106 Rockwell Automation Publication 750COM-UM009A-EN-P - May 2017
Chapter 5 Using Explicit Messaging
Ladder Logic Program to Write Multiple Parameters
A Scattered Write message is used to write to multiple parameters. This write
message example writes the following values to these floating point (32-bit
REAL) parameters in a PowerFlex 755T drive, the values are written as Port
Number: Parameter Number - [Parameter Name]
See DPI Parameter Object on page 145
(Class code 0x93) or Host DPI
Parameter Object on page 163 (Class code 0x9F) for parameter numbering.
Table 13 - Example Controller Tags to Write Multiple Parameters
Figure 26 - Example Ladder Logic to Write Multiple Parameters
PowerFlex 755T Drive Parameter Write Value
10:1916 - [VRef Accel Time 2] 11.1 Sec
10:1918 - [VRef Decel Time 2] 22.2 Sec
10:1818 - [Preset Speed 5] 33.3 Hz
10:1819 - [Preset Speed 6] 44.4 Hz
10:1820 - [Preset Speed 7] 55.5 Hz
Operand Controller Tags for Scattered Write Message Data Type
XIC Execute_Scattered_Write_Message BOOL
MSG Scattered_Write_Message MESSAGE
IMPORTANT The drive saves parameter values that are written through Scattered Write
messages into the drives nonvolatile storage (NVS). The NVS allows only a
limited number of write cycles before it cannot store data reliably. To avoid
reaching this limit, do not use the Scattered Write messages for continuous
changes to parameter values.
If a parameter value must be changed continuously, you can use the
datalinks that are associated with the Logix controller's I/O connection, or
you can use individual parameter write messages that store the values that
are written to Random Access Memory (RAM) rather than NVS (see class
0x93, instance attribute 10, on page 147
).
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