What Is SCADA? Supervisory Control Without Replacing the PLC
SCADA sits above PLCs and RTUs: it acquires field data, alarms operators, and issues supervisory commands across plants and remote assets—without replacing local deterministic control.

Engineered for high-speed data processing and expansion within the MELSEC-Q control architecture, the Mitsubishi Electric Q4MCA-2MBS is a high-reliability Static RAM (SRAM) memory cassette. This hardware-level module expands the available volatile storage capacity of compatible high-performance Q-Series CPU modules, enabling handling of extensive file registers, recipe data, system logging, and trace functions. Because it utilizes high-speed SRAM technology, it provides near-instantaneous read and write execution cycles crucial for time-critical industrial processes.
| Manufacturer | Mitsubishi Electric |
| Model Number | Q4MCA-2MBS |
| Series Name | MELSEC-Q Series |
| Memory Type | SRAM (Static RAM) |
| Memory Capacity | 2 Mbytes |
| Dimensions (H x W x D) | 4.9 cm x 3.2 cm x 1.85 cm |
| Net Weight | 0.02 kg |
| Shipping Weight (Calculated) | 1.00 kg (protective packaging included) |
Because this expansion card uses volatile SRAM technology, memory retention is fully dependent on the host CPU battery system (such as the Q6BAT). If the system is powered down and the CPU battery level drops below the operational threshold, all register data and files hosted on the memory cassette will be permanently lost. It is critical to implement regular automated backups from the volatile cassette to a non-volatile flash ROM card or external SCADA/HMI server.
Before mounting or unmounting the cassette, verify the static potential of your work area. Always wear an ESD-grounded wrist strap when handling the card to prevent localized electrostatic discharge from damaging the exposed memory bus contacts on the rear connector interface.
Do not attempt to insert or extract the memory cassette while the PLC main power supply or expansion chassis power is energized. Failing to completely de-energize the unit will cause physical short-circuits on the CPU interface bus, destroying the CPU module, the memory cassette, or corrupting active running registers.
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| Country of origin |
United States
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