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Block Transfer
Chapter 18
18-20
module is loaded into words 050-052. When block transfer is
complete, done bit 114/07 is set in the input image table byte. This
indicates the block transfer was successfully performed. The
processor then continues with the I/O scan and program scan.
3.
In rung 2, bit 114/07 is still on and a diagnostic bit is examined to
ensure the data read from the module is valid. Assuming the data is
valid, the diagnostic bit is on and the data is transferred from word
050 to 150. In rungs 3 and 4, the data in words 051 and 052 is
transferred to words 151 and 152 if the appropriate diagnostic bits
are on.
If you are using a 1770-T1 or -T2 industrial terminal to program a
processor and you want to perform block transfer, you must use the two
Get method.
The Block Transfer rung must be programmed in a certain format
(Figure 18.9). It consists of condition instructions that are optional, two
Get instructions and an Output Energize instruction.
Figure 18.9
Block Transfer Rung
WYZ
0RGST
XYZ
G
ABC
G
RGS
optional
10389–I
conditions
Here is an explanation of the optional conditions:
This Condition:
Examine the:
WYZ
First timer/counter address (accumulated area).
XYZ
Timer/counter address 100
8
higher than WYZ (preset area).
RGS
Location of the block transfer module (I/O rack, module group. and
module slot. S is a zero for the left slot and a 1 for the right slot.
For a 2slot module, S is always zero.
ABC
Starting address where data in transferred to/from.
0RGST
Output energize initiates Block Transfer.
0 = output byte
R = rack
G = module group
S = module slot
T = 6 for write operation; 7 for read operation
Two Get Method