---
lang: "en"
title: "TDO340 MODBUS RTU relay output module"
sku: "TDO340"
canonical_url: "https://shop.marcomweb.it/en/remote-io/tdo340-modbus-rtu-relay-output-module"
brand: "TERACOM"
image: "https://shop.marcomweb.it/storage/5359/conversions/TDO340_1-webp.webp"
end_of_life: "false"
---

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TDO340: 4-channel relay output module with SPST relay contacts

The MODBUS RTU relay output module, TDO340, is a reliable 4-channel SPST device with independent contacts. It supports the MODBUS RTU protocol and allows setting the safety states of the relays on startup and in case of communication loss, ensuring system safety. The module includes a watchdog function that monitors communication failures and responds quickly to maintain safety. The TDO340 uses non-volatile memory to store the relay states and restore them after a power outage. It operates as an ideal relay output extension for MODBUS RTU master devices, with an RS-485 interface supporting up to 63 nodes. Additional features include an LED indicator for communication status and a wide power supply voltage range starting from 5VDC. The module also offers reinforced isolation for the relay contacts, adding an extra layer of system safety. A built-in 120-ohm termination resistor and simple DIN rail mounting make installation immediate. Firmware updates can be performed via the interface, simplifying maintenance.

## Technical Specifications

- RS-485 interface supporting up to 63 nodes
- Non-volatile memory to maintain relay state
- LED indicator for communication status
- Wide power supply voltage range, starting from 5VDC
- Watchdog functionality in case of communication loss
- Reinforced isolation for relay contacts
- Non-volatile memory for settings storage
- Built-in 120-ohm termination resistor
- Easy DIN rail mounting
- Firmware update via interface
- Operating voltage range (including -15/+20% according to IEC 62368-1): from 5 to 28VDC
- Current consumption: 130mA@5V
- Interface

- Protocol: Modbus RTU
- Physical layer: RS-485 serial line
- Operating temperature range: from -20 to 60°C
- Operating relative humidity range: from 10 to 90% (non-condensing)
- Storage temperature range: from -25 to 65°C
- Storage relative humidity range: from 5 to 95% (non-condensing)
- Protection rating: IP40 (connections IP20)
- Mounting: On 35 mm hats DIN rail

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Source: https://shop.marcomweb.it/en/remote-io/tdo340-modbus-rtu-relay-output-module

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