Issue
When using SHD100 or SHD101 humidity sensors with a BAS 2800+ Outstation or Sigma Controller, the sensors may output a DC voltage exceeding the expected 0–10V range. This can cause the controller to display a default or erroneous value.
Product Line
Satchwell BAS & SigmaEnvironment
- BAS 2800+ Outstation
- Sigma Controller
- SHD100 / SHD101 Humidity Sensors
Cause
The sensors are capable of producing a DC voltage signal greater than 10V. When this occurs, the controller may interpret the signal as out-of-range and revert to a default value, potentially triggering alarms or incorrect readings.
Resolution
To prevent out-of-range errors and ensure accurate readings:
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Add a Series Resistor
Install a 10K ohm, 0.1% tolerance resistor in series with the 0–10V signal line. This helps limit the voltage and protect the input circuitry.
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Create a Lookup Table
In Sigma or BAS 2800+, configure a lookup table with the following values:
Input (mV) Output (%) 0 0 83335 100 100000 100 This table allows the system to interpret voltages up to 11.335V without triggering an out-of-range alarm.
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Apply the Table
Assign the lookup table to the analog input object. Then download both the object and the table to the Outstation or Controller.
Outcome
With this configuration, the system will tolerate sensor outputs up to 11.335V, ensuring stable operation and avoiding false alarms.
