100 Unidrive M SI-PROFIBUS User Guide
Issue Number: 3
Table 14.23 shows an example set of data words for PPO 4 Word mode. This example
will write a value of 1553.9 rpm (32-bit value is 15539) to the digital speed reference 1
(Pr 01.021) to the drive.
Table 14.23 PPO 4 Word write requests example
Table 14.24 shows an example successful write response to the write instruction
illustrated above in Table 14.23.
Table 14.24 PPO 4 Word write response example
14.7.5 Limitations of non-cyclic data Mode 1 - CT Single Word
CT Single Word non-cyclic data uses only 1 word of data, however when used with data
alignment set to 32 (see section Cyclic data alignment on page 35) this requires two
16-bit words (a single 32-bit word). When used with data alignment set to 32 only the
lower 16 bits of the 32-bit word are used.
14.7.6 Using non-cyclic data Mode 2 - PPO 4 Word
Data consistency is important when using PPO4 word (Mode 2) non-cyclic data as each
non-cyclic message consists of four words. If there is data skew between any of the
non-cyclic words this could result in the wrong data value being written to the wrong
parameter.
The GSD file provides the PPO 4 Word which consists of four IN/OUT words with
consistency.
If non-cyclic data is required and the DP-V1 non-cyclic channel is not used then the non-
cyclic CT Single Word and/or the PPO 4 Word modules must be selected. A total of
eight different modules can be selected to configure the input and output configuration
of the node.
OUT data
word
Hex value
Function
b15-b12 b11 b10-b8 b7-b0
OUT word 0 0x8001 TASK ID = 8 0 MENU = 1
OUT word 1 0x1500 PARAMETER = 21 0
OUT word 2 0x0000 DATA HIGH word = 0
OUT word 3 0x3CB3 DATA LOW word = 15539
IN data
word
Hex value
Function
b15-b12 b11 b10-b8 b7-b0
IN word 0 0x5001
RESPONSE
ID = 5
0MENU = 1
IN word 1 0x1500 PARAMETER = 21 0
IN word 2 0x0000 DATA HIGH word = 0
IN word 3 0x3CB3 DATA LOW word = 15539
If the PPO 4 command is left in the data words, the write will be executed on every poll
of the network, effectively providing a continuous write. Care should be taken to ensure
the parameters for the write are set-up before the TASK ID is changed from 0 to prevent
incorrect data being written.
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