Beckhoff KL2521 Series, Documentation

Page: 23 / 43

Mounting and wiring
KL2521 23 Version: 2.1
Connection to optocoupler (with external supply voltage)
For connection to inputs with a large input resistance, an external supply voltage (up to 24 V) can be used
with the EL2521-0024 in order to create the necessary current.
Note
Operation with an external supply voltage is dependent on the hardware ver-
sion
The operation with an external supply voltage depends on the hardware version of the ter-
minal:
• You can use the standard variant KL2521-0000 for this up to hardware version 03.
• From hardware version 04 this is only possible with the special variant KL2521-0024,
which was specially optimized for this application!
However, since the KL2521-0024 has no internal supply voltage (5 V) it is not suitable
for connection to RS485/RS232 receivers or optocouplers without an external supply
voltage.
• KL2521-0000 up to hardware version 03
Fig. 15: KL2521-0000 up to hardware version 03 - wiring with external power source
• Instead of hardware version 04 (or higher), use the special variant KL2521-0024
Fig. 16: KL2521-0024 - wiring with external power source
See chapter Documentation issue status [
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7] for the determination of the hardware version