Block Transfer
Chapter 18
18-26
Setting the Number of Words to Transfer
Each block transfer module has a default value that specifies the maximum
number of words that can be transferred. Either the default value or some
lesser value can be selected. For bi-directional block transfers, use the
default value of the module. The default value varies from one kind of
module to another, consult the appropriate module documentation
for specifics.
When you what fewer words, set the number of words to be transferred by
programming support rungs. The number of words is stored in the upper
or lower Output Image Table byte that corresponds to the module’s
location in the I/O rack. The appropriate bits must be set On to specify a
binary value that equals the number of words to transfer (Figure 18.13).
These bits can be set On by programming unconditional Output Energize
or Output Latch instructions.
Figure 18.13
Setting the Number of Transfer Words
10385-I
0
0
5
Block Transfer Data
030
050
054
114
130
0
1
4
1
1
014
Bit 6 of 7 if a successful
block transfer occurred.
1
1 0 0 0 0
0
1 0 1
# Words
To Transfer
Bit Pattern
7 6 5 4 3 2 1 0
Default
1
2
3
4
5
62
63
64
0 0 0 0 0 0
0 0 0 0 0 1
0 0 0 0 1 0
0 0 0 0 1 1
0 0 0 1 0 0
0 0 0 1 0 1
1 1 1 1 1 0
1
0 0 0 0 0 0
1 1 1 1 1
Read 5 words from module
