I2C Interoperability Issues

Projects Networking, Protocols, and Devices
1

Hello Everyone!

I have a really annoying problem which I can't solve alone and I am in dire need of Your help!

So, I have a setup where I have a Controllino Maxi (Arduino based PLC) connected to an UNO through I2C using the Wire.h library.
I added 2 pieces of 4.3komh pullup resistor to SDA and SCL. The communication between the 2 devices is perfect.

I also have an RFID Reader ID-12LA connected to the Rx pin. The communication between the sensor and the UNO/Controllino is perfect.

The problem comes when I connect all the 3 devices together and I try to send the read data from the sensor to the Controllino. So the connection so far looks like this:
RFID->(Serial TTL-ASCI)->UNO-> (Two Wire-I2C)->Controllino->Serial Monitor(PC).

When I read the RFID tag I get the result instead of 15D6A943D1 the result FFFF15D6FFA94FFF3D1FFF.

I have googled it but without success and I hope that You can help figuring out a solution for this problem. I can provide further information if needed so feel free to ask for them.

Thank you in advance.
Have a nice day!

2

TougHD:
Hello Everyone!

I have a really annoying problem which I can't solve alone and I am in dire need of Your help!

So, I have a setup where I have a Controllino Maxi (Arduino based PLC) connected to an UNO through I2C using the Wire.h library.
I added 2 pieces of 4.3komh pullup resistor to SDA and SCL. The communication between the 2 devices is perfect.

I also have an RFID Reader ID-12LA connected to the Rx pin. The communication between the sensor and the UNO/Controllino is perfect.

The problem comes when I connect all the 3 devices together and I try to send the read data from the sensor to the Controllino. So the connection so far looks like this:
RFID->(Serial TTL-ASCI)->UNO-> (Two Wire-I2C)->Controllino->Serial Monitor(PC).

When I read the RFID tag I get the result instead of 15D6A943D1 the result FFFF15D6FFA94FFF3D1FFF.

I have googled it but without success and I hope that You can help figuring out a solution for this problem. I can provide further information if needed so feel free to ask for them.

Thank you in advance.
Have a nice day!

I guess it is a wiring issue.
I also guess it is a coding issue.
I also guess it is a compatibility issue.

Guess which one is correct?

If you want a useful recommendation you will need to:

  • Post the smallest program that exhibits this issue.
  • Post a wiring diagram with part numbers and links to datasheets.

else all you will get is useless drivel like this.

Chuck.

3

And since the stuff works OK individually but not together, it could also be a power supply issue, so you might take that off the secret list as well.