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Pliant: readily yielding to influence

PSE
Pliant Shaft Encoder (Water Level Sensor)

Data Sheet (pdf)

PSE Shaft Encoder

Shaft encoder water level sensors use a float and counterweight mounted to either end of a punched stainless steel tape. This tape engages a pulley which is mounted on the shaft of the sensor. These sensors are characterized by greater resolution than typical pressure transducers used for the same purpose.

PSE optical shaft encoders are intelligent sensors providing data through a communications port (SDI-12, MODBus RTU, ...) in engineering units using user-programmable OFFSET and SCALE (units per revolution) settings. Hardware includes a +10.5 to14V input for external battery, charger or solar panel and a 9 V alkaline battery to provide a total of approximately 240 hours of backup in the event of power supply interruption. The shaft is mounted on precision, zero-resistance bearings and is compatible to our pulleys.

Inquire about our pulleys and punched tapes which are Leupold & Stevens compatible!

Some PSE shaft encoders include a relay output which is controlled by user-programmable high and low levels. This output provides an ALARM or ALERT control for conditions which typically correspond to drought and flood. The hysteresis for each of the trigger points is also user-programmable.

SDI-12 Interface: the "PSE-SDI"

The PSE-SDI provides a standard SDI-12 interface, version 1.3. SDI-12 commands allow the user to initiate a single sample of the water level or to calculate the average value based on a user-specified sampling period and number of samples. The SDI-12 host is generally a data logger such as the PDAS-III but an interface between your PC and the shaft encoder is possible by ordering the PCOM-SDI.

MODBUS RTU Interface: the "PSE/RTU"

The PSE/RTU provides MODBUS registers that include the water level to 3 decimal places, OFFSET, Units per revolution (SCALE), Alarm trigger points. Distances of up to 4000' are supported between the PSE/RTU and the host using two twisted pairs (full duplex).

Ask about the PSE/RTU relay output which provides ALERT hardware control for user-specified alarm levels corresponding to flood and drought conditions.

Modem-based Communications

The PSE shaft encoder can be equipped with a leased-line or dial-up modem. This allows practically unlimited distances between the sensor and the polling device.

The PSE/RTU/MDMLL provides a built-in leased-line modem. This must be purchased in conjunction with a Remote Terminal Unit (RTU) with Display and built-in leased-line modem (the PRTU/RTU/MDMLL, contact us). The PRTU/RTU/MDMLL polls the remote sensor at a fixed frequency of once per second. It then displays the real-time readings on an LED digital display and makes the data available to a MODBus host such as a SCADA or PLC, or an analog device using a 4-20mA loop (Option "/4-20").

The PSE/RTU/MDM provides a built-in dial-up modem. This must be purchased in conjunction with a Remote Terminal Unit (RTU) with Display and built-in dial-up modem (PRTU/RTU/MDM, contact us). The PRTU/RTU/MDM calls and polls the remote sensor at a fixed frequency. It then displays the real-time readings on an LED digital display and makes the data available to a MODBus host such as a SCADA or PLC, or an analog device using a 4-20mA loop (Option "/4-20").

"/4-20" Option: 4-20mA Output

The "/4-20" option provides a 4-20mA current loop output which is proportional to the current water level. The analog output makes use of a 16-bit DAC.
The water levels corresponding to an output of 4mA and 20mA are user-configurable from the digital display. Also, although the DAC is factory-calibrated, the unit features a calibration mode whereby 4mA and 20mA current levels are provided as a reference for fine adjustment of the device if necessary.


Note that the "/4-20" option must be purchased with the
Digital Display option described below.

"/D" Option: Digital Display Interface

The PSE shaft encoders are available with a LED display and interface that allows the user to view the current level as well as set up the unit without the use of a host device. The following set-up parameters can be configured via the display: the encoder SCALE and OFFSET, the device address, the ALARM trigger points as well as 4-20mA parameters (if applicable).
Note that although the current reading is readily accessible from the display, the setup parameters are in fact password-protected thus ensuring the integrity of your results. The auto shut-off feature conserves energy.
Note that models equipped with the /4-20 feature must be ordered with the display option.

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