APP NOTE: Re-transmitting a Signal Output from a Controller or a D/A Card

Application Note 3: 600T

Problem: Retransmitting a signal output from a controller or a D/A card.

Solution: Use either a model 671T-0600 (single channel) or 672T-0600 (dual channel) transmitter.

IMPORTANT:  The 671T transmitter is an input loop powered current isolator. Its input voltage burden is normally a function of its output voltage drop and is computed as 4.9V+Iout*Rout. If the output load resistance Rout is excessive relative to the input loop voltage, or Rout is open-circuited, the input voltage burden may increase up to the limit of available input loop voltage. Consequently, if there are any loop-powered transmitters connected in series in the 671T input loop, this output loop fault can pinch-off excess input loop voltage, reducing the available voltage to power any series-connected transmitters in the loop, potentially causing them to lose regulation of the input loop current.  You could select a different current isolator than 671T, or a different series transmitter that is separately powered to avoid this fault condition.