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401-405 SERIES - 7 -
the range of 5-28 Vdc from a source external to the flow meter. The loop supply can be the same supply
as that for the instrument power or it can be an isolated loop supply.
Figure 2-3 shows a typical setup using the same supply. This method requires a jumper from pin 2 to
pin 4 on the terminal strip while connecting pin 3 to a wire that carries this signal to the indicator (for
example, a process ammeter, data acquisition system, or PLC board). To complete the current loop,
another wire carries the return signal from the flow indicator back to the negative end of the input
supply.(Alternatively, the loop current can be measured on the “high potential side” by connecting the
indicator between the pins 2 and 4 while connecting pin 3 to pin 1.)
Figure 2-4 shows an arrangement using a separate loop supply which is isolated from the instrument
power supply.