ProSoft Technology MVI69-MCM - Manual (Page 132)

Reference MVI69-MCM ♦ CompactLogix or MicroLogix Platform
User Manual Modbus Communication Module
Page 132 of 167 ProSoft Technology, Inc.
March 22, 2011
Function 15
When the module receives a function code 15 when in pass-through mode, the
module will write the data using block ID 9959 for multiple-bit data. First the bit
mask clears the bits to be updated. This is accomplished 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.
For MVI69-MCM firmware versions 1.21 and newer only:
Offset Description Length (words)
0 9959 1
1 9959 1
2 Number of Words 1
3 Word Address 1
4 to 53 Data 1
54 to 104 Mask.
Note: For block transfer size = 60, the mask bits are limited
to the count of 6 words (96 bits). Therefore, the practical
data size limit is also 96 bits.
50
105 to 180 Spare 50
For MVI69-MCM firmware versions earlier than 1.21:
Offset Description Length (words)
0 0 1
1 9959 1
2 Write Block ID 1
3 Number of Words 1
4 Word Address 1
5 to 55 Data 50
56 to 105 Mask 50
106 to 180 Spare 15
The ladder logic will be 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.
Offset Description Length (words)
0 9959 1
1 to n Spare
This will inform the module that the command has been processed and can be
cleared from the pass-through queue.