Data Exchange With Cpu Unit - Omron SYSMAC C Series Operation Manual

Data Exchange with CPU Unit

9-3

Data Exchange with CPU Unit

Overview
Two-word Operating
Mode
The WRIT and READ
instructions are used
to directly access RAM
in the Analog Output
Unit.
I/O words allocated for a
Special I/O Unit
Note This value is not used when more than one word is written by the WRIT instruction.
This section describes differences in data exchange with the CPU Unit between
two-word and four-word operating modes. The two/four-word operating mode
short-circuit pins on the front panel of the Unit are used to switch between two-
word and four-word operating modes.
The I/O READ and I/O WRITE instructions, READ and WRIT, are used to directly
access RAM in the Analog Output Unit. More than one word can be read and
written at a time. Data is exchanged when an instruction is executed.
CPU Unit
Data memory, etc.
(See
(ex. 01)
note)
Written
by WRIT
Read by
READ
Word n
Word n+1
Instead, data in the first write word is used as the first RAM address.
Analog Output Unit
Address
Address (ex. 08)
Section
RAM Data:
Addresses 01 to 08 contain the data
for 8 output points. Other addresses
contain the scaling upper and lower
limits, upper and lower limits,
biary/BCD mode settings, and other
parameters/flags.
8 analog output points
Read Pointer:
This pointer indicates the first read
address in RAM of the Analog
Output Unit.
– This value is set each time one
word is written by the WRIT
instruction (see note).
– This value specifies the first
address of the read source when
data is read by the READ
instruction.
Parameter Update Request Bit,
EEPROM Write Bit, etc.
Status flags, such as Invalid
Data Received Flag
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