Communicating to Unix System or PLC to get tags


We are having a ABB 450 & ABB MP200 Controller communicating to Unix System in one of our projects.
Untill now we have done the communication with Siemens Wincc with windows DCOM settings and its working fine.
Similarly we want to communicate with Unix system and no idea what Settings have to be done on Unix System to communicate with Ignition installed another System(having windows 2003 server). So, please guide us

  1. If We want to communicate with existing Unix system with Windows 2003 Server(Ignition Installed), what settings have to be done to get tags(like DCOM).
  2. If we want to communicate directly with PLC Controllers, what OPC drivers have to be used to get tags.