LANDIS PCD4.M110 Processor Module: Central Unit for Building Automation Systems

The LANDIS PCD4.M110 (also referenced as PGU PCD4M110 or PCD4.M110) is a high-performance processor module designed for the LANDIS PCD4 series of programmable controllers, widely used in building automation and HVAC systems. This module serves as the central processing unit, executing user programs, managing I/O, and handling communication with field devices. It complies with IEC 61131-3 standards, offering flexible programming and robust operation for applications such as energy management, lighting control, and heating/ventilation/air conditioning.

Processor and Memory Specifications

The PCD4.M110 is equipped with a 32-bit microcontroller running at 48 MHz, capable of executing 0.2 µs per basic instruction. It provides 256 KB of program memory (flash) and 128 KB of data memory (RAM). An integrated real-time clock with supercapacitor backup (minimum 14 days) supports time-based functions. The module supports up to 2048 digital I/O and 512 analog I/O when expanded with PCD4 series I/O modules. A lithium battery (CR2032) retains data memory for up to 5 years during power loss.

Communication Interfaces

The processor module includes an RS-232C port (for programming and modem connection) and an RS-485 port (for LANDIS GYR bus or Modbus RTU). It also features a built-in Ethernet port (10/100Base-T) supporting TCP/IP, Modbus TCP, and BACnet/IP protocols, making it suitable for integration into building management systems (BMS). Additionally, the PCD4.M110 has a P-bus (peripheral bus) connector for I/O expansion modules and a separate service port for firmware updates.

Programming and Software Environment

Programming is performed using LANDIS’s PGU software platform (e.g., PCD Tools or L-Home), which supports the five IEC 61131-3 languages: Instruction List (IL), Structured Text (ST), Ladder Diagram (LD), Function Block Diagram (FBD), and Sequential Function Chart (SFC). The software includes a built-in simulator, online monitoring, and debugging features. The PCD4.M110 supports up to 256 function blocks and 1000 variables. It also supports remote programming via Ethernet, allowing engineers to update control logic without physical access.

Operating System and Real-Time Performance

The module runs a multitasking real-time operating system (RTOS) with up to 8 cyclic tasks (1 ms to 10 sec intervals) and 4 event-driven tasks. It provides deterministic response times for critical control loops. The processor includes hardware watchdog timers for fail-safe operation. Built-in self-diagnostics include memory checks, CPU temperature monitoring, and communication error detection. Alarms can be reported via the system register or email notification (using the Ethernet port).

Physical and Environmental Data

The PCD4.M110 is designed for DIN rail mounting (35mm) in an enclosure. Dimensions: 100mm (H) x 60mm (W) x 90mm (D). It requires 24 VDC power (20-28V), consuming 150 mA typical (excluding I/O). Operating temperature range is -20°C to +60°C, storage -30°C to +80°C. Humidity 5% to 95% non-condensing. The unit is rated IP20 and complies with CE, UL 916, and RoHS. It also meets EN 61000-6-2 (immunity) and EN 61000-6-4 (emission) for industrial environments.

Typical Applications in Building Automation

The PCD4.M110 is commonly deployed in central plant controllers (chillers, boilers), air handling units (AHU), fan coil units, lighting control panels, and room automation systems. Its support for BACnet/IP enables native integration with third-party BMS. The processor can log energy consumption data (via Modbus meters) and generate trend reports. For legacy systems, the RS-485 port can interface with LON or M-bus devices via gateway modules. The module’s compact size and low power consumption make it ideal for retrofitting existing control panels.

Installation and Maintenance

Installation involves clipping the module onto a DIN rail, connecting power, and plugging I/O modules to the right side using the P-bus connector. The battery is replaceable without removing the module. Firmware updates are performed via the Ethernet port using the PGU tool. LANDIS provides a 2-year warranty and offers technical documentation (including the PCD4 Hardware Manual). When ordering, the correct model is PCD4.M110 (also known as PGU PCD4M110). The “SKIRT” designation may refer to a mechanical shield accessory, but the core processor remains the same.