Beckhoff EL34 Series Documentation page 150

Commissioning
Fig. 154: Connection of externally supplied sensors
Classification of the Beckhoff terminals/ boxes - Beckhoff 0/4-20 mA terminals/ boxes (and related product
groups) are available as differential and single-ended terminals/ boxes (and related product groups):
Single-ended
EL3x4x: 0-20 mA, EL3x5x: 4-20 mA; KL and related product
groups exactly the same
Preferred current direction because of internal diode
Designed for the connection of externally-supplied sensors with a
3/4-wire connection
Designed for the connection of self-supplied sensors with a 2-wire
connection
150
Differential
EL3x1x: 0-20 mA, EL3x2x: 4-20 mA; KL and related product
groups exactly the same
Preferred current direction because of internal diode
The terminal/ box is a passive differential current measuring de-
vice; passive means that the sensor is not supplied with power.
Version: 1.5 EL34xx