Technical Overview
The Schneider PCBALU821 functions as a compact central processing unit for the Modicon M221 series programmable logic controllers. This module integrates a 32-bit microcontroller that supports up to 256 discrete I/O points for small to medium-scale automation tasks. Its embedded memory provides 256 KB for user programs and 128 KB for persistent data storage, respectively. Consequently, the PCBALU821 delivers reliable control for packaging machinery, conveyor systems, and simple material handling applications.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Schneider Electric |
| Product Type | PLC CPU Module |
| Processor | 32-bit microcontroller |
| Program Memory | 256 KB Flash |
| Data Memory | 128 KB RAM (retentive) |
| Maximum I/O Points | 256 discrete / 64 analog |
| Embedded Communication | 2 × Serial (Modbus RS-485) |
| Power Supply | 24 VDC (external) |
| Current Draw | 250 mA |
| Battery Backup | Internal lithium battery (5 years) |
| Real-Time Clock | Yes (battery-backed) |
| Processing Speed | 0.8 ms per 1K logic instructions |
| Dimensions (H x W x D) | 90 x 70 x 65 mm |
| Weight | 0.35 kg |
| Operating Temperature | -10°C to +55°C |
| Storage Temperature | -40°C to +85°C |
| Protection Class | IP20 |
| Certifications | CE, CSA, UL |
Memory Architecture and Data Retention
The Schneider PCBALU821 stores user programs in non-volatile flash memory, ensuring data integrity even during prolonged power outages. Its internal lithium battery maintains the real-time clock and retains retentive variables for up to five years. This design guarantees that critical process parameters persist through shutdowns without user intervention, thus minimizing downtime after power restoration.
Communication and Network Connectivity
Dual serial ports support Modbus RS-485 protocols, enabling seamless connectivity with HMIs, drives, and other Modicon devices. These communication channels allow integrators to build cost-effective control networks without additional communication modules. Furthermore, the CPU supports simple programming via EcoStruxure Machine Expert – Basic software, streamlining the development of machine control applications.
Integration and Application Versatility
The PCBALU821 fits directly into the M221 backplane, supporting both standalone and distributed architectures. Its compact dimensions enable installation in space-constrained control cabinets, while its 256 I/O capacity suits a wide variety of OEM machinery applications. With robust build quality and protection against temperature extremes, this CPU module ensures long-term reliability in demanding factory floor conditions.
Details
| Weight | 0.35 kg |
|---|---|
| Dimensions | 90 × 70 × 65 mm |
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