connect two serial port instances from a (ruby) program to a physical serial port (usb0)

Question

I have a program (jruby with rxtx on ubuntu-machine) which opens 2 seperate serial ports. Is it possible to connect both of them to one hardware port i.e. ttyUSB0, or alternatively to a virtual serial port (I have a program to simulate the hardware)?

Is there something like a software repeater/hub to connect 2 serial ports? I checked socat but this one only connects 2 ends with one another. I have read hint for vde2 and hint for slip/slattach but could not find a solution.

No socat specialists out there?

I would recomend to check if there is any Java libs available. Because you using JRuby, calling Java from your code is very easy. — arkadiy kraportov
Thanks for the hint. I did not want to change my jruby code, I rather like to solve this external, like prepare ports for use... — user2025166

user2025166 user2025166 · Accepted Answer · 2013-04-08T08:44:33

I finaly could solve this problem only with port ownership in the java class. No way with socat, I think because of the framing problems.

I created an ownership handler like in

Managing Serial Port Ownership (in rxtx)

in jruby it looks like

class SerialOwnershipHandler
include CommPortOwnershipListener

def initialize serial_port
  @serial_port = serial_port
  @id = serial_port.id
  @port_name = serial_port.port_name
end

def ownershipChange type
  case type
    when CommPortOwnershipListener::PORT_OWNED
      p @id.to_s + "  OwnershipListener: got the port for " + @port_name.to_s
      #break
    when CommPortOwnershipListener::PORT_UNOWNED
      p @id.to_s + "  OwnershipListener: just lost it's port ownership for " + @port_name.to_s
      #break
    when CommPortOwnershipListener::PORT_OWNERSHIP_REQUESTED
      p @id.to_s + "  OwnershipListener: someone is asking port ownership for " + @port_name.to_s
      @serial_port.close
      #break
  end
end...

In my serial port class initialize method I call

    @serial_ownership_handler = SerialOwnershipHandler.new self  ## implements CommPortOwnershipListener
    @port_id.add_port_ownership_listener @serial_ownership_handler

Only disadvantage. You cannot have more than one open line. You have to always close one connection before opening anohter one (the one who requests the port)

connect two serial port instances from a (ruby) program to a physical serial port (usb0)

1 Answers