KV Host Link Node-RED API Reference

This page is a user-facing index of the JavaScript KV Host Link client surface used by the Node-RED nodes. Use the usage guide for flow examples, and this page when you need to find the low-level operation name for a specific Host Link workflow.

The main low-level client type is HostLinkClient from lib/hostlink/client.js.

Connection And PLC Control

Operation	Public API
Open a ready-to-use connection	openAndConnect
Low-level client	HostLinkClient, constructor
Raw command exchange	sendRaw, sendRawDecoded
PLC mode and error control	changeMode, clearError, checkErrorNo, confirmOperatingMode
PLC model and clock	queryModel, setTime, MODEL_CODES
Connection lifecycle	connect, close

Device Operations

Operation	Public API
Single device read/write	read, write
Consecutive device read/write	readConsecutive, writeConsecutive
Forced bit/device control	forcedSet, forcedReset, forcedSetConsecutive, forcedResetConsecutive
Timer/counter set-value writes	writeSetValue, writeSetValueConsecutive
Monitor registration/cycle	registerMonitorBits, registerMonitorWords, readMonitorBits, readMonitorWords
Comment reads	readComments
Data bank switching	switchBank
Expansion unit buffer access	readExpansionUnitBuffer, writeExpansionUnitBuffer

High-Level Helpers

Operation	Public API
Address parsing and formatting	parseAddress, formatParsedAddress, normalizeAddress, normalizeAddressList
Device parsing and formatting	parseDevice, deviceToString, parseDeviceText, normalizeSuffix, resolveEffectiveFormat
Typed values	readTyped, writeTyped
Timer/counter composite reads	readTimerCounter, readTimer, readCounter
Named snapshots and polling	readNamed, writeNamed, poll
Word/dword reads	readWords, readDWords
Bit-in-word write	writeBitInWord

Protocol, Profile, And Diagnostics

Operation	Public API
Frame helpers	buildFrame, decodeResponse, decodeCommentResponse, ensureSuccess
Response token helpers	splitDataTokens, parseScalarToken, parseDataTokens
Profile lookup	PLC_PROFILES, normalizePlcProfile, displayName
Errors	ValueError, HostLinkBaseError, HostLinkError, HostLinkProtocolError, HostLinkConnectionError

Public Symbol Index

The low-level library module exports these public names:

CR, HostLinkBaseError, HostLinkClient, HostLinkConnectionError, HostLinkError, HostLinkProtocolError, MODEL_CODES, PLC_PROFILES, ValueError, buildFrame, decodeCommentResponse, decodeResponse, deviceToString, displayName, ensureSuccess, formatParsedAddress, normalizeAddress, normalizeAddressList, normalizePlcProfile, normalizeSuffix, openAndConnect, parseAddress, parseDataTokens, parseDevice, parseDeviceText, parseScalarToken, poll, readComments, readCounter, readDWords, readNamed, readTimer, readTimerCounter, readTyped, readWords, resolveEffectiveFormat, splitDataTokens, writeBitInWord, writeNamed, writeTyped.