SEEKU WSFE-485-056 RS485 LED Display – Wiring, Modbus RTU, PC Setup & Troubleshooting
The SEEKU WSFE-485-056 is a compact industrial four-digit LED display designed to show numerical values, decimal numbers and supported text characters received from a PLC, computer or other RS485 controller.
It features a red 0.56-inch LED display, a 7–36V DC power input and an RS485 communication interface supporting Modbus RTU and ASCII display commands.
This guide covers wiring, PLC connections, PC testing with a USB-to-RS485 converter, the Modbus register map, hexadecimal command examples, signed numbers, decimal points, display brightness, communication settings and troubleshooting.
SEEKU WSFE-485-056 Overview
The WSFE-485-056 is a remote numerical indicator. It receives display information through its RS485 interface and controls the LED segments internally.
It does not independently measure temperature, voltage or current. The connected controller must acquire or calculate the required value and transmit the corresponding display command.
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | WSFE-485-056 |
| Display type | 4-digit, 7-segment LED |
| Digit size | 0.56 inch (approximately 14.2mm) |
| Display colour | Red |
| Power input | 7–36V DC |
| Typical current | Approximately 30mA |
| Communication | RS485, 2-wire half-duplex |
| Isolation | Non-isolated RS485 interface |
| Protocols | Modbus RTU and ASCII display commands |
| Supported baud rates | 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200bps |
| Overall dimensions | 79 × 43 × 21.5mm |
| Panel cut-out | 76 × 39.2mm |
Power & RS485 Connections
The display requires a DC power connection and a separate RS485 communication connection.
| Display Terminal | Function | Connection |
|---|---|---|
| V+ / Power + | Positive DC supply | External 7–36V DC positive |
| GND / Power − | DC negative and signal reference | External DC negative |
| A / 485A | RS485 differential data A | Controller or converter A |
| B / 485B | RS485 differential data B | Controller or converter B |
The RS485 interface does not power the display. Use a suitable regulated 12V or 24V DC supply for normal testing and installation.
Never connect the DC power positive terminal to RS485 A, RS485 B or a USB converter terminal. Disconnect power before changing wiring.
Non-Isolated RS485
The WSFE-485-056 uses a non-isolated RS485 interface. Its communication circuitry shares an electrical reference with its power supply.
For non-isolated installations, the RS485 devices must remain within their permitted common-mode voltage range. A suitable common signal reference or galvanically isolated interface may be required.
Do not assume equipment in separate cabinets or powered from unrelated supplies has compatible ground potentials. Use appropriately isolated RS485 equipment where significant ground differences or electrical transients may occur.
Connecting the Display to a PLC
A PLC with a compatible RS485 port and Modbus RTU master capability can control the display directly.
| SEEKU Display | PLC / Supply |
|---|---|
| V+ | External 12V or 24V DC positive |
| GND | External DC negative |
| 485A | PLC RS485 A |
| 485B | PLC RS485 B |
| Signal reference | Suitable common reference or isolation arrangement |
PLC Configuration
- Connect the display to its regulated DC supply.
- Connect the PLC RS485 A and B signals.
- Configure the PLC as a Modbus RTU master.
- Set the serial speed and frame format to match the display.
- Enter the configured slave address. The manual gives address 1 as the default.
- Use the required Modbus function and register from the register map below.
- Send a test value and check the LED display.
The hexadecimal addresses in this guide are Modbus protocol addresses. Some PLC packages use conventional holding-register numbers beginning at 40001, while others use zero-based addresses.
For example, protocol address 0x0000 may appear as holding register 40001 in a one-based numbering system. Check the addressing convention used by your PLC software.
PC Connection with a USB-to-RS485 Converter
A USB-to-RS485 converter provides a convenient way to test the display from a Windows computer without a PLC.
AuscomTech supplies a CH340 USB-to-RS485 converter with a 2-wire half-duplex interface, A/B screw terminals and Power, TX and RX indicators.
USB Converter Wiring
| Connection | Destination |
|---|---|
| Converter A | Display 485A |
| Converter B | Display 485B |
| External 12V positive | Display V+ |
| External 12V negative | Display GND |
| USB connector | Computer USB port |
The AuscomTech converter has two external RS485 terminals, A and B, but no separate signal-ground terminal. The display's interface is non-isolated.
Use this arrangement only where the RS485 common-mode voltage is within permitted limits. For a defined signal-reference connection or electrically separated industrial equipment, use a converter with suitable grounding provision or galvanic isolation.
Installing the CH340 Driver
- Connect the converter to the computer USB port.
- Open Windows Device Manager.
- Expand Ports (COM & LPT).
- Locate the USB serial converter and note its COM port number.
- If Windows does not recognise the converter, install an appropriate CH340/CH341 driver from a trusted manufacturer source.
- Reconnect the adapter and confirm that the COM port is available.
Complete Modbus Register Reference
The following table covers the Modbus registers documented in the supplied communication manual, including normal numerical display operation, persistent communication settings, brightness, flashing and advanced display functions.
Addresses are hexadecimal protocol addresses. Function 06 writes one holding register; function 10 hexadecimal (decimal 16) writes multiple holding registers.
| Register | Function | Modbus Function | Data / Range | Persistence |
|---|---|---|---|---|
0x0000 |
Display integer value | 06 | 16-bit integer display data | Display state; default has no decimal point |
0x0002 |
RS485 slave address | 06 | 1–254 (0x01–0xFE) | Saved |
0x0003 |
Baud rate | 06 | Codes 0–7 | Saved |
0x0004 |
Decimal-point position | 06 | 0–3 | Lost after power-off |
0x0005 |
Brightness | 06 | 0–7 | Saved |
0x0006 |
Flashing / flicker | 06 | 0–7 documented; 0 = off, 1 = on | Lost after power-off |
0x0070 |
ASCII character display | 10 hex | 6 registers / 12 ASCII bytes | Display data |
0x0090 |
Signed numerical value with decimal point | 10 hex | 2 registers / 4 data bytes | Display data |
Register 0x0090 is the signed-number display register and 0x0070 is the ASCII character display register. They are not registers 0x0009 and 0x0007.
Both advanced functions use Modbus function 0x10, Write Multiple Registers.
Modbus RTU – Hexadecimal Command Examples
All commands in this section use slave address 01. The last two bytes are the Modbus RTU CRC-16, transmitted low byte first.
The commands must be sent as raw hexadecimal bytes, not as ordinary ASCII text.
1. Display Integer 8888
Write decimal 8888 (hexadecimal 0x22B8) to register 0x0000.
01 06 00 00 22 B8 91 18Expected result: The LED display shows 8888.
2. Display Integer 1234
The following example writes decimal 1234 (hexadecimal 0x04D2) using the same register. Its CRC has been calculated for this value.
01 06 00 00 04 D2 0B 57Expected result: The LED display shows 1234.
3. Set One Decimal Place
Register 0x0004 sets the number of digits after the decimal point. The value 1 selects one decimal place.
01 06 00 04 00 01 09 CBFor example, if the displayed integer is 324, one decimal place represents 32.4.
| Register Value | Decimal Places | Example for 1234 |
|---|---|---|
| 0 | None | 1234 |
| 1 | One | 123.4 |
| 2 | Two | 12.34 |
| 3 | Three | 1.234 |
The manual states that register 0x0004 loses its setting after a power interruption. The default is no decimal point. The controller should resend the required decimal-point setting after the display powers up.
4. Change Slave Address to 2
Register 0x0002 controls the RS485 station address. This example changes the address from 1 to 2.
01 06 00 02 00 02 A9 CBExpected result: The display accepts the address-change command. Future commands must use slave address 02.
This changes a saved setting. Do not send it during normal display-value testing. After changing the address, subsequent commands addressed to 01 may no longer communicate with the display.
The manual documents address values from 0x01 to 0xFE and gives 0x01 as the default.
5. Configure 9600 Baud
Register 0x0003 sets the serial baud rate using a numeric code. The code for 9600bps is 3.
01 06 00 03 00 03 39 CBThis command assumes the display's current address is 1. Transmit it at the display's current baud rate, then configure the controller to communicate at 9600bps after the setting takes effect.
Baud Rate Register Codes
| Register Value | Baud Rate |
|---|---|
| 0 | 1200bps |
| 1 | 2400bps |
| 2 | 4800bps |
| 3 | 9600bps |
| 4 | 19200bps |
| 5 | 38400bps |
| 6 | 57600bps |
| 7 | 115200bps |
The manual states that the baud-rate parameter is saved permanently and gives code 3 (9600bps) as the default.
6. Set Maximum Brightness
Register 0x0005 controls brightness. Valid values are 0–7, where 0 is darkest and 7 is brightest.
01 06 00 05 00 07 D8 09Expected result: The display changes to brightness level 7. The manual identifies this as the default and states that the setting is retained after power-off.
7. Enable Display Flashing
Register 0x0006 controls the display flashing function.
01 06 00 06 00 01 A8 0BExpected result: The display flashes.
The manual identifies value 0 as flashing disabled and value 1 as flashing enabled. It also lists a value range of 0–7, but does not clearly define all intermediate behaviours. Use 0 and 1 for basic on/off control.
The flashing setting is temporary and defaults to off after power is removed.
Advanced Modbus Display Functions
Besides ordinary integer display, the module supports signed numerical values, decimal positions and ASCII character display using Modbus function 0x10.
Register 0x0090 – Signed Number with Decimal Point
This operation writes two consecutive holding registers starting at address 0x0090. The data payload contains four bytes:
| Byte Position | Function |
|---|---|
| Byte 1 | Sign: 0 = positive, 1 = negative |
| Byte 2 | Decimal places: 0, 1 or 2 |
| Bytes 3–4 | 16-bit numerical value, high byte first |
The numerical value is interpreted using the selected decimal-place setting. For example, raw decimal 490 with two decimal places represents 4.90.
Example – Display 4.90
01 10 00 90 00 02 04 00 02 01 EA DB 1CCommand breakdown:
| Bytes | Meaning |
|---|---|
| 01 | Slave address 1 |
| 10 | Write Multiple Registers |
| 00 90 | Starting register 0x0090 |
| 00 02 | Write two registers |
| 04 | Four data bytes |
| 00 | Positive number |
| 02 | Two decimal places |
| 01 EA | Decimal 490 |
| DB 1C | CRC-16 |
Expected result: The LED displays 4.90.
Example – Display -1.0
01 10 00 90 00 02 04 01 01 00 0A 2A F8Here, the first data byte selects a negative number, the second data byte selects one decimal place and the numerical data represents 10.
Expected result: The display shows -1.0.
Example – Display 0.2
01 10 00 90 00 02 04 00 01 00 02 2A C2Expected result: The display shows 0.2.
Select Modbus function 16 decimal (0x10 hexadecimal), starting register address 0x0090, with two registers and four bytes of data.
Do not use function 06 for this operation. The signed-number format requires the complete four-byte payload.
Register 0x0070 – Display ASCII Characters
The ASCII-character display function uses Modbus RTU function 0x10 to write six consecutive holding registers starting at address 0x0070.
The payload contains 12 bytes of ASCII character data. The manual shows text beginning at the left side of the display, with excess character positions filled using zero bytes.
Example – Display P2.3
01 10 00 70 00 06 0C
50 32 2E 33 00 00 00 00 00 00 00 00
3B 25Data interpretation:
| ASCII Hex | Character |
|---|---|
| 50 | P |
| 32 | 2 |
| 2E | Decimal point (.) |
| 33 | 3 |
| 00 | Unused / padding positions |
Expected result: The display shows P2.3 using the available seven-segment character representations.
This is different from the separate ASCII communication protocol. The ASCII character-display operation uses Modbus function 0x10, register 0x0070 and a binary Modbus RTU frame with CRC.
The seven-segment display cannot reproduce every alphabetic character exactly as it appears on a computer screen.
Separate ASCII Communication Protocol
In addition to Modbus RTU, the communication manual describes a manufacturer-specific ASCII command protocol.
This protocol uses printable characters to communicate with the display. It is distinct from the Modbus RTU multi-register ASCII-character operation described above.
Basic ASCII Display Command
The manual provides an address-prefixed display command using dollar-sign and hash-sign framing.
$001,1234#In this command:
| Part | Meaning |
|---|---|
$ | Command start |
001 | Display address 1 |
, | Address/data separator |
1234 | Display content |
# | Command terminator |
Expected result: The display shows 1234 when configured to recognise this ASCII command format and address.
ASCII Display Capabilities
The manual describes commands for display data, address modification, brightness adjustment, software-version information and control/status queries.
Because these commands can affect stored configuration, use the exact syntax specified for the relevant operation. Avoid sending guessed command variations.
For a Modbus RTU command, send raw binary bytes with the correct CRC. For the manufacturer's ASCII display command, send the literal printable command characters.
A text terminal cannot generate a Modbus RTU frame simply by typing hexadecimal characters separated by spaces.
Practical PC Test – USB-to-RS485
The easiest way to check display operation without a PLC is to use a suitable USB-to-RS485 converter and a Modbus RTU master application.
Step 1 – Connect the Hardware
- Disconnect power while connecting the display.
- Connect the USB converter A and B terminals to the corresponding display terminals.
- Connect the display to its external regulated DC supply.
- Ensure the installation has a suitable RS485 electrical reference.
- Connect the USB converter to the computer.
Step 2 – Configure the Serial Connection
Use a Modbus RTU master application such as QModMaster or other suitable industrial Modbus testing software.
| Parameter | Initial Setting |
|---|---|
| Mode | Modbus RTU |
| Serial port | Converter COM port |
| Slave address | 1 (manual default) |
| Baud rate | 9600bps (manual default) |
| Data bits | 8 |
| Parity | None |
| Stop bits | 1 |
If the display has previously been configured, use its current stored settings instead.
Step 3 – Write a Test Display Value
- Select slave address 1.
- Select function 06, Write Single Holding Register.
- Enter register address 0x0000 using the addressing convention of the software.
- Enter decimal value 1234.
- Send the command.
- Observe the LED display.
Expected Result
The display should show 1234. If the application reports a response, confirm the response is valid and that the display has actually changed.
As a second test, write decimal 8888 to the same register. The display should update to 8888.
Testing with Raw Hexadecimal Software
Some serial diagnostic applications allow raw hexadecimal transmission rather than a conventional Modbus register interface.
For display 8888, transmit:
01 06 00 00 22 B8 91 18Ensure the application is set to transmit hexadecimal bytes, not the literal character string shown above. Do not append carriage-return or line-feed characters to a Modbus RTU frame.
Local Configuration & Communication Settings
The communication manual also describes a local configuration system using two control switches on the rear circuit board.
Configuration Switches
The manual identifies:
- SW1: Menu / configuration selection
- SW2: Down / parameter adjustment
The configuration interface allows the operator to navigate through normal display operation, address, baud rate, protocol, brightness and save options.
Follow the switch labels and menu indications on the supplied unit. Do not short unrelated PCB contacts or assume that every hardware revision uses the same switch arrangement.
Reported Menu Sequence
| Menu Example | Meaning |
|---|---|
1234 | Normal numerical display |
A001 | Station address 1 |
96 | 9600 baud display setting |
d-0 | Protocol setting, shown in the manual example |
b-7 | Brightness setting |
YES | Save configuration |
Changing the Station Address
The default address stated in the manual is 1. Address values from 1 to 254 are documented.
- Record the current station address.
- Enter the local configuration menu using the documented switches.
- Navigate to the address parameter.
- Select a unique address for the RS485 network.
- Confirm and save the parameter as required.
- Reconfigure the PLC or PC software for the new address.
Changing the Baud Rate
The manual gives 9600bps as the default and supports the following settings:
| Baud Rate | Modbus Register Code |
|---|---|
| 1200 | 0 |
| 2400 | 1 |
| 4800 | 2 |
| 9600 | 3 |
| 19200 | 4 |
| 38400 | 5 |
| 57600 | 6 |
| 115200 | 7 |
When the baud rate changes, the controller must also be configured for the new speed.
Brightness Configuration
The Modbus brightness register supports levels 0–7, with 7 as the brightest setting. The manual gives level 7 as the default.
The brightness value is retained after a power interruption.
Temporary Versus Saved Settings
| Parameter | Power-Cycle Behaviour |
|---|---|
| Slave address | Saved |
| Baud rate | Saved |
| Brightness | Saved |
| Decimal-point setting | Resets to no decimal point |
| Flashing setting | Resets to flashing disabled |
For applications requiring a fixed decimal-point position or flashing behaviour, configure the controller to resend those temporary settings after power-up.
Industrial RS485 Installation Notes
Cabling
- Use suitable twisted-pair cable for RS485 A and B.
- Prefer daisy-chain wiring over long star-shaped branches.
- Keep communication wiring away from high-current motor and mains wiring where practical.
- Provide suitable signal reference or isolation between devices.
- Keep branch cables short.
Termination
Longer RS485 cable runs commonly require termination at the two physical ends of the bus. A typical termination value is 120 ohms when matched to the cable and transceivers.
Do not fit termination resistors across every connected display. Excess termination can overload the RS485 drivers.
Multiple Displays
Multiple displays can share an RS485 bus when configured with appropriate addressing.
Each independently controlled display should have a unique station address. Ensure the Modbus master addresses the intended device and that only one master drives the bus at a time.
Troubleshooting
Display Does Not Power On
- Measure the voltage directly at V+ and GND.
- Confirm the power supply is within 7–36V DC.
- Check supply polarity.
- Inspect wiring and terminal connections.
- Check that the supply has sufficient capacity.
Display Powers Up but Does Not Respond
- Confirm RS485 A and B wiring.
- Check that the controller and display use matching baud rates.
- Verify the slave address.
- Check the protocol mode.
- Confirm the transmitted Modbus frame includes a valid CRC.
- Check the electrical reference and common-mode limits of the RS485 interface.
Modbus Write Does Not Change the Display
- For ordinary integers, use function 06 and register 0x0000.
- Check whether the PLC uses zero-based or one-based register numbering.
- Confirm the transmitted numerical value is correct.
- Check that the display is addressed correctly.
- Try the documented 8888 command using a compatible raw hexadecimal tool.
- Verify that the correct communication protocol is selected.
Signed Numbers or Decimal Points Are Wrong
- Use register 0x0090 with function 0x10 for the documented signed-number format.
- Check the sign byte: 0 for positive, 1 for negative.
- Check the decimal-place byte.
- Verify the two-byte numerical value is transmitted high byte first.
- For ordinary unsigned integer display, check register 0x0004 for decimal-point positioning.
- Remember that the ordinary decimal-point setting resets after power-off.
ASCII Text Does Not Display Correctly
- For ASCII character display through Modbus RTU, use starting register 0x0070.
- Select function 0x10, Write Multiple Registers.
- Send six registers containing 12 data bytes.
- Check the ASCII character values and unused padding bytes.
- Remember that seven-segment displays cannot reproduce every letter exactly.
- Do not confuse this operation with the separate ASCII serial protocol.
Slave Address Changed Unexpectedly
- Check whether a previous command wrote to register 0x0002.
- Inspect the current station address using the local configuration interface.
- Reconnect the Modbus master using the new address.
- Record the correct address before returning the display to service.
USB-to-RS485 Converter Is Not Detected
- Check the computer USB port.
- Inspect Ports (COM & LPT) in Device Manager.
- Install an appropriate CH340/CH341 driver if required.
- Confirm no other software is using the COM port.
- Reconnect the converter and check its assigned COM port.
TX LED Flashes but the Display Does Not Update
- TX activity shows that data is being transmitted, not that the display accepted it.
- Check the A/B terminal connections and polarity.
- Verify the display power supply.
- Confirm the baud rate, station address and function code.
- Check the RS485 electrical reference and common-mode requirements.
- Use a suitable analyser or Modbus diagnostic tool when necessary.
Communication Is Intermittent
- Check connector tightness and cable continuity.
- Use suitable twisted-pair cabling.
- Keep communication wiring away from electrical interference.
- Check bus termination and biasing.
- Reduce the baud rate if appropriate.
- Consider galvanic isolation for electrically noisy or distributed installations.
The SEEKU WSFE-485-056 is an industrial LED display requiring a regulated 7–36V DC supply. Its non-isolated RS485 interface must be installed with suitable grounding, electrical protection and isolation where required.
The Modbus registers and hexadecimal commands in this guide are transcribed from the supplied communication manual for this display type. Firmware and hardware revisions may differ. Always check the terminal markings, configured address and communication parameters of the actual unit before performing configuration writes.
Registers 0x0002, 0x0003 and 0x0005 change saved settings. Use these commands only when intentionally configuring the device. Disconnect power before changing wiring and verify operation before returning industrial equipment to service.