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What this unit does

It polls Modbus devices on the RS-485 bus — PLCs, VSDs, scales, controllers — and serves everything it has read to the wozansi scada as an ordinary Modbus TCP device on port 502 over WiFi.

It is a polling concentrator, not a transparent gateway: it reads the bus on its own schedule and the SCADA reads a cached copy. So the SCADA can poll fast over WiFi while the RS-485 bus runs at 9600 baud, and a dead slave shows as a stale block instead of stalling the dashboard. Values are up to one poll interval old — right for supervision, wrong for a control loop.

Where things live

Page	Use it for
Home	Is it working? Bus, TCP and diagnostics at a glance, plus the log
Poll Map	Which registers to read, and testing them through the SCADA path
RS485	Everything about the wire: protocol, timing, device discovery, raw tests
TCP	What the SCADA connects to, and the register layout
Alarms	Watch a value, drive a relay, POST a webhook — for standalone use
System	Naming, time, password, the log, restart, factory reset

Wiring

Terminal	Goes to
A+	Device A (D+)
B−	Device B (D−)
GND	Signal ground — run it, do not rely on the earth
24V / GND	Panel 24 V DC supply

Daisy-chain the bus, do not star it. Fit 120 Ω termination at the two physical ends only. Every device on the segment needs the same baud and format, and a unique slave ID.

Getting it talking

WiFi — join KPJ-Gateway (password kpjgate1), open http://192.168.4.1, set your network, give it a static IP, restart.
RS485 — set protocol, baud and format to match the device, then restart. Haiwell is usually RTU 9600 8N1; a factory-default Delta DVP is ASCII 9600 7E1.
RS485 → Scan bus — before anything else. If nothing answers, use Auto-detect, which tries all 78 protocol/baud/format combinations.
Poll Map — add ONE block using the Address reference. Confirm it reads online on Home before adding more.
SCADA — add a Modbus TCP device pointing at this unit’s IP, port 502, then import the tag CSV from the TCP page. The WiFi page spells out the exact endpoint.
Standalone? Skip the SCADA. Install this page to your home screen from the browser menu, and set up Alarms to drive the relays.

When it will not talk

Symptom	Usually
Everything times out	A/B swapped, wrong baud or format, wrong protocol, or no common ground
One block times out	Wrong slave ID, or that device is off
Checksum errors	Termination, cable length, or a baud mismatch with another device
Exception 2 (illegal address)	Off-by-one — the manual is 1-based, this unit is 0-based
Exception 1 (illegal function)	Device does not support that function — try 3 instead of 4
Reads work, writes refused	The block is not marked writable, or it is function 2 or 4, which are read-only
SCADA connects but reads zeros	Reading the diagnostic range, or the block is offline
First character of every reply lost	DE release delay too long — drop it to 10µs on the RS485 page

The wire monitor on the RS485 page settles most of these in one look: bytes sent with nothing coming back is a wiring or direction problem; bytes coming back that still fail is a framing or address problem.

About

Product	wozansi gateway
Firmware	—
Hardware	ESP32 + ES32C14 24 V expansion board
Built by	KPJ Automation
Support	kpjmachines@gmail.com
Phone	—
Web	—

Part of the wozansi range alongside wozansi scada, wozansi count and wozansi master count. Made by KPJ Automation in South Africa.

Flashing

The RS-485 port sits on IO1/IO3 — the USB programming pins. Disconnect A and B before flashing over USB, or the upload traffic is driven onto a live bus. There is no serial monitor while the bus is running; the log on the Home page replaces it. OTA updates over WiFi stop the bus automatically, so OTA is the safer route once a unit is in a panel.