Handheld unit (HHU)
Prerequisites for start-up
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
Handheld unit (HHU), front
The following hardware components are required to start up the HHU:
The distributor box incorporates the MPI module interface, the HHU interface,
as well as a terminal block for connecting EMERGENCY STOP, enable keys,
handwheel and 24V power supply.
HHU connection cable
The HHU is connected to the distributor box using the HHU cable.
MPI bus cable
Under no circumstances may the MPI connector for connecting the HHU con-
tain an integrated bus terminating resistor, since a bus terminating resistor is
already integrated in the HHU.
5 MPI Communication
5.6 Handheld unit (HHU)