ifm electronic RN3001 - Manual (Page 18)

Encoder with Profibus interface
18
10.1.7 Physical measuring steps
Octet 35 36 37 38
Bit 31���24 23���16 15���8 7���0
Data 2 31 ���2 24 2 23 ���2 16 2 15 ���2 8 2 7 ���2 0
Physical measuring steps
This parameter is evaluated by the device if the option [Physical impulses] was
selected as reference to the requested measuring steps� By means of the physical
measuring steps a gearbox factor can be freely set� Here it is defined how many
measuring steps (requested measuring steps) are to be provided on a defined
sub-measuring range� This option is useful if "odd" scaling factors are to be
entered�
Example
The encoder is to provide 400 steps over 3 revolutions�
With the reference [Desired measuring units per revolution] this number of steps
cannot be set (the [Desired measuring units] parameter should contain the value
133�333; however only integers can be entered)�
Remedy
The physical measuring steps are selected as reference for the requested
measuring steps�
The number of the physical measuring steps over the requested measuring range
is determined on the basis of the actual (physical) resolution of the device (type
label)� For this absolute encoder with 12-bit standard resolution this would in this
case be
4096 steps/revolution x 3 revolutions = 12288 steps
This value is now entered as [Physical impulses] parameter; the actually required
number of steps of 400 is entered at [Desired measuring units]� The encoder
now provides 400 steps over a measuring range of 12288 physical steps (i�e� 3
revolutions)�
Note: With many projection tools it may be required to split the value into high
word and low word�
10.1.8 Encoder type
The type of encoder (singleturn or multiturn) is defined in bit 1 of octet 39� This
is done automatically when the encoder class is selected� The user only has to
consider this parameter if parameters are set directly in the hexadecimal code�
Octet 39 bit 1 Type
0 Singleturn
1 Multiturn