DT80 and SDI-12 Bus Operations
The DT80 logger supports SDI-12 applications and this means that information from any VibWire-108 instrument can be accessed and processed. The diagram below shows how many VibWire instruments can be connected together and on to which port they can communicate to the DT80. The VibWire-108 has 16 configurable inputs and all can be accessed by the logger unit.
The number of sensors shown deployed deployed is based upon the basic specification for each network. Keynes Controls can expand the SDI-12 network identifier to 36 nodes instead of the standard 10 and 255 nodes fo the 485 network upon request.
The DT80 logger supports SDI-
The number of sensors shown deployed deployed is based upon the basic specification for each network. Keynes Controls can expand the SDI-
From 1 to 32 VibWire Instruments on standard RS485 network
Digital Interface - DT80
The RS-485 network within the DT80
supports 32individual VibWire-108
instruments
256 Vibrating wire sensor inputs
256 Analogue inputs
supports 32individual VibWire-
instruments
256 Vibrating wire sensor inputs
256 Analogue inputs
8 Vibrating Sensor Inputs
&
8 Analogue / Current loop inputs
&
8 Analogue / Current loop inputs
Stand-alone DT80 Deployment - Up to 32 Sensor Inputs
For small stand-alone applications the recommended method of deployment is shown below. A single SDI-12 network connection wired to a daisy chained group of VibWire-108 units offers the simplest and most convenient way of forming multi-channel geotechnical applications.
To speed up scan times the VibWire-108 can be configured to operate with 2 to 8 sensors however the lower the sensor count the faster the instrument will respond. The sample time per VibWire-108 instrument is dependent on the number of vibrating wire sensors being used and the operating frequency of the sensors. The lower the operating frequency of the sensors the longer it will take to determine the measured frequency.
For fixed applications where no prior knowledge for the response of the sensors is known then a delay of 60 seconds after making the request to measurement until reading the sensor values back from the VibWire-108 is recommended. After this time all sensors will
The analogue input is limited to 0 - 2.5V DC
Each SDI-12 network supports to
80 Vibrating wire sensor inputs
80 Analogue inputs.
80 Vibrating wire sensor inputs
80 Analogue inputs.
