D3J0304 Modbus
A 4-in/2-out isolated Modbus-RTU/RS-485 digital I/O module that acquires and controls on one board.
🔍 Click to enlarge · 1/3Technical Specifications
| Ordering code | D3J0304M111 (default: all-relay output, pulse unavailable, no wireless) |
|---|---|
| Product identification code / default slave address | 0x3304 |
| Inputs | 4-channel fully isolated digital input, plus 2 analog inputs and 1 x 5V/100mA sensor supply |
| Outputs | 2-channel digital output (relay or transistor selectable), plus up to 2 pulse PWM/PTO outputs |
| 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 |
| Series input channels | Up to 12 fully isolated digital inputs across the D3J03 series (2/4/8/12-channel models) |
| Series output channels/type | Up to 8 fully isolated digital outputs across the D3J03 series (1/2/4/8-channel models); relay or transistor selectable, default all-relay output |
| 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; rolls over at 65535; clearable by write |
| Input filter | Per-channel DINnFLT anti-jitter filter, adjustable (0 = off); savable to non-volatile memory |
| Auto reporting | Supports interval-based or change-triggered reporting (AT format, via USB or RS-485); off by default |
| Reading inputs / writing outputs | Digital inputs read with function code 0x02 (read discrete inputs); digital outputs written/read via holding registers (0x03/0x06/0x10) on DOUTnDV and related registers; also supports 0x04 read input registers, 0x16 mask write, 0x17 read/write multiple registers, 0x11 report device identification |
| Configuration protection | Sensitive registers (name/serial port/wireless configuration, etc.) require writing ASCII "UL" to the safety-lock register to unlock; the register re-locks automatically after each write |
| Output direct drive | Host writes DOUTnDV to directly control relay/transistor on/off; output polarity invert and coil force are configurable |
| Jog / delay output modes | 5 delay (jog) modes - output connects automatically once the trigger condition is met and disconnects after a configurable delay; delay time unit and value are configurable |
| Input-linked output | Each digital output can be triggered by the same-numbered digital input's level (output n <-> input n) with no host intervention required |
| Emergency brake | Limit/e-stop inputs can force outputs to a preset safe value via the brake flag register (BRKFLG), with priority over port force and no host intervention required |
| Pulse outputs | Up to 2 high-speed pulse outputs for standard PWM speed control or PTO stepper/motor drive (segmented PGM program); a fast-PWM channel (FPWM0PRD period / FPWM0DTY duty cycle) is available for precise quantitative control, e.g. heating elements |
| Supply ripple | < 1Vp-p |
| Supply current | < 1500mA |
| Communication port stress (normal) | DC 0-5V |
| Input stress (normal) | DC 0-30V |
| Output stress, relay type (normal) | DC 30V or AC 0-220V, 8A |
| Output stress, standard transistor type (normal) | DC 12-48V, 8A |
| Output stress, high-speed transistor type (normal) | DC 12-24V, 8A |
| Communication isolation voltage (normal) | < 250V |
| Input isolation voltage (normal) | < 250V |
| Output isolation voltage (normal) | Relay type < 250V; transistor type < 130V |
| Operating temperature | -20 to 60°C |
| Isolation note | The RS-485 communication port, all digital inputs and all digital outputs are electrically isolated from the internal logic; the USB port and analog inputs are not isolated |
| 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 |
| Output stress, relay type (absolute maximum) | DC 30V or AC 0-220V, 8A |
| Output stress, standard transistor type (absolute maximum) | DC 55V, 10A |
| Output stress, high-speed transistor type (absolute maximum) | DC 40V, 10A |
| Communication / input isolation voltage (absolute maximum) | DC 1000V, 60s (type test only) |
| Output isolation voltage (absolute maximum) | Relay type DC 1000V, 60s; transistor type DC 250V, 60s (type test only) |
| Transistor output characteristics | Open-drain connection; standard/high-speed FET rated DC 12-48V, tolerates 10A, with a built-in 10A flyback diode able to directly drive 10A inductive loads (solenoids, motors); brief mis-conduction of about 100ms may occur during power on/off transitions - recommended sequencing is module power-on before the outputs and power-off after the outputs |
| Relay mechanical life | Over 100,000 cycles (over 10,000 cycles under heavy load, varies by load) |
| 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, relay terminal to logic side basic insulation, per IEC 60950-2L/2N |
| Electrical clearance | > 2.2mm measured (requirement > 2mm), per IEC 60950-2H |
| Input/output response time | Typical 20ms |
| Serial command reply time | Maximum 25ms |
| Module dimensions (4-in/2-out) | 72 x 88 x 59mm (tolerance ±5%) |
| Terminal pitch | 5.08mm |
| Screw terminals (4-in/2-out) | 14 |
| Terminals and indicators | Power +/- terminals, USB port, digital input +/- terminals per channel (adjacent channels share a common negative), per-output NC/COM/NO relay terminals (or load/load-power common + load negative for transistor type), VCC5V output, 2 analog input ports, GND, per-channel input indicator LEDs, 1 power indicator LED |
Overview
The D3J0304 is a 4-input/2-output isolated Modbus-RTU/RS-485 digital I/O module built around a dedicated ASIC, the 4-in/2-out member of the D3J03 series (D3J0302/04/08/12, distinguished by input/output count). Unlike a pure-input or pure-output module, it combines acquisition and control on one board: a host reads 4 fully isolated digital inputs while independently controlling 2 relay or transistor outputs over the same RS-485 bus, so it suits engineers building small machines or control cabinets who need a compact 'read a few points, drive a couple of loads' module instead of wiring two separate I/O boards.
Each output can be driven directly from the host, supports five jog/delay modes, and can also be locally linked to the same-numbered input (output n <-> input n) or forced to a preset safe value by an emergency-brake function, so basic interlock logic keeps working even if the host goes offline, with a typical response time of 20ms. Besides RS-485 Modbus-RTU (default 9600bps, 8 data bits, even parity, 1 stop bit, slave address range 1-247), 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, plus 2 analog input channels, up to 2 high-speed pulse outputs (PWM speed control or PTO motor drive) and a 5V/100mA sensor supply.
Features & Benefits
One Board Replaces an Input Card Plus an Output Card
4 fully isolated digital inputs and 2 digital outputs sit on the same 72 x 88 x 59mm housing with 14 screw terminals at 5.08mm pitch. The host reads limit switches, e-stops, push buttons and dry contacts while driving 2 loads over the same RS-485 pair - one slave address, one bus drop, one DIN-rail footprint instead of two separate modules and two sets of wiring.
Interlocks Survive a Dead Host
Output n can be linked to input n so it follows that input's level with zero host traffic, and a limit or e-stop input can force outputs to a preset safe value through the brake register BRKFLG, which outranks port force and direct-drive commands. Typical I/O response is 20ms, so the interlock reacts on the module rather than at the mercy of your poll rate or a stalled PLC scan.
Relay or FET Output - Pick the One Your Load Needs
The default relay version switches DC 30V or AC 0-220V at 8A for contactors, lamps and heaters, with mechanical life over 100,000 cycles. Order the FET version instead and you get an open-drain output rated DC 12-48V with a built-in 10A flyback diode, driving solenoid valves and small motors up to 10A directly - no external suppression diode to source, size and mount.
Five Jog/Delay Modes Take Timing Off the Host
Every output has five delay (jog) modes with configurable time unit and value: once the trigger condition is met the output closes and re-opens on its own after the set delay. Simple cycle timing, pulse actions and auto-stop live in the module, so a small station needs no timing ladder logic and no dedicated timer relay next to it.
Debounce and Counting Done in Hardware
Each input carries its own DINnCNT rising-edge counter that rolls to zero at 65535 and can be cleared by a write, plus a DINnFLT anti-jitter filter that is independently adjustable (0 disables it) and survives power loss once saved. You count product on a photo sensor or filter a chattering contact without burning host cycles or losing edges between polls.
Every Field Port Is Isolated, and the EFT Margin Is Doubled
RS-485, all digital inputs and all digital outputs are electrically isolated from the internal logic (< 250V), each with its own reverse-polarity and surge protection, and the supply survives reverse connection, overcurrent, surge and automotive load-dump. EFT immunity is 2kV - twice the 1kV that IEC 61000-6-2-2016 asks of industrial equipment - with 4kV ESD tested and -20 to 60C operation. Certification documents are available on request.
Creepage Measured at 6.5mm, Not Just Claimed
The PCB is slotted on the high-voltage side so the relay terminals reach > 6.5mm creepage to the logic side against a > 6mm requirement, and > 2.2mm clearance against a > 2mm requirement, at pollution degree 3 with material group IIIa/IIIb per IEC 60950. That is the detail that lets you put AC 220V contactor wiring and RS-485 signal wiring in the same enclosure without an argument at inspection.
Standard Modbus, Plus a USB Port and Three Bonus Channels
Modbus-RTU at 9600/8-Even-1 out of the box, baud rates 300 to 115200, address 1-247, function code 0x02 for inputs and 0x03/0x06/0x10 for outputs - it drops straight into any PLC, HMI or SCADA. The on-board USB port configures the module without a 485 converter (address fixed 0x01, RS-485 flips to master) and also works as a USB-to-serial adapter, while 2 analog inputs, up to 2 PWM/PTO pulse outputs and a 5V/100mA sensor supply come along at no extra module. Sensitive registers are protected by an ASCII "UL" safety lock that re-arms after every write.
Applications
Models & Ordering Information
D3J0304 (4-Input / 2-Output)
How to Select
- Choose the D3J0304 when a machine or panel needs 3-4 input points and 1-2 output channels on one board - 14 screw terminals and a ~72mm length balance point count and physical size.
- Move down to the 2-in/1-out D3J0302 for single- or dual-point detection with a single drive channel.
- Move up to the 8-in/4-out D3J0308 or 12-in/8-out D3J0312 when a larger cabinet needs more input or output points.
- Choose the transistor-output variant for inductive or high-current loads such as solenoids or small motors up to 10A; keep the default relay-output variant for regular AC loads up to 220V/8A.
- Order the input-reinforced 'XS' suffix for locations with frequent EFT events or heavy inductive-load switching.
- Add the optional 2.4GHz wireless version where wiring is difficult, or select a pulse-output ordering code if you need PWM speed control or PTO stepper/motor drive from the same module.
- Use RS-485 for long runs, multi-drop networking and noisy environments; use the built-in USB port for local configuration, as a USB-to-serial link, or as an RS-485 master once connected.
📘 Need the full method? NPN vs PNP Sensor Outputs Explained
When NOT to specify the D3J0304 — and what to use instead
Your machine has more than 4 sensors to read or drives more than 2 actuators from one board
Why not: D3J0304 is fixed at 4 fully isolated digital inputs and 2 digital outputs.
Use instead: Step up to D3J0308 (8-in/4-out) or D3J0312 (12-in/8-out) within the D3J03 family.
You are wiring a skid that only has sensors to report, or only actuators to switch, not both
Why not: Every D3J0304 unit carries 4 inputs and 2 outputs together on its 14 screw terminals; a pure-monitoring or pure-actuation panel leaves half the board unused.
Use instead: Use the pure-input D3J0104 or the pure-output D3J0202 module instead.
You want the input-linkage (output n follows input n) or the BRKFLG brake to serve as the certified interlock for a two-actuator machine's guard or e-stop circuit
Why not: Neither function carries a Type/SIL/PL rating and neither output is an OSSD - both are ordinary firmware features with a documented ~20ms typical response, not a certified safety loop. Both run locally on the module without the host, which is exactly why they get mistaken for a safety function, but they are not one.
Use instead: Add a DA31 Emergency-Stop Safety Relay Module or DQSRN Safety Relay Module for the actual safety function.
One of the 2 outputs must switch an inductive load pulling more than 8A, or an AC load above 0-220V
Why not: Relay output tops out at DC 30V or AC 0-220V/8A; transistor output (normal DC 12-48V or high-speed DC 12-24V) is also rated 8A, with a 10A absolute maximum even with its built-in flyback diode.
Use instead: Route the load through an external contactor sized for it, switched by the D3J0304 output.
You need the 2 outputs to react to combinations of the 4 inputs, timers or counters, rather than a fixed one-to-one linkage
Why not: Local logic on D3J0304 is limited to per-channel linkage, 5 delay/jog modes, and per-input edge counting (DINnCNT) and filtering (DINnFLT) - there is no programmable condition engine on board.
Use instead: Use the D4G0206 micro-PLC for real programmable logic across channels.
Your host system communicates over a fieldbus other than Modbus-RTU
Why not: D3J0304's default and only wired protocol is RS-485 Modbus-RTU at 9600bps/8-even-1, address 1-247, plus Modbus-ASCII/AT commands and an optional 2.4GHz Modbus-OTA link.
Use instead: Pick a module or gateway native to that fieldbus.
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.
- Mean time between failures (MTBF) for the module - not published
- Ingress protection (IP) rating of the enclosure - not stated in the source manual
- Full EMC compliance (radiated/conducted emissions, RF immunity) beyond the documented ESD/EFT/surge results - not published
- Resolution, accuracy and input voltage range of the 2 analog input channels - only described as voltage measurement, no numeric spec given
- PWM/PTO pulse output frequency range and step/pulse-count limits - no numeric value documented
- Wire gauge accepted by the 14 screw terminals - not stated
- Maximum number of RS-485 nodes per bus segment and maximum cable length - not stated
- Module weight (only L x W x H = 72 x 88 x 59mm is given) - not documented
Frequently Asked Questions
What is the D3J0304 used for?
Can the D3J0304 use relay or transistor outputs?
How does the local input-output linkage work without a host controller?
What are the jog and delay modes on the outputs?
Can I configure the module over USB instead of RS-485?
What are the extra analog inputs and pulse outputs for?
Does the D3J0304 meet industrial EMC and safety requirements?
Works Well Together
On the same machine or line, D3J0304 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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