QUOTE (jstolaruk @ Sep 15 2009, 05:59 AM)

If you haven't yet purchased the ML1200 get the ML1200R which gives you a 2nd port.
Otherwise, look into the 1747-DPS2 port splitter. I'm pretty sure that will do what you are looking for however I haven't had the opportunity to try one out.
There are several port "splitters" out there, aka "Port Multiplexers" for DF-1 protocol.
I've personally used the PLC09 from www.calta.com which gives you 3 serial ports from one. I've also used a Digi One IAP which gives you both a serial port and an Ethernet port. So in practice you plug the PLC into one serial port, the PV550 into the second serial port, and you can talk to EITHER device via the Ethernet port from your laptop or plug it into your LAN. Price-wise, I believe both will run you about the same cost so the big question will be whether you prefer serial or Ethernet access.