
83
Details of the Data Exchange Methods
Section 6-3
2.
The IOWR instruction is structured as shown below for the CS1-series
PCs. The number of write words must be specified as a hexadecimal value.
3.
The data set in words n+8 and n+9 by PC QREAD is used only as monitor
data by the CPU Unit. The data that is actually transferred is specified in
an operand of the IOWR instruction. This aspect of operation differs from
that of the PC READ@ command, which reads data from the operand
specified for it. For the CS1 Series, the range that can be addressed for PC
QREAD differs from the range for IOWR, making it necessary to use dum-
my addresses when executing PC QREAD if it cannot address the required
words directly. (The CPU Unit will not monitor the words when dummy ad-
dresses are used.) In the above example, the address of the first word,
D07000 cannot be specified for PC QREAD even though it can be speci-
fied for IOWR. Here, a dummy address, like @D,0, can be used for PC
QREAD.
PC QWRITE (Combined
with IORD (#FD00))
The ASCII Unit sends an IORD Request Flag to the CPU Unit by bit 14 of IR/
CIO n + 5. When the CPU Unit detects the ON status of the flag, it will execute
the IORD instruction. Based on IR/CIO n + 8 and n + 9, it reads the words
from the ASCII Unit.
1,2,3...
1.
At I/O refresh, the ASCII Unit sends an IORD Request Flag to the CPU
Unit by the system.
2.
Data is prepared for transmission from the specified variable by the PC
QWRITE command.
3.
Data is read from the ASCII Unit when the IORD (#FD00) instruction is ex-
ecuted in the ladder diagram.
IOWR (223)
#FD00
D00300
#00030000
0003 0000
Unit No.
No. of write words
(Hex)
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