User's Manual

LX-80 User Manual
Page 17 of 32
6. Data Protocols
Geolux LX-80 level meter supports the following data protocols:
• NMEA-like protocol on RS-232 interface that constantly outputs the
detected current level and averaged level based on the last 24
(parameterable) readings
• Servicing protocol on RS-232 interface for configuring the unit
• Request-response protocol (Modbus) on RS-485 interface that allows
multiple units to be used on a single RS-485 bus
Support for additional protocols is available upon customer request.
6.1. NMEA protocol (RS-232)
NMEA protocol is based on the standard protocol family widely used by the
navigation equipment. NMEA protocol is sentence oriented and can send multiple
sentences with different information. The sentence content is designated by the starting
keyword which is different for each sentence type. NMEA sentences are terminated with
the checksum which makes this protocol extremely reliable. NMEA protocol is
unidirectional; data is only transmitted from the level meter.
At RS-232 interface the device periodically outputs following data sentences:
Level measurement report
$LVX,L1,L2,T1,L3,L4,S<CR><LF>
$ LVX: The keyword sent on the beginning of each detection report. This sentence is
sent whenever there is detected level.
L1 : Current distance from sensor to water (in selected unit, default mm)
L2 : Average distance from sensor to water (in selected unit, default mm)
T1 : Electronic temperature (in °C)
L3 : Current relative detected level (in selected unit, default mm)
L4 : Average relative detected level (in selected unit, default mm)
S : Measurement SNR (in dBm)