Rockwell Automation 1771-IS 5V DC INPUT MOD - Manual (Page 38)

Programming and Operation
Chapter 3
3-19
length: the number of words to be transferred can be 0-7 depending on
the number of switch assemblies. (03)
module address: rack, module group and slot number where 1 =
HIGH = upper slot, 0 = LOW = lower slot. (121)
control file address: location of a 10-word file necessary for block
transfer read and write operations, contains the module address in
binary, the address of the data file and the block transfer status/control
bits. (FB002:0010)
data file address: location of the source or destination of block
transfer data, generally equal in length to the maximum number of
transfer words. (FD002:0012)
For additional information on programming block transfer instructions,
refer to paragraph titled “Other Programming Considerations, PLC-2
Family and PLC-3” and the Programming and Operation Manual for the
PLC-3 processor.
Programming Example, PLC-3
To program block transfer with a PLC-3 processor, you must create a
control file and a data file (Figure 3.9). The control file can be located
anywhere in the binary section of the processor data table. The data file
for thumbwheel switches should be entered in the decimal section of the
processor data table; the data file for discrete switches in the binary
section of the processor data table. Neither block transfer file should
overlap other assigned storage words.
This example is similar to the one described in paragraph titled
“Programming Example, PLC-2 Family,” except that the rung is
programmed for recurring block transfers. Three words of data are used
to transfer the settings of two 4-digit thumbwheel switches. The settings
are 9751 and 8642 for thumbwheel switch assemblies 1 and 2,
respectively. (The first word is reserved for diagnostic data.) The module
is located in the upper slot of module group 2 in I/O rack 1. The
explanation of the single programming rung is that described for block
format instructions in paragraph titled “Programming Example, PLC-2
Family.”