The normal mode of using Phindows (without the -n option) causes a private session of Photon to be started on the QNX machine you've connected to.
The normal mode of using Phindows (without the -n option) causes a private session of Photon to be started on the QNX machine you've connected to. Your Photon session is independent of everyone else's.
The -n command-line option lets a Phindows client see and interact with any Photon session already running on one of the QNX machines in the same QNX network you've connected to. An exact copy of the remote Photon user's screen is displayed on your Windows desktop. In addition, you can use your mouse and keyboard to interact directly with that remote Photon session. You can, in effect, take over the remote screen as if you were sitting there.
Remote support example
For example, if you want to provide support to a remote QNX site that's running Photon, dial up and log into that QNX machine using Phindows with a command line similar to:phindows.exe -mcom2 -n/dev/photon
At this point, phrelay is informed that a connection to an already-existing Photon session called /dev/photon is requested (i.e. the Photon running on the local console). The phrelay command creates a graphics region to overlay the entire console graphics region, so that both your mouse and the remote mouse can control the same cursor. You can then share that remote desktop with the remote user.
Of course, there's no need to have a human actually sitting at the remote console. Nor is there a need even to have a physical screen and keyboard at the remote site. You can use Photon connectivity to control remote sites that are completely unstaffed. This not only saves on travel costs involved in remote diagnostics and maintenance, but also saves in hardware costs at the remote site (since you can eliminate the cost of keyboards and display screens).