Posted on December 15, 2004 at 13:34I built the powerline modems, using the ST7537, for my grad project, but I keep hitting a problem. Whenever I connect through a terminal program, the RTS pin goes to '0' (actually 12v). This, per the design, is also the Rx/Tx signal. The '0' sends it into transmit mode and then 1 second later, the autoswitching kicks it back into receive mode and there they stay. Thus I cannot communicate because the RTS never goes back to a '1' to reset the mode so it can transmit. The only way I've been able to communicate is to flip the TEST1 switch on one modem, which forces it to follow the Rx/Tx pin into transmit mode. Then I can transmit one way only. I've tried an external circuit to control the Rx/Tx line, but while I can communicate both directions then, it's all gibberish. I've also tried to find serial comm programs that leave the RTS pin at '1' until they are ready to transmit and then set it to '0', which is what the chip is expecting. Is there a program or a different circuit that I can use that will provide the proper signalling to the Rx/Tx pin? Thanks.
