
82
Details of the Data Exchange Methods
Section 6-3
2.
The IORD instruction is structured as shown below for the CS1-series
PCs. The number of read words must be specified as a hexadecimal value.
6-3-5
Data Exchange Method No. 5
On a trigger from the ASCII Unit, the CPU Unit reads/writes memory data to
the ASCII Unit by executing an IOWR/IORD (#FD00) instruction.
PC QREAD (Combined
with IOWR (#FD00))
The ASCII Unit sets an IOWR Request Flag in the CPU Unit in bit 15 of IR/
CIO n + 5. When the CPU Unit detects the ON status of the flag, it will execute
the IOWR (#FD00) instruction. Based on IR/CIO n + 8 and n + 9, it writes the
specified words to the ASCII Unit.
1,2,3...
1.
At I/O refresh, the ASCII Unit sends an IOWR Request Flag to the CPU
Unit by the system.
2.
Data is written to the ASCII Unit when the IOWR (#FD00) instruction is ex-
ecuted in the ladder diagram.
3.
As a result of the PC QREAD command, the received data is read to a
specified variable.
The following example is for a C200HX/HG/HE PC.
Note
1.
IORD and IOWR instructions cannot be used for ASCII Units on Slave
Racks.
IORD (222)
#0000
#00040000
D00300
0004 0000
Unit No.
No. of read words
(Hex)
CPU Unit
ASCII Unit
ASCII
Busy Flag
No. of write
words (BCD)
Unit No.
128 words max.
Control code
DM 0300 set as
first word
1. IOWR Request Flag (trigger)
1. Allocated words in IR Area
3 words from
DM 0300
ASCII Unit on standby until
completion of IOWR execution.
I/O refresh
DM 0300
0301
0302
Allocated I/O
3 words
2. IOWR instruction
Transfer at IOWR execution
3.
At the same time
I/O refresh
10515
IOWR
#FD00
DM0300
#0003
0003
PC QREAD "@D, 300, 3, S3H4"; B (1)
n+5
@
15
n+8
n+9
n+8
n+9
B (1)
B (2)
B (3)
0 0 0 3
0 3 0 0
0 3 0 0
0 0 0 3
10500
n + 5 bit 00
(See note 2)
(See note 3)
@
Содержание C200H-ASC11
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