87
Figure 118: Read the Inverter’s Output Frequency Register
8.3.5 SLC-5/05
Example:
Multiple MSG Instructions
At times, reading from different groups of registers may be necessary. For example, a specific
application may require some registers located in various disjoint locations in the register map. To
accomplish this task efficiently, multiple MSG instructions can be implemented in the PLC program.
The configuration and execution for implementing multiple MSG instructions is in general identical to that
required for implementing just one MSG instruction. Each MSG instruction will require its own message
control file. In the case of read MSG instructions, more than one instruction may use the same data file
to store the received register values, but the storage locations must not overlap. Figure 119 shows an
example of two MSG instructions, each accessing different target integer files. It is evident from this logic
that N20 and N21 are the two independent message control files created for these instructions.
Figure 119: Multiple MSG Instructions
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