Work Areas - Omron SYSMAC CVM1 Series Operation Manual

CIO (Core I/O) Area
! Caution
Word Reservations

3-3-2 Work Areas

36
There are two ways, however, to change the I/O table registered in memory. One
is to allocate words to a slot that is not currently being used. This method is de-
scribed below in Word Reservations.
The other way is to perform the I/O Table Registration operation again. When
this is done, all I/O words will be reallocated according to the Units mounted to
the Racks at the time. If the number of words allocated to any one slot changes,
all word allocations past that slot will also change, requiring that the program be
changed to allow for this.
Sometimes program changes can be avoided when a Unit is removed from a
Rack or you know that you are going to have to add a Unit later by reserving
words. Although designed to enable slot reservations for future use, a slot reser-
vation can be left permanently to prevent what could be extensive program
changes.
Always be sure to change word and bit addresses in the program whenever a
change to Units on a Rack affects word allocations. Failure to do so may cause
improper I/O operations.
Words can be reserved at a certain slot for future use either by mounting a
Dummy I/O Unit to the slot before performing the I/O Table Registration opera-
tion or by performing an I/O Table Change operation after performing the I/O
Table Registration operation.
A Dummy I/O Unit provides settings to designate word types (input or output)
and length (one, two, or four words). After I/O Table Generation has been per-
formed and a Dummy I/O Unit has been allocated the words designated by these
settings, it can be replaced at any time with a Unit that requires the same type
and number of words, e.g., if a Dummy I/O Unit is set for two input words, it can
be replaced with any 24- or 32-point Input Unit or any other Unit that requires two
input words.
Once an I/O table has been registered, it can be changed using the I/O Table
Change operation described in SSS Operation Manuals. This operation can be
used to reserve up to four input words, output words, or non-defined words at a
time. The I/O Table Change operation must be performed after the I/O Table
Registration operation. If I/O Table Registration is repeated, all word reserva-
tions will be cancelled, and I/O Table Change will have to be repeated.
There are three Work Areas available in PC memory. Words and bits in the Work
Areas can be used in programming as required to control other bits, but are not
used for direct external I/O. Other bits and words in the CIO Area which are not
being used for their intended purpose can also be used as work words and work
bits. Actual application of work bits and work words is described in Section 4
Writing Programs.
Work words and bits are reset when power is interrupted or PC operation is
stopped, but they are not reset when a FALS error instruction is executed in the
program.
Work words
CIO 0128 to CIO 0199 (72 words)
CIO 1964 to CIO 1999 (36 words)
CIO 2064 to CIO 2299 (236 words)
Work bits
CIO 012800 to CIO 019915 (1,152 bits)
CIO 196400 to CIO 199915 (576 bits)
CIO 206400 to CIO 229915 (3,776 bits)
Section 3-3