BEI Sensors MHK5 Absolute Hollow Shaft Encoder - Manual (Page 14)

4.1.6 Total measuring range
The parameter „total measuring range“ is used to
adapt the measuring range of the encoder to the
real measuring range of the application. The
encoder counts up until the position value has
reached the programmed total resolution and starts
with 0 again.
Example: 100 steps are programmed for each
revolution (parameter „measuring units per
revolution“) and the total resolution is set to 12800. Then the encoder counts up to 11799, starts with
“0” again after 128 revolutions, counts up to 11799,
and so on.
Note: With many software tools it is necessary to
divide the value into high and low word, refer to
page 35.
When choosing the total resolution the following
rule has to be observed:
If “steps per revolution” are set to “n” the parameter total resolution must not cause periods longer than
the maximum (physical) number of revolutions (see type label), i.e. that the programmed total resolution
of a 4096 revolution multiturn encoder must be less than 4096 x the programmed number of steps per
revolution (the programmed total resolution of a 16384 revolution multiturn encoder must be less than
16384 x the programmed number of steps per revolution):
Total resolution < measuring units per revolution x real number of revolutions (physical)
If this rule is disregarded the encoder will indicate a parameter error and it will not enter the data
exchange mode.
With older versions a further rule had to be
observed (see below). If this rule was ignored,
problems occurred when using the device in
endless operation (when crossing the physical
zero point). With new devices (software version
3 Generation A1 or higher) this problem is
solved by an internal software routine. For that
reason the 2
nd rule can be ignored if a new
device is used.
Note: The internal software routine only works if the
encoder is in operation. If it is necessary to turn the
encoder shaft more than 1024 revolutions without
power supply this can lead to problems (the internal
routine will not work without power supply). In this
case the following rule should be observed even with
new devices:
The period, i.e. “Total resolution” / “measuring units” per revolution must be an integer and it must fit an
integer number of times (integer multiple) into 4096. So the following equation must apply:
(4096 x measuring units per revolution) / Total resolution = integer
Octet 14 15 16 17
Bit 31 – 24 23 – 16 15 - 8 7 - 0
Data 2 31 to 2 24 2 23 to 2 16 2 15 to 2 8 2 7 to 2 0
Programmed total measuring range in steps
Page 14 BEI Sensors Profibus Manual serie M Revision 03/10