Gemo AR2-A-24VDC-12D2A-TR-RTC – Expandable Smart Relay / PLC with Analog Inputs, Transistor Outputs and RTC

Gemo AR2-A-24VDC-12D2A-TR-RTC is a compact, expandable smart relay / PLC designed for machine automation, panel control and applications that require both digital logic and analog signal monitoring. It operates from a 24 VDC supply and combines 12 digital inputs, 2 analog inputs, 10 PNP transistor outputs, a dedicated PTC temperature input and a battery-backed real-time clock.

Gemo AR2 controllers have been available through our website since 2011.

Power supply and I/O

Power supply: Nominal 24 VDC, with an operating range of approximately 18–32 VDC. Maximum power consumption is 6 W.

Digital inputs: 12 inputs for 24 VDC control signals. Standard digital input filtering is at least 8 ms for both ON-to-OFF and OFF-to-ON transitions.

Analog inputs: 2 0–10 VDC analog inputs with 10-bit A/D resolution. These inputs can be used for monitoring compatible pressure, level, position, temperature-transmitter or other process signals.

A 4–20 mA transmitter should not be connected as though the controller provides a dedicated current input. The current signal must first be converted to a voltage within the permitted 0–10 V input range using a suitable resistor or signal converter.

Analog output: Not available.

Transistor outputs: 10 PNP transistor outputs, rated up to 32 VDC / 0.3 A. The 250 VAC / 2 A rating used for relay-output AR2 versions does not apply to this model.

PTC temperature input: One dedicated input is provided for a 2-wire PTC temperature sensor, with a measuring range of approximately -50 to +150 °C. The PTC channel is separate from the two 0–10 V analog inputs.

Battery-backed real-time clock

The RTC version includes a battery-backed real-time clock, allowing machine functions to be controlled according to actual date and time. Weekly and annual schedules can be created for pumps, ventilation equipment, lighting, process equipment and other applications that must operate at predefined times.

For applications that do not require calendar-based control, see the Gemo AR2-A-24VDC-12D2A-TR version without RTC.

Ladder programming and internal functions

The AR2 series is programmed with GEMO Ladder Editor. The ladder workspace supports 256 program lines, 5 contact columns and 1 output column, with rising-edge and falling-edge functions available for contacts.

Programs are transferred through the controller's RS-232 programming interface.

Available logic resources include 32 timers, 32 16-bit up/down counters, 32 offset counter comparators and 16 hysteresis analog comparators.

The analog comparator functions allow the two analog inputs to be used for threshold-based control, alarms and simple process decisions without requiring a separate analog controller.

Ladder scan time: Up to 10 ms.

Timer resolution: Minimum timing resolution is approximately 10 ms. Timer accuracy is specified as ±0.1% or 1 digit, whichever is greater.

High-speed counter inputs: Minimum ON and OFF times are approximately 1.25 ms. These inputs are intended for faster pulse counting and should not be confused with motion-control pulse outputs.

Servo and step motor control

Although this version uses transistor outputs, it does not provide a dedicated high-speed pulse / direction output for positioning servo or step motor systems. Applications requiring high-speed pulse-train positioning should use a PLC or motion controller designed specifically for motion control.

PID control

The presence of analog inputs does not mean that this controller includes a built-in PID loop. A dedicated PID algorithm is not provided.

Closed-loop temperature, pressure, flow or similar process-control applications should therefore use a suitable process controller or a PLC with integrated PID functionality.

Display and operator functions

The controller features a 2 × 16 character backlit LCD display, three programmable front-panel function keys and a three-level password-protected menu system. User screens can be configured to display analog measurements, machine status, operating values and application messages.

Can an external HMI be connected? Yes. A compatible operator panel / HMI can be integrated using the appropriate communication hardware.

For Modbus RTU communication, the appropriate AR2-S-24VDC-MB1 communication gateway and compatible controller software are required. The RS-485 expansion interface should not automatically be treated as a standard direct Modbus HMI port.

I/O expansion and RS-485

Compatible AR2 expansion modules can be connected through the controller's RS-485 expansion interface. The final number and type of available inputs and outputs depend on the selected expansion module and the base controller configuration.

RS-485 cabling: Use twisted, shielded, 2-core 24 AWG communication cable. Polarity, shielding and line termination should follow the manufacturer's wiring instructions.

Operating environment

Operating temperature: 0 to 50 °C.

Protection rating: IP20 according to EN 60529.

Relative humidity: Up to 80% at 30 °C, decreasing linearly to approximately 50% at 50 °C, non-condensing.

Terminal tightening torque: Maximum 0.5 N·m.

EMC and panel layout: EN 61000-6-1 and EN 61000-6-3 requirements should be considered during panel design. When the controller is installed alongside AC motor drives, frequency inverters, contactors or other sources of electrical noise, control and power wiring should be physically separated where practical.

Analog signal cables deserve particular attention: correct shielding, grounding and separation from motor and inverter wiring will help maintain stable measurements.

Gemo AR2 programming software and documentation

Download GEMO Ladder Editor V2.4 programming software for AR2 programming and configuration.

For detailed programming instructions, analog-input functions, timers, counters and RTC configuration, refer to the Gemo AR2 PLC English user manual.

For additional models and pricing, visit the Gemo price list, Gemo Electronic main page or our PLC product group.

For technical information and product selection, use our Gemo contact page or contact us at gemo@otomasyonavm.com.

Installation notice: Installation, wiring and commissioning of the Gemo AR2 should be carried out only by qualified technical personnel. Disconnect all power sources before working on the control panel. Particular care should be taken with analog, communication and power wiring to ensure reliable operation and compliance with the manufacturer's installation requirements.