C500 Masters; Unit Numbers And I/O Word Allocation - Omron WIRED REMOTE I-O System Manual

Unit Numbers and I/O Word Allocation

Terminator
3-2-1

C500 Masters

Setting Slave Unit Numbers
and Terminators
Setting Remote Terminal
Words
Word Multipliers in C1000H
and C2000H Systems
26
In either case, allocations start from the lowest word starting on the left side
of the CPU Rack. When a Master is reached on a Rack, allocation jumps to
the leftmost Unit mounted on the first Slave Rack connected to the Master,
and then to the second Slave Rack, etc, until the terminator is reached. Then
allocations return to the Unit following the Master and continue across the
CPU Rack and Expansion I/O Racks until all the Units on all Racks have
been allocated. Details on and examples of allocation are provided below.
Words for Units not mounted to Racks (i.e., Remote Terminals) are not deter-
mined as described above, but according to switch settings on the Units, as
described below.
There must be one terminator set for each Master, and it must be the Unit at
the opposite end of the I/O bus from the Master.The terminator may be a
Slave or a Remote Terminal. The Master checks for a terminator immediately
upon power application. If the terminator is properly set, the other Units con-
nected to the I/O bus are acknowledged. All following operation is based on
this initial check. Therefore, if a Unit is not attached properly or if the power
to a Unit is not on when this check is performed, that Unit will be ignored dur-
ing actual operation.
Because more than one Slave can be attached to each Master, Unit number
settings are necessary to distinguish the Slaves. Unit numbers 0 through 7
can be set for C1000H and C2000H, Slaves; unit numbers 0 and 1, for all
others. The Slave assigned unit number 0 is referred to as Slave #0; the
Slave assigned unit number 1, as Slave #1, etc. The same unit number can-
not be used on more than one Slave under the same Master. Setting unit
numbers other than those listed above will prevent Slave operation.
Set the Slave directly connected to a Master as Slave #0, the Slave con-
nected to Slave #0 as Slave #1, and so on. Setting unit numbers and a termi-
nator is necessary for every Master, even when only one Slave is connected.
Refer to Section 4 Switch Settings for details on setting procedures.
I/O Units can be mounted to Slave Racks in any location desired numbers are
automatically allocated left to right in the order the I/O Units are mounted.
A PC I/O word must be allocated for each Remote Terminal connected in the
System; words are not automatically allocated. Any word from 0 through 31
can be set in all Systems but C120 Systems, where words between 0 and 15
must be set.
In C1000H and C2000H Systems, words 0 through 127 are allocated by the
PC's CPU Unit to enable use of up to 128 words even though actual word
settings are from 0 through 31. This is achieved by combining word settings
with word multipliers, which are explained next.
Because the C1000H and C2000H PCs can handle up to 2,048 points (or
128 words), words 32 to 127 of these PCs cannot be allocated without some
identification other than word settings. It is therefore necessary to assign
word multipliers to the Masters to which Remote Terminals are mounted and
identify the words with these multipliers as well. These numbers run from 0
through 3.
Word numbers, word settings, and word allocations are related as shown by
the following equation:
I/O word allocation = (32 words x word multiplier) + (word set on Unit)
Section 3-2