.webp "Analogue to relay converter")
.webp "Relay output module")
.webp "Analogue to Relay module")
.webp "0-10 Volt to relay converter")
.webp "Analogue signal to relay output")
.webp "Analogue to digital converter")
Analogue signal to relay converter | High power | 230 VAC
Product description
The ARM-TH modules switch their relay output when the analogue signal exceeds a threshold value.
One analogue input to monitor one of the following analogue signals: 0-10 Volt / 0-20 mA / PWM.
When the threshold is exceeded, the solid state relay switches inductive loads between 20 VAC and 240 VAC with a maximum current of 2 A.
The unit can be connected to a Modbus RTU network to adjust settings or to overrule the relay output. It requires a supply voltage of 24 VDC.
The enclosure of the unit allows surface mounting and offers IP65 protection rating. The LED indicator shows the current status.
Additional specifications and description
What Does the Analogue to Relay Module Do?
This module converts an analogue input signal into a relay output signal based on a defined threshold. The module monitors one analogue input signal (0–10 Volt, 0–20 mA, or PWM). When the signal reaches a defined threshold, the relay switches. The threshold can be adjusted via Modbus (HR34), and the signal type can be selected via HR21. Configuration, remote control and firmware updates are done via Modbus RTU communication.
A typical application is ventilation control. If a CO₂ sensor sends a 0–10 Volt signal and the CO₂ level becomes too high, the module switches on a fan when the threshold value is exceeded.
How Does the Solid State Relay Work?
The ARM-TH uses a Solid State Relay (SSR) instead of a traditional electromechanical relay. The relay switches when the configured analogue threshold is exceeded. Because it works electronically and has no moving parts, it operates reliably, completely silent and without mechanical wear.
A mechanical relay uses physical contacts that move to open or close a circuit. Over time, these contacts can wear out due to mechanical stress and arcing. In contrast, a Solid State Relay switches electronically using semiconductor components. This makes it faster, more durable, and more resistant to vibration and frequent switching. Another important difference is lifetime and reliability. Since an SSR has no mechanical contacts, there is no physical wear. In addition, the control side and load side are electrically isolated, which protects sensitive control electronics.
SSRs are typically designed either for AC or for DC loads and are not interchangeable. ARM-TH is designed for AC loads. The SSR output can switch inductive loads in the range of 20 - 240 VAC. The maximum switching current is 2 A.
The integrated RGB LED lights up white when the relay output is OFF and green when the output is ON.
What Is the Intended Area of Use?
This module is designed for HVAC systems and industrial automation. It is commonly used in Domestic Controlled Ventilation (DCV) systems where values such as CO₂, temperature, humidity, or CO must trigger an action. Typical applications include fan control, alarm activation, and switching on/off heaters, dampers, dehumidifiers, pumps, or warning lights. The module acts as a simple interface between sensors with analogue output and switching devices.
What Are the Power and Wiring Requirements?
The module needs a 24 VDC supply voltage. Spring-loaded terminal blocks are used to connect the power supply, Modbus communication (RS485), and analogue input. The relay output is connected via a screw terminal block.
Can the Relay Be Controlled via Modbus RTU?
Yes. The relay can be controlled directly via Modbus RTU communication. This makes it possible to remotely overrule the relay output.
When the value 0 is written to holding register 31 (HR31), the Modbus master takes control of the relay. The relay can then be switched via HR32 (0 = OFF, 1 = ON). When HR31 is set back to 1, the relay is controlled again by the analogue input signal.
What Are the Protection Features and Mounting Requirements?
The enclosure is made of durable r-ABS VO (UL94) plastic and provides IP54 protection against dust and water. The device must be wall-mounted and should not be installed in direct sunlight. Thanks to its robust design, it is suitable for demanding environments.
Remarks, reviews & ratings