Node reference

On this page · 3 sections

26 node types, in three categories. A node's fields are set in the inspector; what is not set keeps the default shown here. This page is generated from studio-flows.js, so it is the engine as built.

Inputs

Timer timer

Sends a message every interval; the payload counts the ticks. 0 inputs, 1 output.

Field	Type	Default
every (every (ms))	number	1000
atStart (also at start)	boolean	true
topic	text	tick

Tag tag-in

A tag of a data source: every sample becomes a message with the tag as its topic. 0 inputs, 1 output.

Field	Type	Default	Meaning
tag	tag		source.tag
onChange (only when the value changes)	boolean	false

Panel control panel-event

An event of a component on the page: a setpoint request, a button, a selection. The payload is the event's value, or its whole detail. 0 inputs, 1 output.

Field	Type	Default	Meaning
component	component
event	event
field (detail field)	text	value	Which field of event.detail is the payload; empty takes the whole detail.

Inject inject

A fixed message, sent at start, whenever the node is triggered from the editor, and every so many milliseconds when repeat is set. 0 inputs, 1 output.

Field	Type	Default	Meaning
payload	text	1
topic	text
atStart (at start)	boolean	false
repeat (repeat every (ms))	number	0	0 sends only at start and on a trigger; 10 or more repeats at that interval.

HTTP request http-request

Requests a URL when a message arrives; the reply (JSON when it parses) is the payload. 1 input, 1 output.

Field	Type	Default
url	text	https://
method	select: GET, POST	GET
sendPayload (send the payload as JSON body)	boolean	false

JavaScript with the message as msg. Return the message to send it on, an array to send several, nothing to drop it. store keeps values between messages. This is code: a station runs it only when its configuration allows code, and then in a sandbox with a time limit; a page under a strict Content-Security-Policy refuses it. A Math node or a Formula node is not code. 1 input, 1 output.

Field	Type	Default	Meaning
code	code	msg.payload = msg.payload * 1;

Threshold threshold

Compares the payload with a value. When the condition becomes true and holds for the time given, a message leaves the first output; when it clears (below the clear value), one leaves the second. 1 input, 2 outputs (crossed, cleared).

Field	Type	Default	Meaning
op (condition)	select: >, >=, <, <=, ==, !=	>
value	number	0
clear (clears at)	number		Hysteresis: the value the condition clears at; empty uses the value itself.
for (holds for (ms))	number	0

Switch switch

Routes a message by a condition on one of its fields: the first output when it matches, the second otherwise. 1 input, 2 outputs (matches, otherwise).

Field	Type	Default	Meaning
field	text	payload	payload, topic, unit, quality or payload.field
op	select: ==, !=, >, >=, <, <=, contains, true, false	==
value	text

Math math

An expression on the payload, with x as the number: x * 9 / 5 + 32, with sqrt, min, max and the rest of Math, and msg for the message (msg.payload.active ? 3 : 2). A payload that is not a number is dropped unless the expression uses msg. The expression is read by the formula language, never run as code. 1 input, 1 output.

Field	Type	Default	Meaning
expression	text	x * 1
precision (decimals)	number		Rounds the result; empty keeps it.
unit (unit of the result)	text

Filter filter

Passes a message only when the payload changed by more than the deadband, and not more often than the interval. 1 input, 1 output.

Field	Type	Default	Meaning
deadband	number	0	The least change that passes; 0 passes every change.
interval (at most every (ms))	number	0
onlyNumbers (drop non-numbers)	boolean	true

Statistics statistics

Mean, minimum, maximum and RMS over the last N numbers, sent with every message. The payload is the chosen statistic, or the whole record. 1 input, 1 output.

Field	Type	Default	Meaning
window (samples)	number	20
output	select: mean, min, max, rms, record	mean

Delay delay

Sends the message on after a delay. 1 input, 1 output.

Field	Type	Default	Meaning
ms (delay (ms))	number	1000

Trigger trigger

On a message, sends one payload at once and another after a time; until then further messages are ignored. 1 input, 1 output.

Field	Type	Default
first (send first)	text	true
then (then send)	text	false
after (after (ms))	number	1000

Join join

Collects the payloads of different topics into one record { topic: payload } and sends the record whenever it changes, or on an interval. 1 input, 1 output.

Field	Type	Default	Meaning
interval (every (ms), 0 = on every change)	number	0
timestampField	text	timestamp

Change change

Sets the topic, the unit or a fixed payload on the message. 1 input, 1 output.

Field	Type	Meaning
topic	text	Empty keeps the topic.
unit	text
payload	text	Empty keeps the payload; JSON is parsed.

Template template

A text from the message: {{topic}}, {{payload}}, {{unit}}, {{payload.field}}. 1 input, 1 output.

Field	Type	Default	Meaning
template	code	{{topic}}: {{payload}} {{unit}}

Units convert

Converts the payload between units: temperature, pressure, flow, length, mass. The message's unit is set to the target. 1 input, 1 output.

Field	Type	Default
from	select: °C, °F, K, bar, psi, kPa, mbar, L/min, m³/h, gal/min, mm, in, m, ft, kg, lb	°C
to	select: °C, °F, K, bar, psi, kPa, mbar, L/min, m³/h, gal/min, mm, in, m, ft, kg, lb	°F
precision (decimals)	number	2

Smooth smooth

A low-pass filter: an exponential moving average of the payload. Alpha 1 passes the value as is, 0.1 follows it slowly. 1 input, 1 output.

Field	Type	Default	Meaning
alpha	number	0.2
precision (decimals)	number	3

Rate rate

The rate of change of the payload per second (or per minute), from one message to the next. 1 input, 1 output.

Field	Type	Default	Meaning
per	select: second, minute, hour	minute
precision (decimals)	number	3

Parse parse

Reads a text payload as a number (the first one in it, an instrument's "+1.2345E+00" included), as JSON, or as comma-separated fields into a record with the names given. 1 input, 1 output.

Field	Type	Default	Meaning
as	select: number, json, fields	number
names (field names)	text	a,b,c	For fields: the names of the comma-separated values, in order.
separator	text	,

Outputs

Panel indicator panel-set

Sets a property of a component on the page to the payload, or pushes the payload as a record (a chart's push). 1 input, 0 outputs.

Field	Type	Default	Meaning
component	component
property	property	value	A property name, or push for a chart.

Device write tag-out

Writes the payload to a tag of a data source: a setpoint to the PLC, a command to the instrument. The confirmed value comes back through the tag. 1 input, 0 outputs.

Field	Type	Default	Meaning
tag	tag

Alarm alarm

Raises an alarm on the first input and clears it on the second: on the page's alarm banner or grid, and on the agent's alarm list. The message going out carries the alarm record. 2 inputs (raise, clear), 1 output.

Field	Type	Default	Meaning
id	text		Empty uses the message topic.
tag	text
message	text	{{topic}} high ({{payload}} {{unit}})
priority	select: 1, 2, 3, 4	2
component (on component)	component		The alarm banner or grid whose alarms property is kept up to date; empty for none.

Log log

Appends the message to a log: a row of time, topic, payload and unit (a record's fields become columns). In the designer the rows download as CSV; on the agent the file is CSV or TDMS. 1 input, 0 outputs.

Field	Type	Default	Meaning
name (log name)	text	log
format	select: csv, tdms	csv	On the agent: a CSV file, or a TDMS file for any tool that reads TDMS (npTDMS among them).

Debug debug

Shows the message in the message inspector. 1 input, 0 outputs.

Field	Type	Default	Meaning
label	text

Notify notify

Posts the message as JSON to a webhook. 1 input, 0 outputs.

Field	Type	Default	Meaning
url	text