Pass-Through Formatted Block For Function 15 (9959) - ProSoft Technology CompactLogix MVI69E-MBS User Manual

MVI69E-MBS ♦ CompactLogix™ Platform
Modbus Serial Enhanced Communication Module

8.4.16 Pass-through Formatted Block for Function 15 (9959)

Block 9959: Pass-Through Formatted Block for Function 15
When the module receives a function code 15 in Pass-Through mode, the module writes
the data using block ID 9959 for multiple-bit data. First the bit mask clears the bits to be
updated. This is accomplished in Studio 5000 by ANDing the inverted mask with the
existing data.
Next, the new data ANDed with the mask is ORed with the existing data. This protects
the other bits in the INT registers from being affected. This function can only be used if
the Block Transfer Size parameter is set to 120 or 240 words.
Block 9959: Request from Module to Processor
Description
Offset
Read Block ID: 9959
0
Write Block ID: 9959
1
Length in words
2
Data address
3
Modbus Data
4 to 28
Bit mask to use with the data set. Each bit to be considered with the data set has
29 to 53
a value of 1 in the mask. Bits to ignore in the data set has a value of 0 in the
mask.
Spare
54 to (n-1)
Where n = 60, 120, or 240 depending on the Block Transfer Size parameter.
The ladder logic is responsible for parsing and copying the received message and
performing the proper control operation as expected by the Master device. The
processor must then respond to the Pass-Through control block with a write block with
the following format.
Block 9959: Response from Processor to Module
Description
Offset
Write Block ID: 9959
0
Spare
1 to (n-1)
This informs the module that the command has been processed and can be cleared
from the Pass-Through queue.
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Reference
User Manual
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