Re: RS422 communication failure at elevated temperature
The Schematics are attached.
There are 3 more UART with same scheme are available in the processor board and all 4 UART sharing the 'ADDRESS LINES' and 'DATA LINES'.
In all four UARTs (Quad channel), only the channels B and C are failed (Channel A & D are always passed).
- - - Updated - - -
Further to analysis,
1) If I'm ignoring the status of LSR and reading the FIFO (Although it is not the proper method to read FIFO, for debugging I have done it), I got the expected data.
For example:
Tx data AA01 0E55. Rx is as follows,
LSR Status Read Data
~~~~~~~~~~ ~~~~~~~~~
61 (Data available) AA
61 (Data available) 01
61 (Data available) 0E
60 (Data not available) 55 (But physically data is available in the FIFO)
Then, there is malfunction happened between FIFO to RHR(Receive Holding Register), after sending the mentioned patterns (x2 / x6 / xA / xE).
2) The failure is occurred for the following condition,
1. If the processor board is in Higher temperature (> ~48 Deg C).
2. Only with one particular communication board, irrespective of this board temperature.