Author Topic: safe to use RS232 "Y" splitter to connect one comport to two recipients?  (Read 5865 times)


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Hi all,
I'm hoping someone can help us out with a particular problem:

We have a piece of equipment that can send logging data through a parallel port to a printer, or ASCII data through a serial port to a computer, but not both at the same time.  The computer runs HyperTerminal for capturing the ASCII to a text file.  The printer is an old dot-matrix for printing the log.
We want to be able to log to the printer and computer at the same time, so that the computer would be a redundant backup in case the printer jams or fails .  The tested and working DB9 serial port connection to the computer is just three pins:
Pin2 - RXD
Pin3 - TXD
Pin5 - Ground
9600 baud, no parity, 8-bit, 1 stop-bit, no flow control
(Not sure if I even need the the RXD connected on the equipment-side, because it is only sending data, but haven't tested that yet.)

I was thinking to split the serial-out of the equipment with a simple "Y" adapter, so that one branch goes directly to the computer and the other branch goes to a serial-to-parallel converter for the printer.  Would this work, or will I fry something?  Maybe another option would be to split the parallel-out of the equipment so one branch goes directly to the printer and the other branch goes to a parallel-to-serial adapter.
Thanks for any help

Jan Axelson

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Re: safe to use RS232 "Y" splitter to connect one comport to two recipients?
« Reply #1 on: October 26, 2012, 02:18:22 pm »
RS-423 supports 1 driver and multiple receivers. So you could send the RS-232 output to an RS-232/423 converter and send the RS-423 output to two RS-232/RS423 converters. Send the resulting RS-232 outputs to the serial/parallel converter and the PC. This assumes no software handshaking (Xon/Xoff).

Or on the PC, write an application that sends the captured data to the printer port.

Or try a Y cable to send one driver output to two receiver inputs. If you don't tie multiple drivers together you likely won't break anything but it may or may not work.