ProSoft Technology MVI46-MBP - Manual (Page 47)

Reference MVI46-MBP ♦ SLC Platform
Modbus Plus Communication Module
ProSoft Technology, Inc. Page 47 of 101
February 19, 2008
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
100 Place a zero in this word after the SLC has processed the pass-
through message block 1
This will inform the module that the command has been processed and can be
cleared from the pass-through queue.
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.
Offset Description Length
100 9959 1
101 Number of word registers in Modbus data set 1
102 Starting word address for Modbus data set 1
103 to 152 Modbus data set 50
153 to 202 Bit mask to use with the data set. Each bit to be considered with
the data set will have a value of 1 in the mask. Bits to ignore in
the data set will have a value of 0 in the mask. 50
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
100 Place a zero in this word after the SLC has processed the pass-
through message block. 1
This will inform the module that the command has been processed and can be
cleared from the pass-through queue.