84
Details of the Data Exchange Methods
Section 6-3
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.
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.
3.
The data set in words n+8 and n+9 by PC QWRITE is used only as monitor
data by the CPU Unit. The data that is actually transferred is specified in
an operand of the IORD instruction. This aspect of operation differs from
that of the PC WRITE@ command, which reads data from the operand
specified for it. For the CS1 Series, the range that can be addressed for PC
QWRITE differs from the range for IORD, making it necessary to use dum-
my addresses when executing PC QWRITE if it cannot address the re-
quired words directly. (The CPU Unit will not monitor the words when
dummy addresses are used.) In the above example, the address of the first
word, D07000 cannot be specified for PC QWRITE even though it can be
specified for IORD. Here, a dummy address, like @D,0, can be used for PC
QWRITE.
CPU Unit
ASCII Unit
ASCII
Busy Flag
No . of read words
(BCD)
Unit No.
128 words max.
Control code
DM 0300 as
first word
1. IORD Request Flag (trigger)
1. Allocated words in IR area
3 words from
DM 0300
The ASCII Unit on standby until completion of
IORD execution.
Allocated I/O
3 words
2. IORD instruction
Transfer at IORD execution
14
DM 0300
0301
0302
I/O refresh
At the same time
I/O refresh
10514
IORD
#FD00
#0003
DM0300
0003
n+5
@
14
n+8
n+9
n+8
n+9
B (1)
B (2)
B (3)
PC QWRITE "@D , 300, 3, 1H4, 1H4, 1H4";
B (1), B (2), B (3)
0 3 0 0
0 0 0 3
0 3 0 0
0 0 0 3
10500
n + 5 bit 00
(See note 2)
(See note 3)
@
IORD (222)
#FD00
#00030000
D00300
0003 0000
Unit No.
No. of read words
(Hex)
Summary of Contents for C200H-ASC11
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