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MAX3232: Compatibility between ADM3251E and MAX3232

Part Number: MAX3232

Hello,

                I am using MAX3232 line driver on one board and ADM3251E on the other. So when I am trying to interface both the boards, the serial communication doesn't happen but when i tested both the boards independently, they are working fine. Any help is appreciated. 

Thanks and Regards,

Akhil Pillai

                    

  • Hi Akhil,

    Are there any other differences between the two boards besides choice of RS-232 transceiver? For example, are there any differences in connector pinout, application software/firmware, etc.? I ask because RS-232 is a standardized interface and transceivers from different vendors should interoperate as long as they meet the standard requirements.

    If there are no obvious differences in the boards' designs, then a good way to debug this would be to probe the signals at various points along the signal chain and observe them on an oscilloscope. That way, you could see if the data is successfully making it from the UART to the transceiver, if it is converted to proper RS-232 signals, if those signals make it across the cable to an RS-232 receiver, etc.

    Regards,
    Max
  • Akhil,

    Do you mean MAX3232 as the transmitter and ADM3251E as the receiver? Can you check the ground of the transmitter and receiver? RS-232 communication needs to have same grounding. Another place to check is the supply. Please make sure both ends are powered properly. Please let me know if you still have the issue.

    Regards,
    Hao
  • Hello Max,

                         Actually we have developed two different boards. The firmware and the components used in both of these boards are different. So one of these boards is actually supposed to send commands through a serial communication link. So when I transmit some data from MAX3232, at the reception side, the data is getting corrupted and I am not sure why! But the same thing works with a USB to RS232 Converter. 

    Thanks,

    Akhil

  • Hello Hao,


    I am using MAX3232 on one board for transmit/receive both and I am using ADM3251E on another board for the same. The ground is also same except for the one at ADM3251E, as it has isolated ground.

    Thanks,
    Akhil
  • Akhil,

    Like Max suggested, can you probe the signal along the communication chain with reference to a fixed ground? It might give us some clue. Can you also try to power both boards with one supply?

    Regards,
    Hao
  • Hello Hao,

    I viewed the signals in the oscilloscope and the voltage levels looks fine for me but then the data somehow gets corrupted! We tested shorting the isolated ground but that also doesn't seem to work. Both the boards are powered with the same power supply.

    Thanks and Regards,
    Akhil Pillai
  • Akhil,

    Have you checked if the input digital signal matches the output ones? You can do it by sending a pattern repeatedly. Can you also try different setup to see if any of them works, like MAX3232 to MAX3232, MAX3232 to ADM3251E, ADM3251E to MAX3232, ADM3251E to ADM3251E? If it doesn't look like hardware issue, you may want to check the software configuration, like baud rate, polarity bit, data bit, stop bit, etc.

    Regards,
    Hao
  • Hello Hao,

    Yes I have checked the input signals and i replaced the ICs, like having same line driver at both the ends, and it works fine! When i try to communicate between ADM and MAX, only at that point of time I am facing issues.
  • Akhil,

    Can you compare the RS-232 signal of 1) MAX3232 to MAX3232, 2) ADM3251E to ADM3251E, 3) MAX3232 to ADM3251E, 4) ADM3251E to MAX3232? If you see the same waveform in case 1) and 3), which means MAX3232's driver works fine. Similarly, comparing 2) and 4) you can check ADM3251E's driver, comparing 1) and 4) for MAX3232's receiver, comparing 2) and 3) for ADM3251E's receiver. Please let me know if it makes sense for debugging.

    Regards,

    Hao