DI–720/DI–722/DI–730 Series User ManualAccessories89DI-5B42 2-Wire Transmitter Interface ModulesEach DI-5B42 2-wire transmitter interface module provides a single channel which accepts a 4 to 20 mA process cur-rent input and provides a standard +1 to +5V output signal (see block diagram). An isolated +20VDC regulatedpower supply is provided to power the current transmitter. This allows a 2-wire loop powered transmitter to bedirectly connected to the DI-5B42 without requiring an external power supply. The regulated supply will provide anominal +20VDC at a loop current of 4mA to 20mA.The DI-5B42 will provide a 1500V isolation barrier for non-isolated 2-wire field transmitters. It can also be usedwhen additional isolation is required between an isolated 2-wire transmitter and the input stage of the control roomcomputer.The voltage output is logic switch controlled, which allows these modules to share a common analog bus without therequirement of external multiplexers.The DI-5B modules are designed with a completely isolated computer side circuit which can be floated to ±50V fromPower Common, pin 16. This complete isolation means that no connection is required between I/O Common andPower Common for proper operation of the output switch. If desired, the output switch can be turned on continuouslyby simply connecting pin 22, the Read-Enable pin to I/O Common, pin 19.A precision 20Ω current conversion resistor is supplied with the module. All field inputs are fully protected fromaccidental connection of power-line voltages up to 240VAC. The module has a 3dB bandwidth of 100Hz. Signal fil-tering is accomplished with a six-pole filter, with two poles on the field side of the isolation barrier, and the other fouron the computer side.Ordering InformationMODEL INPUT RANGE OUTPUT RANGEDI-5B42-01 4mA to 20mA +1V to +5V
