The Multi-Interface Board is an alternative to the output drivers supplied with the standard range of Deeter LVCS and LVCS HE and enables LVCS configurations that are not practicable with the standard drivers, plus additional features that are not available as standard.

The multi-interface board features:

  • 0-10V voltage output
  • 4-20mA current-loop output
  • 2x open-collector transistor outputs
  • serial communications link

Voltage output ranges other than 0-10V are available on request. Popular alternatives are 0-2V and 0-4V.

The current-loop output is the industry-standard 4 to 20mA. On power-up, the current will remain at 0mA if a fault is detected, e.g. LVCS stem disconnected.

The two transistor outputs have open collectors that can be pulled high to a maximum 40V. When on they can sink up to 50mA to the 0V rail and are protected from over-current. They can be used to directly drive a wide range of relays for pump or valve control1. Default switching thresholds are:

DO-1 on below 10%, off above 20%

DO-2 on above 90%, off below 80%

These settings are restored from non-volatile memory at power-up. They can be set to alternative levels at the factory on request, or changed by the user via the serial communications link.

The serial communications link allows communication with a PC for setting the transistor thresholds and enables remote monitoring or data-logging of the liquid level. A USB adapter cable is required which can be supplied by Deeter, together with sample PC software. Customers who wish to develop their own software should contact Deeter for further information.

The circuit board has a row of 8 screw terminals, in pairs. The labelling and functions are:

Label Function
Vin DC power supply +ve
0V DC power supply –ve
4-20mA + Current-loop output +ve
4-20mA – Current-loop output –ve
DO-1 Digital output 1
DO-2 Digital output 2
Vout 0-10V analogue voltage output +ve
0V 0-10V analogue voltage output –ve

The interface board takes a DC power supply between 14V and 30V. A diode protects against reverse polarity connection and a 500mA fuse protects against over-current. Normal quiescent current is less than 100mA.

1 For inductive loads fit an external transient suppressor.

Specifications

Power Supply

15-28VDC @ 50mA

(8-28VDC for 0-2V and 0-4V options)

Transistor Outputs

Max. voltage

Max. current

40VDC

50mA

Current Loop Output

4-20mA into

10?# to 1.2K?*

Voltage Output Range

0-10V

Interface

TTL Serial Comms

(USB Adapter)

Operating Temperature

0 – 70 °C

# At maximum operating voltage and temperature, the minimum load resistance increases to approximately 500 ohms. (An approximate formula is: Rload(min) = [Supply Voltage / 20mA] – [150C – Ambient Temperature] / 0.04C/ohm)

* Maximum load resistance is given by the formula: Rload(max) = (Supply Voltage – 2V) / 20mA

Datasheet