Clas Ohlson ST-171, Manual

5

English

6. LED readings

N.B. 

The LED flash interval is factory-installed to 10 seconds but can be changed from 

10 seconds to 20 or 30 seconds with the accompanying software “Datalogger Graph” to save 
battery energy. LED flashing for an activated alarm can be shut off with the accompanying 
software to save battery energy.

LEDs

Indicates

Function

REC ALM

No LED showing.

Battery not installed or 
completely empty. Install or 
change battery.

REC ALM

1.  Green flashes every 10 seconds. 

(Measurement taking place and 
alarm is not activated).

2.  Green double flash every 10 seconds. 

(Manual start is activated in software but 
data logger has not started).

1.  Working normally.
2.  Press the yellow button on 

the data logger. The green 
and yellow LEDs flash 
once simultaneously and 
measurement then starts.

REC ALM

1.  Red flashes every ten seconds. 

(Measurement taking place and alarm for 
low RH has been activated). If alarm for 
both temperature and air humidity have 
been triggered, the LED flashes alternately 
every other time.

2.  Red double flash every ten seconds. (Alarm 

for high RH is activated). If the alarm for 
both temperature and humidity has been 
triggered, the LED flashes every other time.

3.  Red flashes every ten seconds 

(Bad Battery).

1.  Working normally.
2.  Working normally.
3.  Measuring stops automatically 

when battery is empty. Saved 
data remains even if battery is 
depleted. Replace battery and 
then connect data logger to 
a PC and transfer saved data. 
The Datalogger Graph program 
is needed to transfer data and 
to later start data logger to 
resume measurements.

REC ALM

1.  Yellow flash every ten seconds. (Measurement 

taking place and alarm for low temperature 
has been activated). If both temperature 
and humidity alarms have been activated, 
the LEDs flash alternately every other time.

2.  Yellow double flash every ten seconds (High 

temperature alarm has been activated). If both 
temperature and humidity alarms have been 
triggered, the LED flashes every other time.

3.  Yellow flash every 60 seconds (Data logger’s 

memory is full).

1.  Working normally.
2.  Working normally.
3.  Transferring data to PC.

REC

ALM