info,

-I have connected the FX2N-4AD on the right of fX3U-64M.

-There are two extension blocks FX2N-16EX and FX2N-16EYR also added to the right of FX3U-64M

-Order of mounting....FX3U-64M > FX2N-16EX > FX2N-16EYR > FX2N-4AD > FX2N-4AD

 

I have tried using the 2nd special module connected at the end, but It showed similar problem after few hours of running. THis shows the Special blocks fx2n-4ad are okay. There is something wrong with PLC maybe? Please help

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