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Talking to a rs 232 device with a 485 converter..

Jesse E
Prodigy 20 points

Hello all,

New to this forum and I am a completely dummy when it comes to communication. I am limited on the cables I have and am wondering if this would work. I am attempting to talk to a flow transmitter that has 232 communication. the device has 3 pins to connect to. I currently have a usb serial cable ("black box" cable with 9 male pins). I also have a kayden sca cable which I believe is a rs 232 to 485 converter. can I plug this into the serial cable, and then run 3 wires from the terminal connections (transit, receive, gnd)  to the 3 pins (clamp them onto pins) on the flow transmitter to connect? or will this not work since this is a 232 to 485 converter and the device uses 232. attached are some pictures

    

  • 0
    TI__Guru 62910 points
    Hi Jesse,

    For some reason the pictures don't seem to be coming through - can you please re-upload them? Otherwise I'm having a little trouble understanding the intended connections. In general, though, RS-232 and RS-485 are not interoperable with one another. However, if you are able to use the 232/485 converter to ensure you are making a 232-to-232 connection you may be able to get things working. Are you sure that you know the correct pin mappings for all the connections as well? (That will be important, so you don't connect two transmitters or two receivers together, unintentionally ground a port, etc.)

    Regards,
    Max
  • 0 in reply to Max Robertson
    Prodigy 20 points

    Max,

    Hopefully these pictures attached properly this time

  • 0 in reply to Jesse E
    TI__Guru 62910 points
    Jesse,

    It's tough to say for sure. If the USB cable is marketed as a USB-to-serial converter, then I would guess that it is converting to RS-232. It would most likely use a standard pinout on the connector, so you could look at up and figure out which lines are transmit, receive, and ground. If you knew which of the three pins on your device were which, then, you might be able to get a working connection. I say "might" because I'm not sure how the adapter was designed. There are other signals that are used in RS-232 to indicate status (ready to send/receive/etc.) and control the flow of data. If these aren't needed for operation you can get away with using just the TX and RX lines, but the adapter may expect all the RS-232 lines to be handled somehow. I'd probably give it a try and see if it works, and if you have an oscilloscope handy you can take a look to see if you can observe what look like standard RS-232 signals.

    Regards,
    Max