DAM-4RO-4DI
RS-485 interface, 4 relay outputs, 4 digital inputs
Overview
- Industrial 4-channel relay module with 4 digital inputs.
- RS-485 interface and standard Modbus RTU protocol.
- Opto-isolated I/O; inputs support dry contact, NPN, and PNP wiring.
- Relays support flash on/off, timed switching, linkage, and other control modes.
- Dual isolation on the communication path with fuse, TVS, and surge protection.
- Stable and reliable for demanding industrial applications.
- High-voltage application. Follow electrical safety, leakage protection, and insulation requirements.
- Disconnect power before installation, maintenance, or relay replacement.
- Do not disassemble the module while energized—risk of damage or electric shock.
- Do not exceed rated load. For inductive or capacitive loads, leave adequate margin and add protection to avoid contact welding, overheating, or fire.
- Install in a dry, ventilated environment. Do not use in damp, overheated, or flammable locations.
Specifications
| Item | Details |
|---|---|
| Power | 6–36 V DC |
| Interface | RS-485 |
| Baud rates | 4800, 9600, 19200, 38400, 57600, 115200, 128000, 256000 |
| Default format | 115200, N, 8, 1 |
| Relays | 4 channels |
| Contact | SPDT (1 NO + 1 NC per channel) |
| Contact load | ≤10 A @ 250 V AC or ≤10 A @ 30 V DC |
| Digital inputs | 4 channels, 5–30 V; dry contact / NPN / PNP |
| Protocol | Standard Modbus RTU |
| LED | STA: slow blink idle; fast blink during communication |
| Dimensions | 145 × 90 × 40 mm |
Hardware interface
| Function | Pin | Description |
|---|---|---|
| Power DC 6–36 V | + | Positive |
| - | Negative | |
| Communication | RS485 A+ | RS-485 A |
| RS485 B- | RS-485 B | |
| G | RS-485 ground | |
| Relay | NC | Normally closed |
| COM | Common | |
| NO | Normally open | |
| Digital input | COM | Input common |
| DGND | Input signal ground | |
| X1–X4 | Channels 1–4 digital inputs |
RS-485 bus wiring
Most PCs have no RS-485 port. Use a USB-to-RS485 adapter; connect A to the module A terminal and B to B. For multiple devices, use twisted-pair shielded cable in a daisy-chain topology.
Relay output wiring
COM is the relay common; NC is normally closed; NO is normally open. By default COM–NC is closed and COM–NO is open (LED off). When energized, COM–NO closes and COM–NC opens (LED on).
Digital input wiring
X1–X4 are the 6 input channels; DGND is signal ground. COM is the input common—it may be left floating, tied to supply positive, or negative.
- Floating: dry contact (passive) input
- Tied to supply +: low-level trigger, NPN active input, 5–30 V DC
- Tied to supply −: high-level trigger, PNP active input, 5–30 V DC
 Dry contact wiring |  NPN active input wiring |  PNP active input wiring |
Operation demo
Two tools are shown below. Either works for first bring-up; the web serial assistant is recommended for a quick start.
- Web serial assistant: no install; full frame display and parsing; less intuitive for register data.
- Modbus Poll: direct register access; easier to read coil/input states; frames are not fully shown.
- Serial assistant
- Modbus Poll
Open the serial debug tool, select the COM port, set 115200 N 8 1, and open the port.
Enable hex display and hex send, set checksum to ModbusCRC16, send 01 05 00 00 FF 00. CH1 relay should turn on and echo the frame.
Use Module commands on the right to pick the module model and send preset commands, or expand entries to edit before sending.
Common commands builds Modbus function-code frames from parameters.
Install Modbus Poll and open it.
Setup → Read/Write Definition: set Slave ID, Function 01 Read Coils, Quantity to the actual channel count, then OK.
Connection → Connect Setup: Serial Port, select COM port, 115200 N 8 1, OK.
Double-click a coil value to toggle a relay (Send in the popup).
File → New, then Setup → Read/Write Definition: Function 02 Read Discrete Inputs, Quantity to the actual channel count, Scan Rate 100 ms.
Window 2 shows digital input states as inputs change.
Functions → 15: Write Multiple Coils: set start Address, Quantity to the actual channel count, set coil values, Send.
Display → Communication shows raw TX/RX data.
