D3J0104 Modbus
A 4-channel isolated Modbus-RTU/RS-485 digital input module for distributed status monitoring.
🔍 Click to enlarge · 1/3Technical Specifications
| Ordering code | D3J0104 (default M1: RS-485 only, no wireless) |
|---|---|
| Product identification code / default slave address | 0x3104 |
| Inputs | 4-channel fully isolated digital input, plus 2 analog inputs and 1 x 5V/100mA sensor supply |
| Outputs | None - pure input module, no relay or transistor output |
| Communication interface | RS-485 (Modbus-RTU, default 9600/8-Even-1); optional 2.4GHz wireless |
| Supply voltage | DC 11-28V |
| Physical interface | RS-485 half-duplex, differential A/B pair; built-in USB port; optional 2.4GHz wireless MODBUS-OTA |
| Communication protocol | MODBUS-RTU (primary); MODBUS-ASCII and AT commands also supported; wireless MODBUS-OTA optional |
| Default baud rate | 9600bps |
| Default data format | 8 data bits, even parity, 1 stop bit |
| Default slave address | 0x02 |
| Optional baud rates | 300 / 600 / 1200 / 1800 / 2400 / 4800 / 7200 / 9600 / 14400 / 19200 / 28800 / 38400 / 56000 / 57600 / 76800 / 115200 |
| Optional parity | None / odd / even (default even) |
| Optional stop bits | 1 (default) / 1.5 / 2 |
| Slave address range | 1-247 (0x01-0xF7) |
| USB mode address | Fixed 0x01 when USB is connected; RS-485 then switches to master mode |
| Input threshold | Approx. 3V (above = high level, below = low level) |
| Input edge counting | Per-channel DINnCNT register increments on rising edge; pulse frequency up to 5Hz; rolls over at 65535; clearable by write |
| Input filter | Per-channel DINnFLT, adjustable 1-65535ms (0 = off); savable to non-volatile memory by writing MODESAVE = "MS" |
| Auto reporting | Supports interval-based or change-triggered reporting (AT format, via USB or RS-485); off by default |
| Supported function codes | 0x02 read discrete inputs, 0x04 read input registers, 0x03 read holding registers, 0x06 write single holding register, 0x10 write multiple holding registers, 0x16 mask write, 0x17 read/write multiple holding registers, 0x11 report device identification |
| Exception codes | 0x01 ENOFUNC (unsupported function code), 0x02 ENOADR (address/quantity out of range), 0x03 EINVAL (invalid length or field), 0x04 EDEVICE (execution error, e.g. writing an illegal value) |
| Configuration protection | Sensitive registers (NAME/SRLCFG/wireless config, etc.) require writing ASCII "UL" (0x554C) to SAFELCK (0x000E) to unlock; SAFELCK re-locks automatically after each write, or if a bus parity/CRC error occurs or a command targets another module |
| Supply ripple | < 1Vp-p |
| Supply current | < 1500mA |
| Communication port stress (normal) | DC 0-5V |
| Input stress (normal) | DC 0-30V |
| Communication isolation voltage (normal) | < 250V |
| Input isolation voltage (normal) | < 250V |
| Operating temperature | -20 to 60°C |
| Supply voltage (absolute maximum) | DC 28V |
| One-time fuse | DC 250V, 3000mA, slow-blow |
| Communication port stress (absolute maximum) | DC 50V |
| Input stress (absolute maximum) | DC 50V |
| Communication isolation voltage (absolute maximum) | DC 1000V, 60s (type test only) |
| Input isolation voltage (absolute maximum) | DC 1000V, 60s (type test only) |
| Storage temperature | -40 to 85°C |
| ESD immunity | IEC 61000-4-2: 4kV discharge on all terminals - normal operation (A) |
| EFT immunity | IEC 61000-4-4: 2kV/5kHz/2min - normal operation (A); 4kV/5kHz/2min - no permanent damage (C) |
| Surge immunity | IEC 61000-4-5: 1kV terminal-to-ground - no permanent damage (C) |
| Creepage distance | > 6.5mm measured (requirement > 6mm), pollution degree 3, material group IIIa/IIIb, per IEC 60950-2L/2N |
| Electrical clearance | > 2.2mm measured (requirement > 2mm), per IEC 60950-2H |
| Input response time | Typical 20ms |
| Serial command reply time | Maximum 25ms |
| Module dimensions (4-channel) | 54 x 88 x 59mm (tolerance ±5%) |
| Terminal pitch | 5.08mm |
| Terminals and indicators (4-channel) | 8 screw terminals, 2 analog ports, 1 USB port, 5 indicator LEDs (4 input indicators + 1 power indicator) |
Overview
The D3J0104 is a 4-channel isolated Modbus-RTU/RS-485 digital input module built around a dedicated ASIC, the 4-channel member of the D3J01 series (4/8/16/28-channel versions are distinguished by input count). It is a pure-input device: it only reads external digital signals and reports them to a host controller over RS-485, with no relay or transistor output of any kind - it suits engineers who need to add a few scattered digital status points, such as limit switches, proximity switches or dry contacts, onto a Modbus/RS-485 bus without wiring them back to one large central module.
Each of its 4 fully isolated inputs has its own rising-edge counter (pulse frequency up to 5Hz, rolls over at 65535, clearable by write) and an adjustable input filter (1-65535ms, savable to non-volatile memory), so debouncing happens in hardware instead of host software. Besides RS-485 Modbus-RTU (default 9600bps, 8 data bits, even parity, 1 stop bit), the module includes a USB port for configuration or USB-to-serial operation, supports MODBUS-ASCII and AT commands, and can be ordered with an optional 2.4GHz wireless MODBUS-OTA link. It also carries 2 extra analog input channels and a 5V/100mA sensor supply, so one board covers a handful of digital points plus light analog measurement.
Features & Benefits
One Small Module Per Point Instead of One Long Cable Run
At 54 x 88 x 59mm the D3J0104 drops into the machine's own junction box or a small sub-panel, so 4 nearby signals are digitised on the spot and only a twisted pair goes back to the control room. Compared with hauling long individual signal cables to one big central rack, that cuts copper, keeps low-level contact wiring short, and confines any single-point failure to 4 channels instead of taking down a whole 28-channel card. When a location later grows, the 8/16/28-channel D3J0108/D3J0116/D3J0128 use the same protocol and register map.
2kV EFT Immunity - Twice the Industrial Requirement
IEC 61000-6-2-2016 asks industrial equipment to survive 1kV of electrical fast transients; the D3J0104 stays in normal operation (criterion A) at 2kV/5kHz for 2 minutes and takes no permanent damage even at 4kV. ESD testing is 4kV on all terminals and surge is 1kV terminal-to-ground. That margin is what keeps status bits from flickering when a contactor or VFD beside the box switches an inductive load. For sites with especially frequent EFT events, the input-reinforced 'XS' suffix hardens the input stage further.
Every Input and the RS-485 Port Are Galvanically Isolated
All 4 digital inputs and the RS-485 port are isolated from internal logic - under 250V in normal use, type-tested at DC 1000V for 60 seconds - so a ground-potential difference between a distant machine and the control room cannot travel down the bus. The supply adds reverse-polarity, over-current, surge and automotive load-dump protection behind a DC 250V/3000mA slow-blow fuse. Creepage measures over 6.5mm against the 6mm required at pollution degree 3, and clearance over 2.2mm against 2mm, achieved with slots cut into the PCB on the high-voltage side.
Debounce and Pulse Counting Done in Hardware, Not in Your PLC Code
Every channel carries its own DINnFLT filter, adjustable from 1 to 65535ms (0 = off) and saved to non-volatile memory by writing MODESAVE = "MS", so a chattering limit switch is cleaned up at the module and the setting survives a power cut. Each channel also has a DINnCNT rising-edge counter (up to 5Hz, rolling over at 65535, clearable by write), so cycle counts keep accruing between polls and you never write a debounce timer or an edge-detect rung on the host.
Drops Straight Into Any Modbus Master - No Driver, No Development
Read the 4 inputs as discrete inputs with function code 0x02; 0x04, 0x03, 0x06, 0x10, 0x16, 0x17 and 0x11 are supported too, and the module returns proper exception codes rather than going silent. Input response is typically 20ms and a reply arrives within 25ms, so poll rates are predictable. MODBUS-ASCII suits touchscreens and older PLCs, AT commands cover quick one-off setups, and optional interval-based or change-triggered auto-reporting lets the module push updates instead of waiting to be polled.
The Built-In USB Port Replaces the RS-485 Converter You Would Otherwise Buy
A USB port is standard on every unit and doubles as a USB-to-serial adapter, so a laptop configures the module or talks to the bus without a separate dongle. Plug USB in and the module's address is fixed at 0x01 while its RS-485 port flips to master mode - meaning the module itself can drive and interrogate the bus for bench testing or commissioning before the PLC is even wired.
SAFELCK Keeps a Noisy Bus From Rewriting Your Configuration
Sensitive registers such as NAME, serial configuration and the wireless keys cannot be touched until ASCII "UL" (0x554C) is written to SAFELCK at 0x000E, and the lock re-arms automatically after every single write. It also re-arms if the bus throws a parity or CRC error, or if a command addressed to another module goes past - so line noise or a mis-addressed write cannot silently change a commissioned module's baud rate or slave address and drop it off the network.
Bonus Analog Inputs and a 5V Sensor Supply Already On Board
Two extra analog channels read at 1mV per bit with roughly 10-bit resolution and 3% typical accuracy in range, available at input registers 0x0020 and 0x0021, plus a VCC5V output that powers a small sensor at 5V/100mA. A point needing 4 dry contacts and one soil-moisture or level sensor is covered by one module and one bus drop instead of two devices. These leads sit inside the housing and must be brought out on dedicated wires, and unlike the digital inputs they are not isolated.
Applications
Models & Ordering Information
D3J0104 (4-Channel Input)
How to Select
- Choose the 4-channel D3J0104 when each location has few signal points (up to 4) but locations are geographically scattered - distributing several 4-channel modules saves wiring, resists interference better and limits the impact of any single-point fault compared with running long cable back to one large module.
- Move up to the 8-channel D3J0108 or 16-channel D3J0116 when a single location has more input points.
- Choose the 28-channel D3J0128 when dozens of signals are concentrated in one panel or cabinet.
- Add the optional 2.4GHz wireless version where wiring is difficult or the installation is temporary.
- Order the input-reinforced 'XS' suffix for locations with frequent EFT events or inductive-load switching.
- Use RS-485 for long runs, multi-drop networking and noisy environments; use the built-in USB port for local configuration or as a USB-to-serial link.
- Remember the module is pure input - if the application also needs a relay or transistor output, choose a D3J02 or D3J03 series module instead.
📘 Need the full method? NPN vs PNP Sensor Outputs Explained
When NOT to specify the D3J0104 — and what to use instead
The application needs to switch something - a contactor, indicator, valve, or pump - not just report a signal.
Why not: D3J0104's own spec lists its outputs as 'None - pure input module, no relay or transistor output'; there is no output register, relay, or transistor stage on the board at all.
Use instead: D3J0302 (2 isolated inputs + 1 output) for combined input+output on one board, or D3J0202 (2-channel output) if only outputs are needed.
The location actually has more than 4 signal points to bring onto the bus.
Why not: D3J0104's own spec fixes its input count at '4-channel fully isolated digital input' - there is no way to add a 5th channel on this board.
Use instead: D3J0108 (8 inputs), D3J0116 (16 inputs), or D3J0128 (28 inputs), depending on how many points the location actually has.
The signal is part of a machine safety function - an emergency-stop circuit, a safety door interlock, a light-curtain OSSD, or a two-hand control input.
Why not: D3J0104 carries no Type/SIL/PL rating anywhere in its specification. Its digital inputs trip at an ordinary ~3V threshold and are only rated for normal DC 0-30V terminal stress and <250V basic isolation (type-tested to DC 1000V/60s) - nothing qualifies any input as an OSSD or a safety-rated channel, and the module has no dual-channel safety logic or forced-guided contact monitoring.
Use instead: DA31 Emergency-Stop Safety Relay Module (Cat.4/PL e/SIL 3) or DQSRN Safety Relay Module (DIP-switch selectable E-stop/OSSD/door-interlock/two-hand, Cat.4/PL e/SIL 3).
The host system communicates over Ethernet/EtherCAT, PROFIBUS, CANopen, or another fieldbus rather than serial Modbus.
Why not: D3J0104's only communication paths are RS-485 running Modbus-RTU (default 9600bps, 8 data bits, even parity, 1 stop bit), plus Modbus-ASCII, AT commands, a USB port, and an optional 2.4GHz wireless Modbus-OTA link - no other fieldbus stack is listed in its specification.
Use instead: No module in the D3J01/D3J02/D3J03/D4G0206 lineup speaks anything but Modbus-RTU/ASCII; pair the module with a separate Modbus-to-fieldbus gateway if the host requires a different protocol.
The signals need to drive a local action by themselves, without a PLC or SCADA host doing the polling and decision-making.
Why not: D3J0104 only exposes its input states to whatever master polls it over Modbus-RTU (or, if enabled, pushes them via interval/change-triggered auto-reporting) - it has no ladder logic, no local decision engine, and no output of any kind to act on a decision.
Use instead: D4G0206 Relay Module, a graphical schematic-programmed micro-PLC with 6 inputs and 4 relay/transistor outputs that runs its own logic without a host.
Specifications we do not publish yet
We only publish a figure once we are confident it is true. The items below are still being validated through further testing and real-world customer feedback, so for now we would rather leave them open than guess. If one of them matters to your design, ask us for the latest validated status.
- Ingress protection (IP) rating for the D3J0104 enclosure is not stated in the source specification.
- MTBF or expected service life for D3J0104 is not stated in the source specification.
- Terminal wire gauge (AWG/mm²) accepted by D3J0104's 5.08mm-pitch screw terminals is not stated in the source specification.
- Per-channel input current draw for D3J0104 is not stated - only total supply current (<1500mA) is given in the source specification.
- Maximum number of RS-485 nodes per bus segment and maximum cable length for D3J0104 are not stated in the source specification.
- A radiated/conducted EMC emission standard for D3J0104 is not stated - the source specification only lists ESD/EFT/surge immunity test levels.
- Module weight for D3J0104 is not stated - only the 54 x 88 x 59mm dimensions are given in the source specification.
Frequently Asked Questions
What is the D3J0104 used for?
Does the D3J0104 have any relay or digital output?
How many D3J0104 modules can share one RS-485 bus?
Can I configure the module over USB instead of RS-485?
How do the edge counting and input filter functions work?
What are the extra analog inputs and 5V output for?
Does the D3J0104 meet industrial EMC and safety requirements?
Works Well Together
On the same machine or line, D3J0104 is typically ordered together with: Proximity Sensors · Photoelectric Sensors · Laser Distance Sensors
D6.5 Series Inductive Proximity Sensors (Ultra-Short 18mm / Y-Type / 35mm / 45mm)
6.5mm-diameter inductive proximity sensors for tight-clearance mounting where M8 sensors won't fit.
BGS-CX441 / BGS-CX442 Background Suppression Photoelectric Sensor
Wire-adjustable BGS sensor with 2 mm or 15 mm spot, 10-300 mm range, published black/white differential distance.
DDA-Y & DDB-Y Industrial Laser Distance Sensor (Phase-Shift)
Phase-shift laser distance sensors: 0.2-100 m range, millimeter accuracy, RS485 Modbus RTU, switching or analog output.
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