Mitsubishi MELSEC-Q Q68ADV Analog Input Module

The Mitsubishi MELSEC-Q Q68ADV Analog Input Module is an eight-channel, high-resolution analogue-to-digital converter module for the MELSEC-Q series modular PLC platform, providing 16-bit resolution measurement of voltage signals across five selectable input ranges: 0–5 V, 0–10 V, −10 to +10 V, 1–5 V, and 0–5 V (for 0.5 V reference offset applications). Each of the eight channels is independently configurable for input range, sampling mode, and digital filter, enabling a single Q68ADV to simultaneously serve as a precision process instrument input (for thermocouple transmitter 1–5 V signals), a setpoint reference input (0–10 V from operator station), and a feedback input (±10 V from position transducer) in the same application without channel-to-channel interference. The module's conversion time of 40 μs per channel in normal mode and 1 ms per all-channels in high-speed mode supports both slow process variable monitoring and fast closed-loop control applications within a single I/O scan framework.

The Q68ADV's 16-bit resolution provides 65,535 count conversion range with a guaranteed accuracy of ±0.1% of full scale at 25°C, degrading to only ±0.3% across the full operating temperature range of 0–55°C — performance that exceeds many competing analogue modules in the Saudi market that specify ±0.5% at temperature. The module's built-in channel diagnostics generate a wire-break detection alarm and over-range alarm on each channel independently, identifying signal faults in wiring between field instruments and the panel without requiring the PLC CPU to execute diagnostic ladder logic — a significant simplification for Saudi system integrators maintaining legacy MELSEC-Q installations. The scaling function (A-B conversion) embedded in the module firmware converts the raw A/D count to engineering units (kPa, °C, m³/h) directly at module level, reducing PLC CPU scan time and simplifying the application program.

In Saudi Arabia, the MELSEC-Q platform remains the most widely deployed Mitsubishi PLC architecture in the oil and gas, water treatment, and heavy process industries, having been specified extensively in the late 1990s through 2010s for Aramco upstream facilities, SABIC petrochemical units, and SWCC desalination plants across the Kingdom. Thousands of existing MELSEC-Q systems in active production service require analogue expansion modules for process variable monitoring and control loop closure. The Q68ADV is the primary voltage analogue input module for these installed-base systems, providing plant engineers with confidence that the module integrates seamlessly into existing Q-series racks, QnUDEH and QnUDE CPU configurations, and existing GX Works2 application programs without architecture changes. Saudi instrument engineers also specify the Q68ADV for new analogue input marshalling panels in MELSEC-Q upgrade projects, where 4–20 mA current signals are converted to voltage by field-mounted load resistors before entering the panel.

Razz Middle East maintains stock of Q68ADV modules and key MELSEC-Q accessories — power supply modules, base units, bus extender cables — in Riyadh for immediate delivery to Saudi system integrators and plant maintenance teams. Our technical team provides backwards-compatibility verification for Q68ADV integration into existing MELSEC-Q CPU and base unit configurations, channel scaling parameter setup assistance, and GX Works2 function block examples for analogue scaling and limit checking. Priority spare-parts supply for emergency plant breakdowns is available with four-hour quotation response. SAR pricing with import duty documentation is provided for all direct-purchase and project orders.