Noise in the SN75176 channel

CAMILO MELO

I have the next problem, I'm working with TI devices for make a rs485 interface (half duplex) ,

 I use a MAX3221IDBR  and SN75176BDR. one of the differential channel (channel B)

doesn't output the signal correctly, the output in channel A  is inverted but without noise than have

the channel B.   

For this reason,   I have tried to test only the rs232 interface with the PC and this

worked well, the RS232 signal in the output of the MAX was between -5V and 5V, later,

 I have put the SN75176 and the signal in the same point was between -0.8V and 7V.

 I really dont understand what happens. can someone help me?

over 13 years ago

0 Thomas Kugelstadt over 13 years ago

TI__Mastermind 28265 points

when you said you tried with the PC?

which PC connetor? certainly not your RS232 connector?

0 CAMILO MELO over 13 years ago in reply to Thomas Kugelstadt

Prodigy 20 points

Hi Thomas, thanks for answer, for me the PC is to connect the max3221 with a computer.
I made that with a RS232  to USB converter.

0 Thomas Kugelstadt over 13 years ago in reply to CAMILO MELO

TI__Mastermind 28265 points

Hi Camilo,

if you use a USB-to-RS232 converter then you cannot connect an RS485 application to it. For this you would need an additional RS232 to RS485 converter.

what is your end goal? what are you trying to accomplish?

regards, Thomas

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Noise in the SN75176 channel