CST-MDP Differential Pressure Transmitter

Pressure measurement

The CST-MDP differential pressure transmitter measures differential or gauge pressure and converts it into a proportional analogue output signal. It is available with either a 0–10 VDC voltage output or a 4–20 mA current output, covering ranges from 0~±50 Pa up to 0~±10,000 Pa. Purpose-built to measure very low differential pressures, the CST-MDP is ideal for air flow monitoring and control applications, as well as for manometers and medical devices. Made in the UK.

Advantages

  • Accurate low-pressure measurement, from as low as 0~±50 Pa
  • Two selectable output signals: 0–5/10 VDC or 4–20 mA
  • Optional RS-485 output with Modbus RTU or BACnet MS/TP protocol
  • One-touch zero calibration button with LED confirmation
  • Adjustable output response time (0.5 s, 1 s, 2 s, or 4 s)
  • Compact, lightweight housing (140 g) in flame-retardant UL94-V0 plastic
  • High overpressure capacity (up to 15× rated range)
  • Wide operating temperature range, down to -40°C

Features

  • Accuracy: ±1.0% FS
  • Compensated temperature range: -10 ~ 60°C
  • Zero / full range temperature deviation: ±0.01% FS/°C
  • Overpressure capacity: ×15
  • Output signal: 0–5/10 VDC (3-wire) or 4–20 mA (2-wire)
  • Supply voltage: 10–30 VDC (0–5/10 VDC, 3-wire); 12–30 VDC (4–20 mA)
  • External load: ≥50 kΩ (0–5/10 VDC); ≤250 Ω (4–20 mA)
  • Response time: 0.5 s, 1 s, 2 s, or 4 s (selectable)
  • Operating temperature: -10 ~ 60°C standard; -40 ~ 85°C extended
  • Housing material: Industrial flame-retardant plastic, UL94-V0
  • Process connection: Metal barbed interface, Ø26.2 mm
  • Cable entry: Ø8 mm cable diameter
  • Weight: 140 g
  • Media compatibility: Air and neutral gases

Communication & Operation

The CST-MDP offers two analogue output modes — voltage output (0–5/10 VDC) or current output (4–20 mA). The voltage output uses a three-wire connection and must be wired according to the terminal label; the current output uses a two-wire, non-polarized connection, so wiring can be connected either way round.

An RS-485 communication option is also available, supporting either the Modbus RTU or BACnet MS/TP protocol. The Modbus protocol uses function codes 0x03 (Read Holding Registers) and 0x06 (Write Single Register); full register details are available in the separate Modbus and BACnet communication protocol documents.

A built-in zero button allows on-site calibration: with zero differential pressure applied across the positive and negative ports, pressing the button (LED confirms the action) resets the zero point. The output response time can also be configured on site.

Industry Applications

  • Process automation and control systems
  • Heating, Ventilation and Air Conditioning (HVAC)
  • Energy management systems
  • Static duct pressure monitoring
  • Clean room pressure monitoring
  • Indoor air pressure monitoring
  • Air filter monitoring
  • Over-pressurization and furnace draft control

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