Hi
I am using SN65HVD71DR 485 IC for RS485 communication.
In this only receiving section is working but transmission is not working.
Please suugest me some solution.
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Hi
I am using SN65HVD71DR 485 IC for RS485 communication.
In this only receiving section is working but transmission is not working.
Please suugest me some solution.
Hi
This is the circuit I am using for 485 communication.
And vldo is 3.3V.
I am giving data through the CON6.
And I am using pin 5 and pin 8
During transmission it gives same data back to Rx of the trasnmitter module and sends garbage data to receiver module.
Hi Michael,
Thanks for the additional info. There are several "DNP" components on the schematic. Are any populated? In particular it seems like R31 would be critical for transmitter functionality.
Are you able to observe D, Z, and Y on an oscilloscope to see if any issues can be seen in the waveforms?
Regards,
Max
Hi
The DNP components are not populated.
I am using D and Y so I think R31 wont be any effect.
I am also attaching the oscilloscope images of the data transfer ("at\r\n").
In the 1st image Red colour is the D pin signal and Yellow colour is the Y pin.
In the 2nd image Red colour is the D pin signal and Yellow colour is the Z pin.
Hi Michael,
It looks like there are several volts of "ringing" on the D input - do you know what could be causing this? I'm worried there may be some hardware issues related to that pin that prevent the signals from getting to the chip properly, since it looks like the output (Y/Z) is stuck high. Have you seen this behavior across a few chips, or is it possible this is something related to a single issue like a damaged component or poor solder connection?
Also, can you please confirm that HVD71 pin 3 connects to an MCU output and pin 2 connects to an MCU input? (From the net naming on your schematic I was worried these could be swapped.)
Regards,
Max