The MDM4881 from Micro Sensor is an intelligent differential pressure transmitting controller built around an ARM processing chip. It combines a precision differential pressure sensor, 4-digit 14-segment LED display, 5 independent relay control outputs, and a switchable 4–20 mA / 0–10 V analog output in a single IP65-rated field-mountable enclosure. Push-button programming — without a handheld communicator or PC — allows on-site configuration of switch points (1.5% to 99% FS), return difference (1% to 10% FS), and time delays (0 to 99 seconds), making it a self-contained alternative to separate transmitters, switches, and PLC I/O modules.

How do the 5 independent relays simplify pressure-based automation?

Each of the five relays can be individually configured as normally open or normally closed, with its own setpoint, hysteresis, and time-delay parameters. This allows a single MDM4881 to handle multi-level pump start/stop sequencing, high/low alarm annunciation, valve interlocking, and emergency shutdown — functions that would otherwise require multiple discrete pressure switches, timers, and relay logic. Relay response time is under 1 millisecond, and mechanical life exceeds 10 million cycles at minimum load or 100,000 cycles at maximum rated load (3 A / 277 V AC). A peak pressure recording function captures the maximum pressure reached during operation and can be cleared via the front-panel button.

What mounting and environmental options does the MDM4881 offer?

The MDM4881 supports four mounting configurations: back mounting, 35 mm DIN rail mounting, panel/cover mounting, and joint mounting, accommodating both new installations and retrofit projects. It operates from -25°C to +65°C with 0% to 85% relative humidity and withstands vibration up to 5 g (10 Hz–500 Hz, per IEC 60068-2-6) and shock up to 10 g (11 ms, per IEC 60068-2-27). The standard version accepts 220 V AC or 22–32 V DC power. An intrinsically safe variant (Ex ib IIA T6 Gb, certified to GB3836.1 and GB3836.4) is available for hazardous-area installations, powered via a safety barrier at 22–28 V DC. Modbus communication is supported for integration with SCADA and plant-wide monitoring systems.