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Communication Problem Regarding with MAX3221

Rineesh Sathyan
Prodigy 20 points
Other Parts Discussed in Thread: MAX3221

The hardware configuration is below .Normal mode operation (As per datasheet)

We are facing a problem related with MAX3221 RS 232 communication chip.

The chip is not properly work with communication port of PC. Here I have selected the communication port as default settings (baud rate=9600, data bit= 8, parity= none, stop bit= 1).Also tried with up to 57600 different bauds but no response.

The same hardware & PC settings are worked with (Prolific USB to COM port converter).

So I was doubt on COM port & checked the port by shorting of TX& RX Pin of port & tested with HyperTerminal (loopback).The PC’s port was working properly.

As per datasheet Data rate is


 

The min value of data rate is 150kbps. So whether it is working with baud rate 9600 to 57600?

  • Prodigy 130 points

    The min value of the "Maximum data rate" means that the device will work up to at least 150kpbs.

  • in reply to Martin Dorigatti
    Prodigy 10 points

    The desktops used to deliver TxD/ RxD signals ranging from +12V to -12V on the RS232 serial ports (9 pin D type connector).

    The USB to Serial converter deliver signals that are of lower levels +5 V on the D type connector.

    My observation is that the MAX3221 behaves differently depending on these signal levels.  In my case, it was working well when connected directly to the desktops, but failed to operate with the USB to Serial converter.