There is no difference between HMI and MMI.
MMI stands for Man Machine interface.
HMI stands for Human Machine Interface.
Then there will rise a question why there are two terms.
In the ewarlier days only men used to work in any control
room. But now a days womwn are also working in all Controll
rooms.Hence the word HMI has been ome in usage.Just to
avoid any doubt that in control both men and women can work.
Every application requires selection of the right type of
component and shaft/bushing configuration.
Whether the component is a precision potentiometer, panel
control or rotary encoder, selection of the
right shaft/bushing configuration will yield the optimum
performance of the component in its
There are two general categories of applications that should
be considered when selecting a component. These categories
are Human-to-Machine Interface (HMI) and Machine-to-Machine
HMI applications commonly appear on the front panel of an
application as manual adjustments. These
devices are typically mounted to a panel (as shown in Figure
1) with a sleeve bushing and have a knob
mounted on the end of the shaft. In these applications, high
speed of rotation and shaft side load are
normally not encountered. On some models, a sleeve bushing
is available with front ball bearings
should the designer wish to have a very low shaft torque, or
front and rear ball bearings for
applications where the shaft will likely encounter up to 0.5
oz of side load due to an oversized knob or
other similar design factors.
Many MMI applications are position sensors where adjustments
will be made by mechanical interface.
Position sensor designs include hospital beds, dental
chairs, fluid control valves, elevators, automatic
doors and lift trucks. These sensors can also be used to
count rotations of a motor via a mechanical
coupling device. In MMI applications, a high speed of
rotation may be encountered along with a shaft
side load exerted by either a pulley or gear system. For
these applications, the front ball bearing option
or front and rear ball bearing option and servo mount
configuration (as shown in Figure 2) is highly
Configurations made for MMI applications may be used in HMI
applications where the designer
would like the additional robustness and extended rotational
life. However, configurations made for
HMI applications are not recommended for use in MMI applications
Answer no 5 seems to be correct with answer no 3. Intially
the machine interfaces are having limited capabilities and
then enhanced to higher levels. So answwer no 3 may be
taken as correct and while renaming while tech advancing
Answer no 5 must have been considered.
There was an another term calleed GUS: Global User Staion
But HMI stands dominating. MMI (favour towards men), GUs
(not specific for machine interface)