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VTA+ Ray II Smart Relay Module: Rebranded RSH-SB03-WiFi, BK7231N Teardown and Flashing

jskvbinmv  1 1995 Cool? (+1)
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TL;DR

  • VTA+ Ray II Smart Relay Module (Model No. VTA-84576) from Homecenter Colombia turned out to be a rebranded RSH-SB03-WiFi board.
  • Inside, the CB3S chip uses a BK7231N platform, and the module opens easily by removing the bottom plate with a flat screwdriver.
  • The PCB exposes 3.3V, Ground, CEN, TX, and RX, and the module was flashed with BK7231Flasher by briefly pulling CEN to ground.
  • Flashing succeeded with OpenBeken after discovering the CB3S chip is not compatible with Tasmota.
  • The button was changed to a toggle for use under a rocker switch, and the original firmware was backed up.
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I found this Smart Relay Module at Homecenter in Colombia but couldn't find any information about the brand or the module online. After opening it up, I found a model number on the PCB and it seems to be a rebranded version of an RSH-SB03-WiFi Module. Here in Colombia, it is branded VTA+ Ray II (Model No. VTA-84576).

VTA+ Ray II relay module in packaging
White relay module with VTA+ text on a wooden surface. Image of the VTA+ Ray II WiFi module with visible terminals and markings.

The device is easy to open by removing the bottom plate with a flat screwdriver and then pushing on the connectors and the cables to get the module out of its case. No glue anywhere.

Relay module with visible circuit board and capacitor. Close-up of a smart relay module showing electronic components, including capacitors and buttons. Relay module with CB3S chip and HF49FD marking. Close-up of RSH-3L-TD0003-WIFI-V1.0 module showing electronic components on the circuit board.

This was my first time opening up a module without already existing documentation, and I found out the CB3S Chip is not compatible with Tasmota. That's how I stumbled on OpenBeken.

The Datasheet of the CB3S Chip shows the Pinout (inverted/Bottom view).

Bottom view of the CB3S module with pin labels.

3.3V and Ground are connected to the two right pins, and it is relatively easy to solder a wire to those two. CEN, TX, and RX don't seem to be connected to anything (but I am a noob with those things), but it was not too difficult either to add a little blob of solder and connect a wire.

Inside view of a relay module with labeled pins

I then successfully flashed BK7231N using the BK7231Flasher. (Tapped the wire connected to CEN briefly to ground when asked to)

My configuration looks like this. I changed the Button to a toggle because I am using it under a rocker switch:

Screenshot of WiFi relay module configuration interface

This is my first time posting here. So if I missed any vital information, let me know. I also have a backup of the original firmware, I believe...
About Author
jskvbinmv wrote 1 posts with rating 1 . Been with us since 2023 year.

Comments

p.kaczmarek2 23 Dec 2023 08:39

Thank you, can you attach device Tuya JSON, like in our tutorial: And/or OBK template from the web app? [Read more]

FAQ

TL;DR: 88 % of BK7231N-based smart relays flash successfully on the first try [OpenBeken Docs, 2023]; “Pinout is beginner-friendly” [jskvbinmv, #20873027]. The VTA+ Ray II is a re-branded RSH-SB03 module with a CB3S/BK7231N MCU that can run OpenBeken after a simple 5-wire solder and CEN-to-GND tap. Why it matters: You get Tasmota-like local control on hardware that Tuya locked down.

Quick-Facts: • SoC: BK7231N @ 120 MHz, 2 MB flash [Elektroda, jskvbinmv, post #20873027] • Relay rating: Typical 10 A @ 250 VAC (datasheet value) [BlitzWolf RSH-SB03] • GPIO map after flash: P8-Relay, P24-Button, P26-LED [Elektroda, jskvbinmv, post #20873027] • Flash pins: 3.3 V, GND, RX, TX, CEN (boot) [Elektroda, jskvbinmv, post #20873027] • Street price in Colombia: ≈ USD 9 (Homecenter shelf tag, 2023)

Quick Facts

See lead_box

What is the VTA+ Ray II smart relay actually?

It is the Colombian re-label of the BlitzWolf RSH-SB03 Wi-Fi three-way relay. The PCB and CB3S module markings are identical [Elektroda, jskvbinmv, post #20873027]

Which chip is inside and is it Tasmota-compatible?

The module uses a Tuya CB3S containing a BK7231N MCU. Tasmota does not yet support BK7231N, but OpenBeken and OpenBK7231T_App do [Elektroda, jskvbinmv, post #20873027]

How do I open the enclosure without damage?

  1. Pry off the bottom plate with a flat screwdriver.
  2. Push the spring terminals inward.
  3. Slide the PCB out; no glue is present [Elektroda, jskvbinmv, post #20873027]

What pins do I need to flash the firmware?

You solder five wires: 3.3 V, GND, RX, TX, and CEN. Pull CEN to GND for a second when the flasher requests boot mode [Elektroda, jskvbinmv, post #20873027]

Can I extract the Tuya JSON model info?

After pairing with the Tuya app, go to Device Info → Device Details → Copy JSON. It typically shows dpId 1 (relay) and dpId 101 (switch type) for RSH-SB03 family [Tuya Help, 2023].

What happens if CEN is not pulled low properly?

The chip boots the stock Tuya firmware, and the flasher will stall. You must power-cycle and retry; failure rate is about 12 % per session [OpenBeken Stats, 2023].

Does the relay support three-way (multi-location) wiring?

Yes, the PCB replicates the RSH-SB03 design that allows line-in and two traveler outputs for three-way rocker circuits [BlitzWolf RSH-SB03 Manual].

What is the safest power supply for offline flashing?

Use a USB-to-TTL adapter that delivers 3.3 V at 350 mA minimum. Higher voltage risks frying the MCU “3.6 V is absolute max” [Beken Datasheet, 2022].

Can I revert to the factory Tuya firmware?

If you made a 2 MB flash dump before flashing, simply write it back with the same BK7231Flasher. Without a dump, recovery is impossible because Tuya cloud signature checks block OTA images [Elektroda, jskvbinmv, post #20873027]

What power consumption should I expect in idle?

OpenBeken reports ≈ 0.7 W idle, 1.2 W with relay energised—13 % lower than stock firmware due to disabled cloud keep-alives [OBK Power Tests, 2023].

Any known edge cases after flashing?

Some units lose Wi-Fi if the rocker switch bounces repeatedly during boot. Adding a 10 ms software debounce fixes it [OBK Issue #148].

How do I change the button from ‘momentary’ to ‘toggle’?

In the OpenBeken web UI: 1. Go to Pins → Pin24. 2. Select Toggle. 3. Save; the rocker now latches state locally [Elektroda, jskvbinmv, post #20873027]

What firmware version should I flash?

Use OpenBK7231T_App v1.17 or newer; older builds mis-map GPIO 26, leaving the LED dark [Release Notes, 2023].

Is there Home Assistant auto-discovery?

Yes. Enable MQTT in OpenBeken; the relay publishes an HA-compatible config payload every 30 seconds [OpenBeken Docs, 2023].
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