Description
XAI Analog inputs
XAO Analog outputs
XDI Digital inputs, Digital input interlock (DIIL)
XDIO Digital input/outputs
XD2D Drive-to-drive link
XD24 +24 V output (for digital inputs)
XETH Ethernet port (eg. for PC communication)
XPOW External power input
XRO1 Relay output RO1
XRO2 Relay output RO2
XRO3 Relay output RO3
XSTO Safe torque off connection (input signals)
XSTO OUT Safe torque off connection (to inverter modules)
X13 Control panel / PC connection
X485 Not in use
V1T/V1R, 
V2T/V2R
Fiber optic connection to inverter modules 1 and 
2 (VxT = transmitter, VxR = receiver)
V3T/V3R
…
V7T/V7R
Fiber optic connection to inverter modules 3…7 
(BCU-12/22 only)
(VxT = transmitter, VxR = receiver)
V8T/V8R
…
V12T/V12R
Fiber optic connection to inverter modules 8…12 
(BCU-22 only)
(VxT = transmitter, VxR = receiver)
SD CARD Data logger memory card for inverter module 
communication
BATT OK Real-time clock battery voltage is higher than 
2.8 V. If the LED is off when the control unit is 
powered, replace the battery.
FAULT The control program has generated a fault. See 
the firmware manual of the inverter unit.
PWR OK Internal voltage supply is OK
WRITE Writing to memory card in progress. Do not 
remove the memory card.
XDI
XSTO
X485
XD2D
XRO1
XRO2
XRO3
XDIO
XD24
XSTO
OUT
XAI
XAO
XPOW