Omron SYSMAC CS Series Operation Manual page 266

I/O Data Conversions
C-4 Text String Data Conversion
PROFIBUS defines ASCII text strings data type. It is transferred over the network as a string of characters. In
order to maintain a readable string in the PLC memory, the data is converted to fit the odd character in the
Most Significant Byte of the words, and the even characters in the Least Significant Byte of the words. The
string is stored on ascending word addresses in PLC memory. The figure below illustrates the conversion.
Note m = (n-1)/2, rounded to the next lowest integer.
If the number of text characters is even, all bytes will fit in the words, but one additional word will be set to
0000. If the number of bytes is odd, the last byte of the sequence will be mapped to the high-byte of the last
word. The low-byte of the last word will be padded with a 0.
C-5 Date / Clock Time Data Conversions
Date, Time and Time Difference data types as defined in PROFIBUS are not supported by the CS1/CJ1-series
PLC. To ensure that workable data is transferred from PROFIBUS to the PLC memory, these data types are
treated as 16-bit word data. The figure below illustrates the conversion.
Bit 15
Word 0
Word 1
Word 2
Word 3
Date and Time information is coded as defined by the PROFIBUS DP standard. The figure and the table below
define the format as it is stored in the PLC memory.
Note The grey areas in the figure above denote reserved bits, which are always set to 0.
PLC Data area
Bit 15
Word 0 Char 1 Char 2
Word m Char n-1 Char n
PLC Data area
Bit 00
Byte 1 (MSB) Byte 2 (LSB)
Byte 3 Byte 4
Byte 5 Byte 6
Byte 7 00
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Word 0
Word 1 Time [min]
Word 2 Day [wk] Day [month]
Word 3 Year
PROFIBUS
Bit 07 Bit 00
Char 1
Char 2
Bit 00
Char n-1
Char n
PROFIBUS
Bit 07 Bit 00
Byte 1 (MSB)
Time [ms]
Byte 2 (LSB)
Byte 3 Time [min]
Byte 4 Time [hrs]
Byte 5 Date [day of week/month]
Byte 6 Date [month]
Byte 7 Date [year]
Time [ms]
Time [hrs]
SU
Month
Appendix C
ASCII Text string
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