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I/O Data Conversions Appendix D
D-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.
D-5 Date and 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 tat workable data is transferred from PROFIBUS to the PLC memory, these data types are
treated as 16-bit word data.
Char 1
Char 2
PLC Data area PROFIBUS
Bit 07 Bit 00
Char n-1
Char n
Char 2Char 1
Bit 15 Bit 00
Word 0
Char nChar n-1Word m
ASCII Text string
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