current
The instrument varies its current output depending
what the sensor reads at the process.
from 4-20 ma, if the load at the plc
is 250 ohms you get 1-5 volts there.
The PLC senses this voltage standard normally.
If the wire breaks the DI-alarms that wire as broken
and you could shut down a dangerous process.
If there is a PLC which works from 2-10 volts
then its load to the instrument must be 500 ohms.
At the top : 500 ohms x 20 ma = 10 volts.
Bye.
The instrument varies its current output depending
what the sensor reads at the process.
from 4-20 ma, if the load at the plc
is 250 ohms you get 1-5 volts there.
The PLC senses this voltage standard normally.
If the wire breaks the DI-alarms that wire as broken
and you could shut down a dangerous process.
If there is a PLC which works from 2-10 volts
then its load to the instrument must be 500 ohms.
At the top : 500 ohms x 20 ma = 10 volts.
Bye.
