The Orbit Merret OMC 8000 is a modular digital input PLC that distinguishes itself through the exceptional versatility of its onboard inputs. The heart of the system is a compact main module measuring just 72 x 90 mm, which houses three dedicated digital inputs and—more notably—six universal analog inputs. These universal channels are the defining feature of the OMC 8000: a single input terminal can be configured to accept pulse signals up to 30 V, standard analog voltage (0-30 V) or current (0-20 mA), resistance measurements up to 3900 Ω, or a comprehensive array of temperature sensors including Pt100/Pt1000 RTDs and thermocouples of types B, E, J, K, L, N, R, S, T, and XK. This flexibility means a single controller can interface with a diverse mix of field devices without requiring multiple specialized signal conditioners.

The OMC 8000's modular architecture is built around a robust CAN bus backbone. Up to 31 expansion modules can be connected to the main module, distributed locally or remotely with a maximum span of 40 meters between the furthest modules. This allows the system to scale precisely with application demands—from a standalone controller handling a few dozen I/O points to a distributed system managing hundreds. Expansion modules cover a wide spectrum of functions, including additional digital and analog I/O, combined modules with integrated power supplies, and specialized communication gateways. The system includes an Ethernet 100Base port and supports Modbus RTU and Modbus TCP/IP protocols, enabling straightforward integration into supervisory SCADA networks and higher-level control systems.

Beyond conventional I/O, the OMC 8000 incorporates several advanced capabilities. Two of the universal inputs can be configured as full quadrature encoder interfaces, capable of tracking incremental encoder signals at frequencies up to 1 MHz—a valuable feature for motion and position monitoring applications. The main module provides five outputs, available in either relay (10 A/250 VAC) or open-collector transistor (300 mA/30 VDC) configurations, with the transistor outputs supporting PWM at 10 kHz. A Micro SD card slot enables onboard data logging with user-selectable time stamps, allowing the PLC to record I/O states, alarms, and process trends for later analysis without a constant PC connection. A built-in web server provides browser-based access to system status and diagnostic information.

Programming the OMC 8000 is accomplished using MULTIPROG PRO®, a sophisticated development environment fully compliant with the IEC 61131-3 standard. This provides support for all five standard programming languages—Ladder Diagram, Function Block Diagram, Structured Text, Instruction List, and Sequential Function Chart—as well as advanced debugging tools including online editing, breakpoints, and a logic analyzer. The main module can be powered from a wide range of supply voltages, accepting either 230 V AC/DC or 24 V AC/DC, with a maximum power consumption of 5.5 VA. The controller is rated for operation from -20°C to +60°C, making it suitable for a broad range of industrial and building automation environments.

Technical Specifications