# General information

<table border="1" id="bkmrk-download-technical-s" style="border-collapse: collapse; width: 100%;"><colgroup><col style="width: 50%;"></col><col style="width: 50%;"></col></colgroup><tbody><tr><td>Download technical specification</td><td>[Technical Specification](https://www.atreyo.in/sites/default/files/a-download/AMB-8I-4O%20Technical%20Specification.pdf)</td></tr></tbody></table>

The AMB-8I-4O input/output expander with Modbus RTU and IEC-60870-5-101 protocol support. (under development). It has 8 isolated digital inputs with voltage range up to 30VDC and 4 relay output with 5A 230V range and NO contacts. The power supply range is 8 to 48V DC. The use of DC / DC technology for supplying relays enables a wide range of supply voltages.

---

#### Connection information  


Below is a description of the expander connectors. The outputs of the expander are directly connected to the relay leads. The relays are of normal open type.

![AMB-8I-4O connectors.png](https://docs.atreyo.in/uploads/images/gallery/2025-03/u1pamb-8i-4o-connectors.png)

---

#### Wiring

The expander has opto-isolated inputs that require an external Voltage source in range of a 5-30V. The inputs can be driven by both positive and negative signals. Both examples are shown in the attached diagram.

The outputs of the expander are directly connected to the relay leads. The relays are of normal open type.

![AMB-8I-4O wiring.png](https://docs.atreyo.in/uploads/images/gallery/2025-03/scaled-1680-/amb-8i-4o-wiring.png)