OMRON NT631C-ST151-EV2 HMI: 10.4-Inch Monochrome Touch Screen Programmable Terminal

The OMRON NT631C-ST151-EV2 is a rugged programmable human-machine interface (HMI) belonging to the NT631C series. Featuring a 10.4-inch monochrome LCD with STN (Super Twisted Nematic) technology, this touch screen terminal provides clear visibility and reliable operation in industrial environments. It is designed to interface directly with OMRON PLCs (CP, CJ, CS, CV series) via Host Link, NT Link (1:N), or RS-232C/RS-422A/485 communication, enabling real-time data display, alarm management, and parameter setting.

Display and Touch Panel Specifications

The NT631C-ST151-EV2 offers a monochrome (blue mode) LCD with a resolution of 640 x 480 pixels (VGA). The display area measures 211.2 x 158.4 mm, with an effective viewing angle of ±40° horizontally and ±30° vertically. The backlight is a CCFL (cold cathode fluorescent lamp) with a typical lifetime of 50,000 hours. The resistive analog touch panel has a resolution of 1024 x 1024, requiring an activation force of 0.5 to 1.0 N. It supports finger or stylus input with a durability of over 1 million touches per point.

Memory and Processing

The NT631C-ST151-EV2 is equipped with 4 MB of application memory (flash EPROM) for storing screen data, macro programs, and fonts. It supports up to 500 screens (each up to 64 KB) and includes 64 KB of recipe memory. The CPU is a 32-bit RISC processor running at 80 MHz, ensuring fast screen transitions and real-time data update rates of up to 50 ms for 100 variables. A real-time clock (RTC) with a lithium battery backup (5-year life) is standard.

Communication and PLC Connectivity

The HMI provides two serial ports: COM1 (RS-232C) and COM2 (RS-422A/485 selectable). Supported protocols include OMRON Host Link (SYSMAC WAY), NT Link (1:1 or 1:N up to 32 stations), Modbus RTU (master/slave), and general-purpose no-protocol communication. Using the NT link, the HMI can directly access PLC memory areas (CIO, DM, WR, HR) without ladder programming on the PLC side. The EV2 version adds enhanced communication stability and support for CJ2/CP1 series PLCs. An optional Ethernet unit (NT631C-ETN) is available for network connectivity.

Programming and Software

Screen design is done using OMRON’s NTST (NT-series Support Tool) version 4.8 or higher, running on Windows. The software allows creation of graphic elements (rectangles, circles, bitmaps), numerical displays, lamps, touch switches, trend graphs, and alarm lists. Macro functions enable complex calculations, conditional operations, and recipe data management. The HMI supports 8 levels of passwords to restrict access to screens or objects. Up to 128 alarms can be defined with history logging.

Environmental and Mechanical Specifications

The NT631C-ST151-EV2 is rated IP65 for the front panel (dust-tight and protected against water jets), while the rear is IP20. Operating temperature is 0°C to 50°C, storage -20°C to 60°C, humidity 35% to 85% non-condensing. It withstands vibration of 10 to 57 Hz (0.075 mm amplitude) and shock of 147 m/s² (15G). The unit measures 315mm (W) x 240mm (H) x 52mm (D) and weighs 2.7 kg. Mounting is via panel cutout of 296 x 223 mm with 4 screws. The HMI is powered by 24 VDC (20.4 to 27.6 V), consuming 20W typical.

Typical Applications

The NT631C-ST151-EV2 is used in machine tool control panels, packaging line operator stations, textile machinery, and small process skids. Its monochrome display offers high contrast even under ambient light, making it suitable for bright factory floors. The HMI can replace physical pushbuttons and indicators, reducing panel space and wiring complexity. With its robust construction and direct PLC connectivity, it remains a reliable choice for legacy system upgrades or new equipment where a color display is not required.

Accessories and Ordering Information

Standard accessories include mounting brackets, a power connector, and a communication cable (RS-232C, 3m). Optional accessories: protective sheet (NT631C-CVR3), backlight replacement kit (NT631C-BL01), and Ethernet unit. The model NT631C-ST151-EV2 replaces the older ST151-EV1 version, adding improved vibration resistance and updated firmware. OMRON provides a 3-year warranty. When ordering, specify the complete model to ensure compatibility with the target PLC. The HMI is fully RoHS compliant and CE marked.