Omron CJ1W-PRT21 - I;O Data Format

3-5
3 Data Exchange with the CPU Unit
CJ-series PROFIBUS Slave Unit Operation Manual for NJ-series CPU Unit (W510)
3-3 I/O Data Format
3
3-3 I/O Data Format
The CJ1W-PRT21 allows the user to select between two methods to map the word-oriented CPU data
to the essentially byte-oriented PROFIBUS-DP messages. The default method is Motorola format (Big-
Endian), which allows easy data exchange with other OMRON PROFIBUS-DP devices. For communi-
cation with other manufacturers’ devices, in some cases it may be more convenient to select Intel for-
mat (Little-Endian).
 Motorola (Big-Endian)
By default, the most significant byte of a CPU data word will be mapped to an even byte in the PRO-
FIBUS-DP message, the least significant byte is mapped to an odd byte, e.g.
 Intel (Little-Endian)
Alternatively, selecting Intel format will result in:
Additional Information
Variable *_SlavOutEndianMdSta indicates how the data bytes of a PROFIBUS data telegram are
mapped to Host CPU data words (see section 3-7-2 Slave Output Data (*_SlvOutSta))
• 0: Motorola (high byte first),
• 1: Intel (low byte first).
CPU Data Area PROFIBUS-DP Message
Bit # Bit #
Word 15 to 8 7 to 0 7 to 0 Byte
8 9 0
0 8 9
A B A B 1
C D 2
1C D
E F E F 3
CPU Data Area PROFIBUS-DP Message
Bit # Bit #
Word 15 to 8 7 to 0 7 to 0 Byte
0 8 9
A B A B 0
8 9 1
1C D
E F E F 2
C D 3