This document is the user's guide for Vaisala DRYCAP® Dewpoint Transmitter DMT242. DMT242 is a dewpoint transmitter designed for a wide range of OEM applications. It offers excellent long term stability and features an automatic calibration procedure. The DMT242 utilizes Vaisala DRYCAP® polymer sensor technology, which is also resistant to condensation in case of system malfunction. The product is designed for harsh environments and provides protection against dust, dirt, and splashed water. The transmitter can be easily disconnected and reconnected using the connector for signal output and power supply wire connections. It also includes a serial line for rescaling the analog output.
This guide provides instructions for installing, wiring, and maintaining the Vaisala DMT242 dewpoint transmitter, a sensor designed for harsh industrial environments. It includes pressure‑setting procedures, mounting steps, wiring details, and calibration recommendations.
Key sections cover the technical specifications, serial communication settings for analog output scaling, accessory part numbers, and service centre contact information, helping users achieve accurate dew‑point measurements in a variety of processes.
| Measurement range | -80 to +60 °C (-112 to +140 °F) |
|---|---|
| Dewpoint accuracy | ±2 °C (±43.6 °F) |
| Analog output range | 4–20 mA |
| Analog output resolution | 0.002 mA |
| Operation voltage | 17–35 VDC, 20–28 VAC |
| Power consumption | max 220 mA at 24 VDC |
| Ingress protection | IP65 (NEMA 4) |
| Operating temperature | 0 to +60 °C (32 to +140 °F) |
| Pressure range | 0–20 bar (0–290 psi) |
| Probe material | Stainless steel (AISI 316L) |
Wait about 7 minutes after power‑on; the start‑up self‑diagnostics freeze the output during the first minutes.
The analog output signal spans 4 to 20 mA.
Send the command "asel xx yy
A calibration check is recommended every other year.