Operating Manual
ARS31(Pro)-UMB
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany
5
If there is no freezing temperature / salt concentration detected in a measuring cycle the
last identified freezing temperature will be delivered for the following 40 minutes (default:
40
– interval can be adjusted). During this interval the freezing temperature can only move
to 0°C if the sensor definitely detects clear water on the road.
The freezing temperature profile is smoothed by the sensor. This function can be disabled
using the UMB-Config Tool.
Data polling takes place through any desired host computer which supports any of the
communication protocols described in Section 6 and disposes of an RS485 interface.
Measurements are polled and transmitted over an RS485 interface.
The device is connected using a 4-core cable.
Windows PC software is available for configuration and measurement polling during
commissioning.
3.2 Additional features of ARS31Pro-UMB
In addition, ARS31Pro-UMB determines the threat of icing as follows: for a dry road
– by
cooling to an adjustable temperature value (∆ T1); for a wet road - by comparing the
measured freezing temperature with the road surface temperature while taking account of
the set temperature va
lue (∆ T2).If a threat of icing is determined using one of the methods
described above, the sensor transmits “threat of icing”.“Threat of icing” is only transmitted
as a result of a direct measurement if the road temperature ∆T is less than +1°C.
To avoid measurement gaps due to interference during measurement, the sensor is
equipped with an intelligent “hold measurement” function also for threat of icing.
If the condition “threat of icing” was triggered by the freezing temperature measurement
and the fre
ezing temperature enters the hold state, the condition “threat of icing” is also
updated via the last determined freezing temperature and the current road temperature. In
this case, updating of the threat of icing ends simultaneously with the updating of freezing
temperature. However, if during updating the threat of icing is actively determined by
means of a direct measurement, this condition is retained for the set period.
With external sensor the road surface temperature is determined exactly.
3.3 Availability of measurement values
After a successful measurement, the measurement values are available for query until new
measurement values are available. Synchronization between query and measurement
cycle is not needed. It is recommended to poll the sensor every minute. Within the
measurement interval the measured values are immediately updated when they become
available. Due to different environmental conditions the timing of the availability of
measurements can alter in the measurement interval, the measurement values are
therefore not necessarily updated in the grid of the selected measurement interval.
