Omron SYSMAC C Series Operation Manual page 166

Data Exchange with CPU Unit
Using the I/O WRITE Instruction, WRIT
The function of the WRIT instruction depends on the number of words trans-
ferred (1 or more than 1) as described below. When writing parameters and con-
version data directly to RAM in the Analog Operation Unit, set the number of
words transferred to a value greater than 1.
When executing the WRITE instruction with the First Cycle Flag, there is a possi-
bility that the Analog I/O Unit's internal processing may not be completed, and
the WRITE instruction is not executed. When executing the WRITE instruction
immediately after operation is started, use either of the following as the execu-
tion condition of the WRITE instruction:
• Bit 2 of word n+1 (A/D Write Completed Flag)
• A timer of at least 3 s.
All data written by the WRIT instruction is checked regardless of whether a func-
tion is enabled. If setting errors are detected, none of the data will be written.
Therefore, only the data required for settings should be written individually.
If a series of data containing the settings of the functions not to be used is written,
make settings so that the default values will be written as the settings for unused
functions. This must be done before executing the WRIT instruction.
When the Number of Words Transferred is 1
First allocated I/O address
Transfer source address
Number of words transferred = 0001
CPU Unit
Example:
Transfer source address
Always #0001
The content of D00100 is written to the Read Pointer (address 12).
CPU Unit
The I/O READ instruction, READ, uses the set value of the Read Pointer to read
data from the specified number of words starting from the specified address in
RAM.
The value of the Read Pointer remains valid until the next WRIT instruction is
executed with the number of words transferred is turned ON, until the power is
Set the value of the Read Pointer (address
12) for the Analog Output Unit. The content of
S is written to address 12. Use this instruction
in conjunction with the READ Instruction.
Analog Output Unit (Allocated I/O words: n, n+1)
Address
Pointer
Read
settings
Pointer
Allocated I/O words: 0002, 0003
Analog Output Unit
Address
Read
Pointer
Pointer
settings
Section 9-3
155