Omron CVM1D, Operation Manual

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38
The Holding Area retains status when the operating mode is changed, power is
interrupted, or PC operation is stopped.
Holding Area bits and words can be used to preserve data whenever PC opera-
tion is stopped. Holding bits also have various special applications, such as
creating latching relays with the KEEP instruction and forming self-holding out-
puts. These are discussed in Section 4 Writing Programs and Section 5 Instruc-
tion Set.
3-3-6 CPU Bus Unit Area
Two types of external bus are provided for CVM1, CVM1D, and CV-series PCs:
the high-speed CPU bus (S Bus) and the I/O bus. Units that connect to the CPU
bus on the CPU or Expansion CPU Rack are called CPU Bus Units and include
the SYSMAC NET Link Unit, SYSMAC LINK Unit, Controller Link Unit, Host Link
Unit, CompoBus/D Master Unit, SYSMAC BUS/2 Remote I/O Master Unit, BA-
SIC Unit, and Personal Computer Unit.
CPU Bus Unit Area addresses range from CIO 1500 through CIO 1899. These
400 words are divided into 16 groups of 25 words each. These are allocated to
CPU Bus Units according their unit number settings as shown in the following
tables.
Unit # 0 1 2 3 4 5 6 7
CIO
words
1500
to
1524
1525
to
1549
1550
to
1574
1575
to
1599
1600
to
1624
1625
to
1649
1650
to
1674
1675
to
1699
Unit # 8 9 10 11 12 13 14 15
CIO
words
1700
to
1724
1725
to
1749
1750
to
1774
1775
to
1799
1800
to
1824
1825
to
1849
1850
to
1874
1875
to
1899
An additional1600 words in the DM Area (D02000 to D03599) are provided for
CPU Bus Units. The particular function of words allocated to the Unit depends on
the CPU Bus Unit being used.
3-3-7 CompoBus/D Areas
I/O bits allocated to CompoBus/D correspond to external I/O points on the de-
vices connected to the CompoBus/D device network. Refer to CompoBus/D
(DeviceNet) Operation Manual (W267) for further information.
Words Bits
CIO 1900 to CIO 1963 (64 words) CIO 190000 to CIO 196315 (1,024 bits)
CIO 2000 to CIO 2063 (64 words) CIO 200000 to CIO 206315 (1,024 bits)
Note Bits not used for CompoBus/D can be used as work bits.
3-3-8 SYSMAC BUS Area
I/O bits allocated in the SYSMAC BUS Area correspond to external I/O points on
I/O Terminals, Optical I/O Units, or I/O Units mounted to Slave Racks that are
connected to SYSMAC BUS Remote I/O Master Units (RM). Up to 8 Masters
can be connected to the PC and the total number of I/O points in the SYSMAC
BUS System must not exceed 2,048 (128 words).
Unit numbers are assigned to Masters automatically when the I/O Table is regis-
tered or edited, according to the order in which the Masters are mounted (taking
into account rack number settings). The first word allocated to each Master can
be changed with the PC Setup using the SSS.
CIO (Core I/O) Area
Section 3-3