Specifications

IP 240 Positioning
BCD representation
If you require BCD-coded data for the purpose of documentation, definition or post-processing,
you may choose this form of representation instead of binary. Position numbers and distance
values for position 0, however, cannot be represented in BCD.
”1111” is entered in the high-order nibble (half-byte) as the sign (SG) of a negative number. A
nibble (also called a half-byte or tetrad) is the term used for the four high-order or the four low-
order bits in a byte.
Note
The IP 240 module firmware has to carry out format conversions to write and read
BCD-coded data, which on-loads the firmware's cycle for a data interchange
( Chapter 12, ”Response Times”).
The selected form of numerical representation must be taken into account for both data inter-
change using standard function blocks FB 167 and FB 168 and direct data interchange.
10.3.1 Specifying the Numerical Representation (BCD)
Configuring parameter BCD for FB 167 is used to specify the required form of numerical repre-
sentation:
: JU FB 167
NAME : STRU.POS
:
:
BCD : KY x,y x or y=0 Numbers in binary
x or y=1 Numbers in BCD
In
order to enable the numerical representation to be matched to the relevant requirements, a dis-
tinction was made between two data areas which are assigned as follows to parameters x and y:
x parameter y parameter
Position values for positions 1 to 254 Position value for position 0
Distance values for positions 1 to 254 Zero offsets
Range limit value for the rotary axis Actual value
Final value, (= actual value stored when
using ”Synchronization with external
control signal” as synchronization method)
Note
The position numbers and the distance values for position 0 are always interpreted
as unsigned binary numbers. BCD representation is not possible.
EWA 4NEB 811 6120-02a 10-11