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Problem with rs232 module


I have a problem with rs232 module. I’m not able to write data from my PC to the rs232 module via serial port. I have a serial device which I normally connect to the rs232 module, and that works fine. I’m able to receive data just fine from this serial device, but I don’t receive any data sent from PC. This serial device connects to rs232 module directly with serial cable, but my PC doesn’t have a serial port, so I’m using a usb-to-serial converter cable. Do you think this cable can be the problem? I read something about hardware flow control support, but I don’t really understand what that means. Or do you have any ideas what I might be doing wrong?


Welcome to the Forum.
Perhaps this link can help:
May be that you do not have a “Null-Modem cable”


An equally valid problem that you may have is your USB-to-serial device is a TTL device not a RS232 device. You really need to find out what USB–>Serial device you have and what voltages it works at.


Handshaking will depend on the software on the PC and how it’s configured.

In situations like this, I tie pins 7 & 8 together (RTS and CTS) at the PC end. That way, if the PC software is using handshaking, this will ensure that communications will work.