Viewer vs Generate

Mode defines the workspace's purpose. It is separate from a transport's connection state and from authorization to transmit instruments.

Start with an Empty Layout

1. Save wanted work. Choose Empty Layout at startup or clear the working Layout before entering Viewer, so saved values do not clutter incoming instruments.
2. Configure input in Setup and select Mode → Viewer (Rx). With no widgets entry is immediate. With existing widgets choose Clear, Keep Existing or Cancel. New/structurally modified Layouts offer Save & Clear instead; finish that save or cancel safely.
3. Clear removes working widgets. Keep Existing retains widgets/values, which compatible incoming streams can update. Cancel stays in Generate. All choices leave Sending stopped.
4. Use the transport's receive/reconnect controls. Watch connection status, NMEA Viewer and Diagnostics; do not authorize Sending to prove reception. Signal K publishing is not Viewer subscription.
5. As supported valid messages arrive, corresponding instruments appear automatically in their categories. Later matching samples update existing instruments.

Grouping and first-arrival order

RX uses the predefined Navigation, Propulsion, Environment, Tanks, Electrical, Communication and Other groups. It never automatically creates generator sources. Groups retain workspace category order, rather than becoming tabs sorted by reception time. Within a group each new stream uses the next free grid placement left to right, wrapping at configured width/span. In a fresh group this is first-arrival order, not numeric PGN order. Later updates do not reorder widgets. Retained/moved widgets and width/span changes affect placement. Dropdown numeric/alphabetic ordering is separate.

Source, device and instance

Matching uses message type, source and message-specific identity: engine instance; tank instance/type; temperature/humidity instance/source; wind reference; windlass identifier; AIS target; route/page keys. NMEA0183 uses talker identity (GP versus GN, for example) and formatter-specific identities. Matching configured instruments can all receive updates.

NMEA2000 NAME/source ownership is tracked within the transport session. Supported address changes can retain a known device; conflicting or reused addresses must not silently overwrite another live owner. Without NAME, address/session observations have less confidence. Inspect Object Tree and Diagnostics. Some discovery paths are bounded (expanded instruments, AIS streams and windlass streams); existing matches continue updating at capacity.

Reception, display and external Sending

A raw Diagnostics/NMEA Viewer entry does not establish a supported instrument decoder. Unsupported PGNs stay raw/opaque; malformed/unsupported sentences do not create a useful widget. Route attributes/geometry can update a passive cache without a widget. See Supported NMEA2000 PGNs and Supported NMEA0183 Sentences for direction/field limits.

Viewer suspends generators and ordinary Sending. Received/displayed values never authorize output. Saved RX Layouts are snapshots, not subscriptions to the original vessel.

Construct simulation data

1. Select Mode → Generate (Tx). Mode transitions revoke prior Sending.
2. Add an instrument from its category selector or load a reviewed Layout/Template.
3. Enter valid property values. A generator is optional; supported manual properties are enough for basic TX.
4. Configure individual Enable/reporting intervals and only then authorize external Sending when the intended transport is ready.

Understand transitions

Switching modes does not grant new Sending permission. Existing Enable states and saved values are configuration, not global authorization. A received Layout loaded later in Generate is a simulation snapshot: it does not reconnect to or subscribe to the original vessel. Confirm which local generator sources are enabled before letting them update captured values.

Bounded chartplotter/device service requests have their own explicit authorization and transport policy. Viewer restrictions on ordinary instruments must not be interpreted as permission to browse routes automatically. See Route Requests and Authorization.

Before and after isolated reception

Viewer before reception, with an empty Layout and Sending disabled. Click to enlarge.

Position, heading and depth instruments appear in first-arrival order as messages are received. Click to enlarge.

Illustrated controls

Figure 3. Viewer entry offers Clear, Keep Existing or Cancel. Sending is revoked before this choice. Click to enlarge.

Figure 4. Viewer shows received instruments while ordinary Sending is disabled. Click to enlarge.

Figure 5. Generate mode permits editing and simulation; switching modes does not authorize transmission. Click to enlarge.

Related topics

Introduction · System Requirements · Installation and First Launch · Quick Start · Loading the Default Layout · Connection Troubleshooting · Enable, Dispatch and Sending · Route Overview · Engineering Units

Help Home · Back to top