Continuous dew point monitor with RS485


The TWA RS485 is a humidity sensor with remote sensor. It is mounted on cooling/cold water pipes or on cool surfaces. It can be used as a humidity sensor, dew point monitor or limit switch on pipes to prevent condensation on pipes. Installation is possible both on metal pipes and optionally with heat conductive paste on plastic pipes is possible.

The dew point temperature is the temperature at which the air reaches saturation and water begins to condense. Unit and line interruptions are signalled at the same time.

Technical Data

Power supply:24V DC ± 20%
Power consumption idle:5mA
Bus protocol:RS485 Modbus®-RTU
Configuration option:via Dip switches (address number, parity,
Address number:1 to 63 (0 not allowed)
Parity mode for Modbus:no parity, even parity, odd parity
Transmission rate:4800, 9600, 19200, 38400 Baud
Humidity sensor:MB: 0 ... 100%, error at 100%,
typically 3.5% MB: 20 ... 80%, error typical 2%
Sensor head:PP GF30 + aluminium, protection class IP50
Cable length:SStandard 200mm, option up to 1000mm
Process connection:Cable tie, 180 mm, for pipes up to 3" (included)
when mounting on plastic pipes,
a heat-conducting paste is necessary
Housing:Plastic, polyamide, 30%
glass-ball reinforced, with quick-release
screws, colour pure white (similar to RAL9010)
Dimensions:70 x 62 x 37mm
Cable gland:2 x M16, with strain relief
Ambient temperature:-30°C...+60°C
Humidity:< 95 % rH, non-condensing air
Electrical connection:up to 1.5mm² via double push-in terminals
Protection class:III (according to EN 60 730)
Protection type:IP63