485 problems caused by isolated power supply

485 parts of a recent project have been problematic and, eventually, due to the power supply system, the situation is as follows:

MCU TTL-232 signal after ADUM1211 bus isolation chip and interface board communication, 485IC power supply with recom 2405DC-DC, output of 5 and 485GND, of which 485 local modules using 485GND network copper, eventually found unable to communicate.

Cause Analysis:

1 just started to think of a possible TTL reference to the problem so jump ground, the results can send and receive, but after a few minutes the system will crash.

2 later will be recom DC-to remove, directly refer to the bus isolation chip back end of the power box, the wood and then appear in the crash.

Summarize:

In the communication should be noted that the signal line of reference power and signal to the correct, so that the signal line has a reliable reference level. Use isolated power supplies with caution.

485 problems caused by isolated power supply