FAQ#083 – How does the TRIGGER function of OMNIAlog digital input work?

The TRIGGER function of the two digital inputs available on OMNIAlog datalogger is typically used with seismic station. In case of an event (earthquake), the seismic station is usually able to supply a certain tension on its output (typically 5Vdc). If this output is connected to the digital input of OMNIAlog, and OMNIAlog is conveniently […]

FAQ#081 – Which is the maximum cable length for DEX and DEX-S probes?

The maximum instrument cable length from DEX probe to datalogger is 200 m. If the automatic data acquisition system includes distributed external multiplexer box, the maximum cable length is 200m from DEX probe to multiplexer box plus 200m from multiplexer box to OMNIAlog (in total 400m).

FAQ#078 – Is it possible to send SMS in case of alarms with OMNIAlog?

Yes, if OMNIAlog is equipped with a 2G (GSM/GPRS) modem, connected through a serial cable to its RS232 port. OMNIAlog allows to set up alarm thresholds and the notification of these alarms could occur: – by SMS; – by email; – by FTP; – increasing the acquisition frequency; – managing a digital output (for example to manage […]

FAQ#077 – Which are the maximum cable lengths from instrument to datalogger?

The cable lengths depend from many factors, first of all installation and cable protections (screen, earth, etc…). Assuming that instruments are installed in a workmanlike, for the maximum cable lengths should be followed the next suggestions: DIGITAL INSTRUMENTS: see FAQ#73 ANALOGUE INSTRUMENTS: see both downloadable documents.

FAQ#076 – Why it is necessary add a termination resistor to the last digitized sensor of each RS-485 chain?

All SISGEO digitized instruments  (IPIs, Tiltmeters, H-Level…) use the RS-485 serial communication protocol The RS485 protocol contemplate a termination resistor. The recommended chain connection is point-to-point (multidropped) nodes as a bus mode (line). Star, ring or multiply network connection are not recommended. SISGEO dataloggers has already a termination resistor assembled (typically 120Ω). On the opposite […]

FAQ#074 – Which kind of datalogger is necessary to read a SISGEO digital sensors?

The sensors are read connecting the end cable to a Modbus Master unit (i.e. OMNIAlog or miniOMNIAlog) with RS-485 interface (DCE, Half duplex, no Echo) able to manage communication with SISGEO Modbus RTU communication protocol. SISGEO’s communication protocol is available for the release upon request. The power [W] of power supply must be chosen according […]

FAQ#073 – Which is the maximum number of digitized sensors (RS-485, Modbus), the maximum number of chains and the maximum length of cable in a RS-485 network?

Last update: October 2021 All the SISGEO digitized sensors utilize a RS485 interface with Modbus protocol. 1.The maximum number of digitized sensors in a RS-485 network are 247 (theoretical) 2.The maximum number of digitized sensors chains that is possible to connect to Modbus master unit (as OMNIAlog or miniOMNIAlog) are 4. 3. About the maximum […]