Measuring the dewing of a higher number of cooling ceilings, etc.

A solution for a high number of measuring points with the peripheral Foxtrot module IT-1604.

If it is necessary to monitor the dewing of ceilings in several rooms, the IT-1604 module can be used (with some added external resistors), to which up to 8 SHS sensors can be connected.

The connection of the sensors including the required 39k and 270k resistors is illustrated in the following figure. For the range of the sensor resistance from 20 to 100 kΩ(which corresponds to about 70 to 93 % humidity), the output voltage measured by the module (1 V range used) should be approx. from 0.47 V (for humidity up to 75 %) to 0.94 V (for humidity up to 93 %).

Fig. .1 Connecting several SHS sensors to the IT-1604 module.
Notes:

1. The 39k and 270k resistors may have a 5 % tolerance, with no additional requirements.

2. The supply cable can be extended up to approx. 30 m. You should use a shielded cable, e.g. the SYKFY 2x2x0.5, or J-Y(St)Y 1x2x0.6.

3. When the sensor is being mounted, care should be taken to maintain quality conductive connection with the monitored surface, and to avoid damaging the active surface of the sensor.

4. Analogically as per the example, as many as 8 sensors can be connected to the AI1 to AI8 inputs.