Hi I want to ask, I made a tool that is used to send digital scale data to the server. The digital scale that I use is the Nagata LCS-150L+RS232 digital scale and the tool I made uses Arduino Mega, RFID Wiegand, 4 channel relay module, MAX3232 RS232 to TTL module, ADUM1201 Digital Isolator, DC stepdown. As in the following picture:
Previously the tool I made was running smoothly, but suddenly an error occurred where when the tool I made was connected to a digital scale with an RS232 port, the direct weight reading value of the digital scale was unstable and was seen on the digital scale LED screen, going up and down by itself even though there was no load at all, but when the tool I made was not connected, the weight reading value would be stable. Can anyone help me solve this problem?
This may be a cause:
The ADUM1201 need to be supplied with two different isolated power supplies, otherwise there is no isolation between the input and output.
For the ADUM1201 I have provided a power supply that is different from the power supply for the Arduino Mega or the power supply for the pilot lamp. so I have 3 power supply.
For signal isolation you will need 2 seperate supplies for the ADUM1201
In your diagram the grounds of everything, including the scale, except the 24V supply and the pilot lamp are all connected together so nothing is isolated.
That is not what the diagram you show in post #1 indicates. It just shows ONE 5V connection to the ADUM.
It would be a good idea to show a complete schematic of how you actually have thing connected. Otherwise we have to make assumption as I did as to what could possibly be wrong and we will just go in circles.
sorry, I use 3 pilot lamps, but in the wiring picture I make it one.
And for the relay module the maximum is 10 A and for the maximum load current is 60 mA because each pilot lamp has a current of 20mA
Well if all 4 relays are active it would use 280mA and that is too much for the Mega, especially since you are powering many things from it's 5V output.
I would power the relays and RFID with a seperate 5V supply.
Does the 5V output of the Mega read 5V and is it stable?
You might have many things to correct in your circuit, but if the only problem presenting now is the original scale display value, you could start disconnecting components until it behaves ok.
If you disconnect Arduino from Adum, is it fine? And so on.
That gives you quick answer where the problem lays.
actually previously I did not use adum1201 and only used 2 separate power supplies for arduino mega and pilot lamp, and it worked normally. but after some time suddenly an error like this occurred, the digital scale reading value displayed on the digital scale led screen was unstable. Then I added ADUM1201 for isolation between arduino and max3232 + digital scale and separate additional power supplies for ADUM1201 and max3232 and it worked, but yesterday suddenly the error returned again the reading value became unstable again on the digital scale.
I tried one by one, and when I turned on the power supply for ADUM1201 and MAX3232, the reading of the scale weight value on the scale's LED screen became unstable. Then I tried without ADUM1201 so MAX3232 directly to Arduino Mega, and tried with another MAX3232 module, and the result was still error.
Yes, I have tried not to connect the max3232 and ADUM1201 to the Arduino Mega, and the result is still an error, the digital scale weight reading on the LED screen is still unstable.
