PJLink Input Switching: Map Connectors and Verify the Selected Source

PJLink input switching needs a model-specific connector map and a readback check. Do not assume that a connector labelled HDMI uses the same input number on another projector. Discover or document the available inputs, select the required one and verify the selected source independently from signal presence.

A command that selects a valid connector may still leave the screen blank. The connected player can be asleep, the video path can be negotiating or the projector can still be starting. Separate those outcomes in your commissioning checklist.

Create an input map with evidence

The Epson EB-PU series specification, section 3.4, provides both input-selection entries and an available-inputs query. Its table maps HDMI to 32 for the listed models and includes a model-dependent SDI entry. This is why a generic label-to-number assumption is unsafe.

Use readable logical source names in the project, with the device protocol parameter stored as configuration. A replacement projector should require editing the map, not rewriting every show cue that refers to the main player.

The example describes documentation fields; it is not a command for an unspecified projector.

Sequence power, selection and validation

Establish communication first. Epson's network configuration instructions cover addressing and PJLink credentials, both of which must be correct before input testing can be meaningful. Then confirm that the projector is in an operating state where input selection is available.

Send one selection and wait for its application response before checking the selected input. Avoid repeatedly sending a selection every time a screen refreshes. A stable input configuration should not create unnecessary commands or fight a technician using the local controls.

If the application response reports an invalid parameter, revisit the input map. If it reports that the action is unavailable now, inspect the power transition and device mode. A missing response is a communication ambiguity, not proof that the connector number was wrong.

Diagnose a blank screen after selection

Read back the selected input. If it matches the request, move investigation to the media path: player output, switching equipment, signal format and synchronization. If it does not match, inspect whether another controller, automatic input feature or local remote changed it again.

Run the test with a known static test image and a clearly labelled cable. Change only one element at a time. An input query cannot prove the correct video content, and a visible image cannot prove the controller has an accurate input state.

For sites that allow temporary manual selection, decide whether the system should preserve that choice or restore the scheduled source. Make restoration an explicit action with appropriate operator visibility, rather than an invisible background loop.

Acceptance after a model change

Verify each logical source from both standby startup and an already-running projector. Disconnect one source deliberately and confirm that the panel does not mislabel missing video as failed input selection. Restart the controller and ensure the current source is learned from feedback.

Archive the input map alongside model and firmware information. Recheck it whenever a projector, switcher or cable path changes.

Keep a labelled source test image identifying the player and output for handover. It helps staff distinguish selecting the right connector from receiving content from the wrong player. Record whether audio follows that source or uses another route. A successful picture switch can conceal an audio path still on the previous input. Test the combined operator experience, while keeping separate evidence for the input selection, video signal and audio routing decisions.

The Epson PJLink device reference provides a concrete model-specific example. For a multi-brand rollout, review your source maps with an integration partner before duplicating the configuration.