The Q68ADV is an 8-channel analog voltage input module from Mitsubishi Electric, belonging to the MELSEC-Q series of programmable logic controller I/O modules. It accepts voltage signals in configurable ranges and converts them to 16-bit digital values for processing by the MELSEC-Q CPU. Available now at Atlantech Drives with worldwide express delivery and 12-month warranty — complete our quote form for pricing and availability.
What Is the Mitsubishi Q68ADV?
The Q68ADV is a high-density analog voltage input module designed for integration into the MELSEC-Q base unit. With 8 independent input channels and 16-bit resolution, it is suited for applications requiring simultaneous acquisition of multiple analog process variables, such as pressure, temperature (via transmitter), flow rate, and position signals. Each channel is independently configurable for input range and averaging, making the module versatile across different field signal types on the same base.
Key Technical Specifications
- Number of channels: 8 (voltage input)
- Resolution: 16-bit (1/32000 of full scale)
- Input voltage ranges: 0–5 V DC, 0–10 V DC, –10 to +10 V DC, 1–5 V DC
- Input impedance: Approx. 1 MΩ
- Conversion speed: 80 µs/channel (normal mode), 160 µs/channel (high-accuracy mode)
- Overall accuracy: ±0.1% (at 25°C ambient)
- Isolation: Optical isolation between channels and bus
- Power consumption: 5 V DC, 0.35 A (internal bus)
- Compatible base units: MELSEC-Q main base, extension base units
- Applicable CPU: Q series CPU modules (Qn, QnH, QnPH, QnPRH)
- Number of occupied I/O points: 16 points
- Operating temperature: 0 to 55°C
Compatibility & System Integration
The Q68ADV is mounted directly into any slot of a MELSEC-Q main base unit (Q3□B, Q5□B, Q6□B, Q1□B series) or an extension base unit, subject to total power budget constraints of the base. It is compatible with all standard MELSEC-Q CPUs including the QnUDE(H), QnUD(E)HCPU, and motion CPU configurations. Configuration and channel scaling are performed via GX Works2 or GX Developer using the intelligent function module parameters dialog — no ladder rungs are required to set up scaling, averaging, or alarm output. The module writes converted digital values to buffer memory, which the CPU reads using the FROM/TO instructions or via auto-refresh assignment in GX Works2. For redundant system configurations using the QnPRHCPU, the Q68ADV operates identically on both the control and standby bases, with CPU switchover transparent to the analog acquisition process.
Installation Advice
When wiring the Q68ADV, use shielded twisted-pair cables for all analog signal lines and connect the cable shield to the module’s shield terminal (SHD) at one end only — grounding at both ends introduces ground loop currents that degrade measurement accuracy. Keep analog signal cables physically separated from power cables and digital I/O wiring by at least 100 mm, routing them in separate cable trays wherever possible. Set unused input channels to the «unused» state in GX Works2 parameters to prevent them from contributing noise to active channel conversions. Verify that the field signal source impedance is well below 1 MΩ to avoid input loading errors — for high-impedance sources such as certain pH electrodes, interpose a signal conditioner with a low-impedance buffered output.
Frequently Asked Questions
Q: Can the Q68ADV be used in a redundant MELSEC-Q system?
A: Yes. The Q68ADV is compatible with QnPRHCPU redundant configurations. Both the control and standby CPUs access the module normally, and CPU switchover is transparent to the analog acquisition cycle.
Q: What is the difference between Q68ADV and Q64AD?
A: The Q64AD provides 4 channels configurable for either voltage or current input, whereas the Q68ADV provides 8 channels dedicated to voltage input only. Choose the Q68ADV when higher channel density and voltage-only input is required; choose the Q64AD when current loop (4–20 mA) inputs are needed.
Q: Is high-accuracy mode available on all 8 channels simultaneously?
A: Yes, but enabling high-accuracy mode on all 8 channels increases the per-channel conversion time to 160 µs, resulting in a total scan time of 1.28 ms for all channels. For most process control applications this is well within acceptable limits.
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