Open terminating resistor
Closed terminating resistor
Connecting using a repeater
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
In order to connect HHU electrically and for communication along the MPI bus,
a distributor box is used.
The distributor box has an interface to the MPI bus, as well as a terminal block
for connecting EMERGENCY STOP, enable keys, handwheel and 24V power
If you wish to connect more than two HHUs to a bus segment or if the HHU can-
not be connected at the bus end, it is generally recommended to use a PROFI-
BUS repeater for connecting the HHUs.
If a HHU is connected to the bus ends, no repeater is required.
For a detailed description of the electrical and mechanical design, as well as for
the interfaces of the HHU module, please refer to:
Operator Components, Manual
Section: Handheld Unit and Distributor Box.
5 MPI Communication
5.6 Handheld unit (HHU)