Siemens SINUMERIK 828D Programming Manual page 455

Binary constants
Constants can also be interpreted in binary format. In this case, only the digits "0" and "1"
are used.
Binary constants are enclosed in single quotation marks and start with the letter "B", followed
by the binary value. Separators are allowed between the digits.
Example:
Program code
$MN_AUXFU_GROUP_SPEC='B10000001'
Note
The maximum number of characters is limited by the value range of the integer data type.
Fundamentals
Programming Manual, 07/2010, 6FC5398-1BP40-0BA0
Comment
; The assignment of binary constants sets
Bit0 and Bit7 in the machine data.
Other information
15.6 Constants
455