Block type: dashboardDisplay
Shows the current value of a bound signal as formatted text.
| Module |
nflow_blocks
|
| Library | Dashboard blocks |
| Type |
dashboardDisplay
|
| Label | Display |
Description
The Display block shows the instantaneous value of the bound signal as text, using the selected numeric format. It updates after every simulation step.
Ports
Input(s)
This block declares no input ports.
Output(s)
This block declares no output ports.
Parameters
| Parameter | Default value |
|---|---|
LabelPosition
|
Hide |
Binding
|
|
ShowInitialText
|
on |
Format
|
short |
Alignment
|
Center |
Opacity
|
1 |
Layout
|
Preserve dimensions |
FormatString
|
%d |
GridColor
|
[0.502, 0.502, 0.502] |
ShowGrid
|
on |
Inspector Keys
These serialized keys are exposed by the block inspector.
LabelPosition
Binding
ShowInitialText
Format
Alignment
Opacity
Layout
FormatString
GridColor
ShowGrid
Block Characteristics
| Block type | dashboardDisplay |
| Family | Dashboard blocks |
| Rendered size | 180 x 40 |
| Phases | INIT, AFTER_STEP |
| Direct feedthrough | see Algorithms |
| Internal state or history | yes |
| Signal data type | double numeric values |
Algorithms
Extended Capabilities
This page describes the native runtime behavior observed in the module C++ sources. Declared phases indicate when the simulation engine calls the block.
Code generation: supported for C and Rust.
Implementation Sources
modules/nflow_blocks/libraries/dashboard/library.json{
"id": "builtin.dashboard",
"title": "Dashboard",
"version": "1.0.0",
"format": "nflow-2",
"metadata": {
"author": "Allan CORNET",
"created": "2026-08-07",
"tool": "Nelson nflow"
},
"comment": "Interactive controls and signal displays",
"license": "LGPL-3.0",
"builtin": true,
"blocks": [
{
"type": "dashboardScope",
"label": "Dashboard Scope",
"icon": "dashboardScope.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 230,
"height": 165,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"TimeSpan": "auto",
"LegendPosition": "Top",
"ScaleAtStop": "on",
"UpdateMode": "Wrap",
"NormalizeYAxis": "off",
"TicksPosition": "Outside",
"TickLabels": "All",
"Grid": "All",
"Border": "on",
"Markers": "off",
"FontColor": [
0,
0,
0
],
"YLimits": [
-3,
3
],
"Colors": []
},
"render": {
"type": "math",
"formula": "Dashboard Scope"
}
},
{
"type": "dashboardDisplay",
"label": "Display",
"icon": "dashboardDisplay.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 180,
"height": 40,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"Format": "short",
"Alignment": "Center",
"Opacity": "1",
"Layout": "Preserve dimensions",
"FormatString": "%d",
"GridColor": [
0.502,
0.502,
0.502
],
"ShowGrid": "on"
},
"render": {
"type": "math",
"formula": "Display"
}
},
{
"type": "dashboardEdit",
"label": "Edit",
"icon": "dashboardEdit.svg",
"phases": [],
"width": 150,
"height": 30,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"Alignment": "Center",
"Opacity": "1"
},
"render": {
"type": "math",
"formula": "Edit"
}
},
{
"type": "dashboardGauge",
"label": "Gauge",
"icon": "dashboardGauge.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 125,
"height": 140,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleColors": [],
"Limits": [
0,
-1,
100
],
"FontColor": [
0,
0,
0
],
"Opacity": "1",
"ScaleDirection": "Clockwise"
},
"render": {
"type": "math",
"formula": "Gauge"
}
},
{
"type": "dashboardHalfGauge",
"label": "Half Gauge",
"icon": "dashboardHalfGauge.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 156,
"height": 108,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleColors": [],
"Limits": [
0,
-1,
100
],
"FontColor": [
0,
0,
0
],
"Opacity": "1",
"ScaleDirection": "Clockwise"
},
"render": {
"type": "math",
"formula": "Half Gauge"
}
},
{
"type": "dashboardKnob",
"label": "Knob",
"icon": "dashboardKnob.svg",
"phases": [],
"width": 110,
"height": 115,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleType": "Linear",
"Limits": [
0,
-1,
100
]
},
"render": {
"type": "math",
"formula": "Knob"
}
},
{
"type": "dashboardLamp",
"label": "Lamp",
"icon": "dashboardLamp.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 65,
"height": 60,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"ColorDefault": [
0.7529411764705882,
0.7529411764705882,
0.7529411764705882
],
"StateColors": [
{
"Value": 0,
"Color": [
0.392156862745098,
0.8313725490196079,
0.07450980392156863
]
}
],
"Opacity": "1"
},
"render": {
"type": "math",
"formula": "Lamp"
}
},
{
"type": "dashboardLinearGauge",
"label": "Linear Gauge",
"icon": "dashboardLinearGauge.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 210,
"height": 90,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleColors": [],
"Limits": [
0,
-1,
100
],
"FontColor": [
0,
0,
0
],
"Opacity": "1",
"ScaleDirection": "Clockwise"
},
"render": {
"type": "math",
"formula": "Linear Gauge"
}
},
{
"type": "dashboardMultiStateImage",
"label": "MultiStateImage",
"icon": "dashboardMultiStateImage.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 190,
"height": 180,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"State": 0,
"Size": [
0,
0
],
"Image": "",
"Thumbnail": ""
}
],
"DefaultImage": {
"Size": [
0,
0
],
"Image": "",
"Thumbnail": ""
},
"ScaleMode": "Fill with fixed aspect ratio"
},
"render": {
"type": "math",
"formula": "MultiStateImage"
}
},
{
"type": "dashboardPushButton",
"label": "Push Button",
"icon": "dashboardPushButton.svg",
"phases": [],
"width": 91,
"height": 44,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"ButtonText": "Button",
"OnValue": "1",
"Opacity": "1",
"ButtonType": "Momentary",
"Icon": "None",
"CustomIcon": "",
"IconAlignment": "Left",
"IconOnColor": [
0,
0.392156862745098,
0
],
"IconOffColor": [
0,
1,
0
],
"IconColor": "Off"
},
"render": {
"type": "math",
"formula": "Push Button"
}
},
{
"type": "dashboardQuarterGauge",
"label": "Quarter Gauge",
"icon": "dashboardQuarterGauge.svg",
"phases": [
"INIT",
"AFTER_STEP"
],
"width": 140,
"height": 160,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleColors": [],
"Limits": [
0,
-1,
100
],
"FontColor": [
0,
0,
0
],
"Opacity": "1",
"ScaleDirection": "Clockwise"
},
"render": {
"type": "math",
"formula": "Quarter Gauge"
}
},
{
"type": "dashboardRadioButton",
"label": "Radio Button",
"icon": "dashboardRadioButton.svg",
"phases": [],
"width": 135,
"height": 115,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ButtonGroupName": "Group",
"States": [
{
"Value": 0,
"Label": "Label1"
},
{
"Value": 1,
"Label": "Label2"
},
{
"Value": 2,
"Label": "Label3"
}
],
"UseEnumeratedDataType": "off",
"EnumeratedDataType": "",
"Opacity": "1"
},
"render": {
"type": "math",
"formula": "Radio Button"
}
},
{
"type": "dashboardRockerSwitch",
"label": "Rocker Switch",
"icon": "dashboardRockerSwitch.svg",
"phases": [],
"width": 55,
"height": 100,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"Value": 0,
"Label": "Off"
},
{
"Value": 1,
"Label": "On"
}
]
},
"render": {
"type": "math",
"formula": "Rocker Switch"
}
},
{
"type": "dashboardRotarySwitch",
"label": "Rotary Switch",
"icon": "dashboardRotarySwitch.svg",
"phases": [],
"width": 125,
"height": 100,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"Value": 0,
"Label": "Off"
},
{
"Value": 1,
"Label": "Low"
},
{
"Value": 2,
"Label": "Medium"
},
{
"Value": 3,
"Label": "High"
}
],
"UseEnumeratedDataType": "off",
"EnumeratedDataType": ""
},
"render": {
"type": "math",
"formula": "Rotary Switch"
}
},
{
"type": "dashboardSlider",
"label": "Slider",
"icon": "dashboardSlider.svg",
"phases": [],
"width": 200,
"height": 90,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"ScaleType": "Linear",
"Limits": [
0,
-1,
100
]
},
"render": {
"type": "math",
"formula": "Slider"
}
},
{
"type": "dashboardSliderSwitch",
"label": "Slider Switch",
"icon": "dashboardSliderSwitch.svg",
"phases": [],
"width": 120,
"height": 45,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"Value": 0,
"Label": "Off"
},
{
"Value": 1,
"Label": "On"
}
]
},
"render": {
"type": "math",
"formula": "Slider Switch"
}
},
{
"type": "dashboardToggleSwitch",
"label": "Toggle Switch",
"icon": "dashboardToggleSwitch.svg",
"phases": [],
"width": 55,
"height": 100,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"Value": 0,
"Label": "Off"
},
{
"Value": 1,
"Label": "On"
}
]
},
"render": {
"type": "math",
"formula": "Toggle Switch"
}
},
{
"type": "dashboardCallbackButton",
"label": "Callback Button",
"icon": "dashboardCallbackButton.svg",
"phases": [],
"width": 110,
"height": 35,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Top",
"Binding": null,
"ShowInitialText": "off",
"ButtonText": "Callback Button",
"ButtonType": "Momentary",
"ClickFcn": "",
"OnValue": 1,
"PressDelay": "500",
"PressFcn": "",
"RepeatInterval": "0",
"AutoActivate": true,
"fixedAspectRatio": "off"
},
"render": {
"type": "math",
"formula": "Callback Button"
}
},
{
"type": "dashboardCheckBox",
"label": "Check Box",
"icon": "dashboardCheckBox.svg",
"phases": [],
"width": 135,
"height": 30,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"Label": "Label",
"Values": [
0,
1
],
"Opacity": "1"
},
"render": {
"type": "math",
"formula": "Check Box"
}
},
{
"type": "dashboardComboBox",
"label": "Combo Box",
"icon": "dashboardComboBox.svg",
"phases": [],
"width": 160,
"height": 25,
"inputs": [],
"outputs": [],
"defaultParams": {
"LabelPosition": "Hide",
"Binding": null,
"ShowInitialText": "on",
"States": [
{
"Value": 0,
"Label": "Label1"
},
{
"Value": 1,
"Label": "Label2"
},
{
"Value": 2,
"Label": "Label3"
}
],
"UseEnumeratedDataType": "off",
"EnumeratedDataType": "",
"Opacity": "1"
},
"render": {
"type": "math",
"formula": "Combo Box"
}
}
]
}
modules/nflow_blocks/src/cpp/DashboardHandlers.cpp//=============================================================================
// Copyright (c) 2026-present Allan CORNET (Nelson)
//=============================================================================
// This file is part of Nelson.
//=============================================================================
// LICENCE_BLOCK_BEGIN
// SPDX-License-Identifier: LGPL-3.0-or-later
// LICENCE_BLOCK_END
//=============================================================================
#include "BlockRegistry.hpp"
#include "SimEngineTypes.hpp"
#include <algorithm>
//=============================================================================
namespace Nelson::NFlow {
//=============================================================================
static bool
dashboardPath(const nlohmann::json& binding, std::vector<std::string>& path)
{
path.clear();
if (!binding.is_object() || !binding.contains("blockPath")) {
return false;
}
const auto& value = binding["blockPath"];
if (value.is_string()) {
const std::string id = value.get<std::string>();
if (!id.empty()) {
path.push_back(id);
}
} else if (value.is_array()) {
for (const auto& item : value) {
if (item.is_string() && !item.get<std::string>().empty()) {
path.push_back(item.get<std::string>());
}
}
}
return !path.empty();
}
//=============================================================================
static bool
readSubsystemOutput(const BlockState::SubsystemState& subsystem,
const std::vector<std::string>& path, size_t pathIndex, int port, std::vector<double>& values,
std::vector<double>& valuesImag, std::vector<long long>& valuesI64, int& exactType)
{
if (pathIndex >= path.size()) {
return false;
}
auto found = subsystem.nameToId.find(path[pathIndex]);
if (found == subsystem.nameToId.end()) {
return false;
}
const BlockId nid = found->second;
if (nid < 0 || nid >= static_cast<BlockId>(subsystem.blocks.size())
|| nid >= static_cast<BlockId>(subsystem.blockStateVec.size())) {
return false;
}
if (pathIndex + 1 < path.size()) {
const auto& nested = subsystem.blockStateVec[nid].subsystem;
return nested
&& readSubsystemOutput(
*nested, path, pathIndex + 1, port, values, valuesImag, valuesI64, exactType);
}
const Block& source = subsystem.blocks[nid];
if (port < 0 || port >= source.outputs) {
return false;
}
int offset = -1;
int width = 1;
exactType = static_cast<int>(SigType::Double);
if (!subsystem.portBase.empty() && nid < static_cast<BlockId>(subsystem.portBase.size())) {
const int gpi = subsystem.portBase[nid] + port;
if (gpi >= 0 && gpi < static_cast<int>(subsystem.sigs.size())) {
const PortSig& sig = subsystem.sigs[gpi];
offset = sig.offset;
width = std::max(1, sig.width());
exactType = static_cast<int>(sig.type);
if (sig.isComplex && offset >= 0
&& offset + width <= static_cast<int>(subsystem.outputsImagVec.size())) {
valuesImag.assign(subsystem.outputsImagVec.begin() + offset,
subsystem.outputsImagVec.begin() + offset + width);
}
if (portUsesI64(sig) && offset >= 0
&& offset + width <= static_cast<int>(subsystem.outputsI64Vec.size())) {
valuesI64.assign(subsystem.outputsI64Vec.begin() + offset,
subsystem.outputsI64Vec.begin() + offset + width);
}
}
}
if (offset < 0 && nid < static_cast<BlockId>(subsystem.outputBase.size())) {
offset = subsystem.outputBase[nid] + port;
}
if (offset < 0 || offset + width > static_cast<int>(subsystem.outputsVec.size())) {
return false;
}
values.assign(
subsystem.outputsVec.begin() + offset, subsystem.outputsVec.begin() + offset + width);
return true;
}
//=============================================================================
static bool
readDashboardSignal(SimCtx& ctx, const nlohmann::json& binding, std::vector<double>& values,
std::vector<double>& valuesImag, std::vector<long long>& valuesI64, int& exactType)
{
if (!binding.is_object() || binding.value("kind", std::string()) != "signal") {
return false;
}
std::vector<std::string> path;
if (!dashboardPath(binding, path)) {
return false;
}
auto found = ctx.nameToId.find(path.front());
if (found == ctx.nameToId.end()) {
return false;
}
const BlockId nid = found->second;
const int port = std::max(1, binding.value("outputPortIndex", 1)) - 1;
if (nid < 0 || nid >= static_cast<BlockId>(ctx.blocks.size())
|| port >= ctx.blocks[nid].outputs) {
return false;
}
if (path.size() > 1) {
const auto& subsystem = ctx.blockState[nid].subsystem;
return subsystem
&& readSubsystemOutput(
*subsystem, path, 1, port, values, valuesImag, valuesI64, exactType);
}
const int offset = slotOf(ctx, nid, port);
const int width = outputWidth(ctx, nid, port);
if (offset < 0 || width <= 0 || offset + width > static_cast<int>(ctx.outputs.size())) {
return false;
}
values.assign(ctx.outputs.begin() + offset, ctx.outputs.begin() + offset + width);
const PortSig* signal = portSigOf(ctx, nid, port);
exactType = static_cast<int>(signal ? signal->type : SigType::Double);
if (signal && signal->isComplex && ctx.outputsImag
&& offset + width <= static_cast<int>(ctx.outputsImag->size())) {
valuesImag.assign(
ctx.outputsImag->begin() + offset, ctx.outputsImag->begin() + offset + width);
}
if (signal && portUsesI64(*signal) && ctx.outputsI64
&& offset + width <= static_cast<int>(ctx.outputsI64->size())) {
valuesI64.assign(
ctx.outputsI64->begin() + offset, ctx.outputsI64->begin() + offset + width);
}
return true;
}
//=============================================================================
static bool
handleDashboardObserver(SimCtx& ctx, const Block& block, Phase phase)
{
BlockState& state = getState(ctx, block.nid);
if (phase == Phase::INIT) {
state.scalar = 0.0;
state.scalar2 = 0.0;
state.displayValues.clear();
state.displayValuesImag.clear();
state.displayValuesI64.clear();
state.scopeSeries.clear();
state.scopeSeriesImag.clear();
state.scopeSeriesI64.clear();
state.xSeries.clear();
state.scopeExactType = static_cast<int>(SigType::Double);
state.dashboardTouched = false;
state.dashboardError.clear();
return false;
}
if (phase != Phase::AFTER_STEP) {
return false;
}
const nlohmann::json binding = block.params.value("Binding", nlohmann::json());
std::vector<double> values;
std::vector<double> valuesImag;
std::vector<long long> valuesI64;
int exactType = static_cast<int>(SigType::Double);
if (!readDashboardSignal(ctx, binding, values, valuesImag, valuesI64, exactType)) {
state.scalar2 = 0.0;
return false;
}
state.scalar2 = 1.0;
state.scopeExactType = exactType;
state.scalar = values.empty() ? 0.0 : values.front();
state.displayValues = values;
state.displayValuesImag = valuesImag;
state.displayValuesI64 = valuesI64;
state.dashboardTouched = true;
if (block.type == "dashboardScope") {
if (state.scopeSeries.size() != values.size()) {
state.scopeSeries.assign(values.size(), std::vector<double> {});
}
if (!valuesImag.empty() && state.scopeSeriesImag.size() != valuesImag.size()) {
state.scopeSeriesImag.assign(valuesImag.size(), std::vector<double> {});
}
if (!valuesI64.empty() && state.scopeSeriesI64.size() != valuesI64.size()) {
state.scopeSeriesI64.assign(valuesI64.size(), std::vector<long long> {});
}
for (size_t i = 0; i < values.size(); ++i) {
state.scopeSeries[i].push_back(values[i]);
}
for (size_t i = 0; i < valuesImag.size(); ++i) {
state.scopeSeriesImag[i].push_back(valuesImag[i]);
}
for (size_t i = 0; i < valuesI64.size(); ++i) {
state.scopeSeriesI64[i].push_back(valuesI64[i]);
}
state.xSeries.push_back(ctx.t);
}
return false;
}
//=============================================================================
static bool
handleDashboardControl(SimCtx&, const Block&, Phase)
{
return false;
}
//=============================================================================
void
registerDashboardHandlers(BlockRegistry& registry)
{
const char* observers[] = { "dashboardScope", "dashboardDisplay", "dashboardGauge",
"dashboardHalfGauge", "dashboardQuarterGauge", "dashboardLinearGauge", "dashboardLamp",
"dashboardMultiStateImage" };
for (const char* type : observers) {
registry.registerHandler(
type, handleDashboardObserver, { Phase::INIT, Phase::AFTER_STEP }, "builtin.dashboard");
}
const char* controls[] = { "dashboardEdit", "dashboardKnob", "dashboardSlider",
"dashboardPushButton", "dashboardRotarySwitch", "dashboardRadioButton", "dashboardComboBox",
"dashboardCheckBox", "dashboardRockerSwitch", "dashboardSliderSwitch",
"dashboardToggleSwitch", "dashboardCallbackButton" };
BlockMetadata metadata;
metadata.interactive = true;
for (const char* type : controls) {
registry.registerHandler(type, handleDashboardControl, {}, "builtin.dashboard", metadata);
}
}
//=============================================================================
} // namespace Nelson::NFlow
//=============================================================================
| Version | Description |
|---|---|
| 1.0.0 | initial version |